Camera Placement

Cameras Placement in Video Surveillance System

This article points several practical aspects of positioning cameras of video surveillance system. Camera placement is the key point of any video surveillance system. Any property has several key zones for monitoring such as entry and exit areas, doors, windows and access ways, to mention just a few of them. In the schematic Outdoor Surveillance below, you see an example of positioning two cameras for monitoring the access to the house and also the entrance to the house.

When positioning the cameras, always pay attention for obtaining a record of the most relevant information on intruder such as face, size and eventually other particular features that will further help to its finding. A good suggestion is for using colour cameras instead of black and white cameras. Skin colour, eyes colour and sometimes cloths colours might help a lot in identifying a person. There are situations such as video surveillance of babies, small children, and also in small businesses, when audio recording can be very useful, too. Some comments on main parameters of video surveillance cameras as shown in the Surveillance Camera Positioning schematic can be helpful.

The lens of most video surveillance cameras has 3.6mm focal length and 67 degrees view angle. Typical cameras can see clear images without adjusting the lens, from 2m away from the lens up to infinity. For 3.6mm lens, Camera Distance to Scene table shows horizontal dimension DH and vertical dimension DV of the scene for several values of Distance between the camera and the scene. This table is for evaluation purposes only, to estimate where you should place the cameras. The table helps you also for positioning multiple surveillance cameras. However, for final positioning of each camera, you must use the camera image displayed by the surveillance system monitor.


Sometimes you must do surveillance of a wide scene, such as shown in Multiple Cameras Layout schematic. In this case, the surveillance must cover an area much wider than a single camera can handle. Obviously, you must use multiple cameras with reasonable overlap of their viewing scenes. Avoid gaps between the viewed scenes for having the full coverage of the area under surveillance.


You must be aware to not mount the camera at more than 10m or 30ft from the scene. Most of surveillance cameras such as Foscam FI8910W Pan & Tilt IP/Network Camera have 640×480 pixels (300k pixels over entire image). This pixel count does not provide clear enough pictures for objects located at more than 10m or 30ft away from camera. For objects located up to this distance, the pictures have reasonable clarity, as you can see below in Mounting Wireless Surveillance Camera schematic.


Mount your camera as shown in the diagram above pointing to the door, but avoid targeting a bright background. If the camera targets a bright scene such as a window, as shown below in Camera and Light Sources schematic in the right hand side, is difficult to identify the intruder face. Obviously, this is not the purpose. The best position for the camera is with the window behind, such as shown in the schematic below, on the left hand side. However, the camera must avoid targeting the bright sources.


Surveillance cameras are equipped with infra red LEDs for illuminating the scene appearing in total darkness to the human eye. Video recordings made in total darkness do not not have the same clarity as the scenes recorded in visible light. However, they give a good idea about the human faces, as you see in the Surveillance in Total Darkness schematic below. Ideally, the camera must be positioned at a convenient height, for having a good record of human faces, too. Be aware that very often, the thieves wear either a hood or a baseball cap, for making their face hard to identify.


We hope that this article provided you some useful tips for installing yourself the surveillance cameras at home and also at your small business.

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Video Surveillance – Do It Yourself

Basic Video Surveillance System – Do It Yourself

For multiple reasons, video surveillance systems are increasingly popular for home and small business. At digishop.org, we target these categories. In this article, we bring to your attention several security aspects of this market segment, for minimizing the cost while increasing the efficiency.

We begin by bringing to your attention a typical scenario for a security company chasing a new client:

A sales person comes with a “very good deal”, such as free surveillance system of $1,200 value including installation, if you accept a 3-years monitoring contract with them, for $40.00/month.

Important to mention: the offer is for a typical security system with central unit, three door contacts, one motion sensor and one smoke sensor.

The math is quite simple: you must pay $480/year, or $1,400 over three years. Apparently, this does not look too bad: if you take for granted $1,200 the price of security system as they claim, for $200 extra you have the system installed by a technician in about 40 minutes, or you pay $300/hour installation fee!

Let’s look further on the surveillance job of the security company. Practically they do nothing until appears an alarm signal from the client, when they check if there is a true signal or not. If a true alarm is acknowledged, they try to reach you by phone, to inform you about an intrusion attempt, or about a fire alarm. If they do not find you, they call the Police. If the Police comes on place and there is no sign of intrusion and if this happens the first time, you get only a warning for a false alarm. If the surveillance company calls the Police again after a while and the Police finds again a false alarm, they will charge you this time! You cannot dispute with the security company; they always claim a perfect system, no glitches whatsoever. If you still insist that the surveillance system had a glitch, they will send you a technician to your premises, but his visit is not free. Usually, the field technicians have low expertise and they end up by doing something wrong in your system, which will create you more problems later. Again, you cannot prove the technician’s expertise level. He is certified by the security company to do this job. You are at the total mercy of the security company. You could break the contract, but you will be charged for this, according to the contract terms. This scenario is not hypothetical. It happened to us several times, turning into nightmare the video surveillance, with a lot of money loss.

 

Fortunately, technical progress in multiple domains such as video capture and storage, wireless communications, Internet and cellular telephony to name just a few of them, make property surveillance much more reliable and more affordable than it was until several years ago. The schematic Basic DIY 24/7 Video Monitoring shows how simple and affordable is to do yourself a 24/7 video surveillance system, monitored by yourself.

 


 

The key piece of your video surveillance is Foscam FI8910W Pan & Tilt IP/Network Camera with Two-Way Audio and Night Vision (Black) which is an integrated unit with high quality color video camera and microphone, infra-red – IR LED for illumination in the dark, pan/tilt function for improved exploration, embedded IR-cut filter and video recording system. The unit can be wirelessly connected to a local area network and further to Internet. However, Internet is increasingly popular and most likely you already have local wireless network installed and running in your premises. Up to four such cameras can be connected to the same wireless router. Any computer, tablet and smartphone (iPhone, Android and BlackBerry) can be used to see the images from cameras if you provide their addresses. Foscam camera has an IR-Cut filter for enhanced color picture quality. With this camera, you have two-way audio, 300 degrees pan and 120 degrees tilt, motion detection with email notification and image upload via FTP. With this camera, you can do video and audio remote monitoring from anywhere in the world where is Internet connection.

The Foscam Blue Iris Professional software allows you to define Motion Detection Zones, has H.264 compression recording, e-mail and SMS text messaging alerts. This software supports several IP camera brands including Foscam FI8910W Pan & Tilt IP/Network Camera and Agasio A502W Wireless IP Camera with IR-Cut Off Filter for TRUE COLOR Images.

We recommend Medialink – Wireless N Broadband Router – 150 Mbps – 2.4GHz – 802.11n w/ Internal Antenna for your local area network – LAN, if you do not have already other router. However we keep posted this router on our list of devices for DIY surveillance system.

You must protect your surveillance system against either intentional or involuntary power failure with CyberPower CP1500AVRLCD Intelligent LCD 1500VA 900W with AVR Tower UPS, which can be used also for powering your computer and your wireless router.

We do not include in our list the smartphone, which we suppose you already have. This is more and more a commodity in these days and also in the immediate future. Using a software application such as IP Cam Viewer for Android, IPad, my Droid 2 and 3 phones, you can listen, control and record your camera from anywhere in the world with Internet connection.

With continuously shrinking prices, we cannot provide you the exact amount for each DIY option mentioned below. You make yourself the calculations by going to the provided links.

Let us summarize our recommendations for using DIY remote video monitoring over Internet:
DIY Option A: You need a single Foscam FI8910W camera. You have the wireless router, backup power supply, and the smartphone. Your investment is below $99.99.

DIY Option B: You need four Foscam FI8910W cameras and also Foscam Blue Iris Professional software. You suppose to have the wireless router, backup power supply, and the smartphone. Your investment is below: $450.00.

DIY Option C: Option B , where you must add the backup power supply. Your investment is below $595.00.

Now, you compare DIY Options A, B and C with:

Security company: $1,400.00 for three years, or $467.00/year and hassle. It is up to you to make comments and to decide which way to go.

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Illumination – Position

Illumination in Digital Photography
Positions of Light Source, Object and Camera

A good photo doesn’t need any change. A bad photo will never be good.

This article deals with very basic aspects of illumination position in digital photography only. It targets the amateurs and does not claim at all to exhaust the subject even at this level. Just it brings to the reader’s attention some basic aspects for making good pictures when shooting with digital camera. We hope this article will raise interest for comments within this site and for further reading on Internet and elsewhere.
 

Simply put, assuming that the subject is not a light source such as lamp, there are three main elements in photography: light source, subject and camera.

The light can come from different sources such as: (i)direct sunlight, (ii)cloudy sun, (iii)sunlight reflected by large objects or surfaces; (iv)incandescent bulb; (v)fluorescent lamp; (vi)street illumination, (vii)LED or (viii)speedlite or flash. Throughout this article we prefer to use speedlite instead of flash, to avoid confusion with flash memory. This enumeration of light sources is based on the color of each illumination source category. Everybody knows that sunlight and bulb light have different colors, and of course, the color of the same object is perceived differently in sunlight and at bulb light. It will be a separate article about the color of light sources and its impact on colors of digital pictures.

There are two major aspects related to light in digital photography:
positions of the light source, of the object and of the camera, and
color of the light source.
This article covers only the positions of illumination source, summarized in Position schematics, with samples of portrait pictures.

Take note that this discussion about positions holds true for any color of the light source.


It is important to mention that the light source in all Position examples has small size, such as a bulb. For outdoor shooting, the Sun is a small size white light source with parallel rays. If you look at the Sun through a strong absorption filter, it appears quite small comparing with a person or with size of any landscape.
In most of the situations, the transitions between light and shadow are sharp. A pleasant portrait must have either no shadows, or very smooth shadows, unless the photographer takes advantage of shadows for highlighting some subject features. Just compare any picture in Position examples with the picture shown in Diffused Sunlight example, where the picture was taken outdoor, in slightly cloudy sky.

 


Everybody wants to shoot nice pictures. This is not difficult to do if the photographer pays attention to some common-sense aspects. In sunlight, the pictures are vivid with natural colors. For a good picture, the photographer must look carefully for smooth transitions from light to shadow on the subject. In Diffused Sunlight example, the light from the Sun was scattered by clouds, which became an extended or broad light source, producing smooth shadows on the subject. In the Diffused Sunlight example, you can easily depict the position of the Sun, but the picture is pleasant.

For indoor portraits, the shadow can be controlled better by using extended light sources such as softbox and studio light source. Below you see examples of both soft sources. The softbox make soft transitions between light and shadow on the object. The studio light source makes a light spot with soft boundaries on the object for highlighting a particular area.
 

Be aware of using studio lights: a softbox gives a single smooth shadow per object feature as you can see on the Smooth Shadows examples below; replacing the softbox with multiple studio lights might make multiple smooth shadows of the same feature of the object.
 

The picture at the left hand side was made using multiple softboxes and also several diffuse reflection panels. For the picture at the right hand side, the photographer used several sources with different colors making diffuse illumination at different angles, as it can be depicted easily.

The softbox can be used also for blurring the edges of the shadows, as you see in the Softbox Comparison schematic.

Several light sources and accessories for diffused light illumination are shown below.


Here is an example of subject lighting in studio using softboxes.

By using the speedlite, either with a flash diffuser or with a speedlite softbox you get astonishing soft shadows and a natural integration of the subject into its background.

Back light illumination is often encountered when shooting either indoor, or outdoor. When the subject is back illuminated, its side facing the photo camera is strongly shadowed by itself. Vast majority of digital cameras have an embedded speedlite. The embedded speedlite will illuminate the subject side facing the camera, but will eventually introduce also shadows on subject if its light is not diffused enough. It is a widespread perception, that the speedlite is used only when there is not enough light for reasonable shooting, either indoor or outdoor, usually indicated by camera. This is partially true. Some comments will clarify the issue.
If the photographer wants to do a quick shot, for a reasonable quality picture it is OK to use the speedlite in this way. The picture eventually will have some shadows with sharp transitions, expected and accepted by the photographer.

If the subject is a person or an animal looking straight at the camera during shooting, the eyes could have red spots or red-eye effect removable further by a multitude of means. Many cameras have the option for red eyes reduction. When you activate this option, the digital camera will light up shortly a lamp for preparing the eye for the strong flash light which will be generated shortly after. We suggest the use of the built-in speedlite for subject illumination only when you do not have a better choice.

More interesting is the situation when the photographer wants to shoot a good picture either indoor, or outdoor, using a standalone speedlite. This option is always better. All embedded speedlites illuminate the object straight, eventually producing shadows with sharp edges. There are available flash diffusers for embedded speedlites. For the standalone speedlites, there are available specially built accessories such as flash diffusers and softboxes, as you can see in Speedlite, Softbox and Diffuser schematic above. The speedlite diffuser gives very good diffused light, is easy to handle and to carry on top of the speedlite. For indoor shooting, it is better to direct the speedlite head toward the ceiling, for taking advantage of further light scattering by the ceiling. Do not worry abut underexposure. Good speedlites such as Canon Speedlite 430EX II Flash for Canon Digital SLR Cameras generates plenty of light and have a dialogue with the camera through the hot shoe. The speedlite measures the back reflected light from the object, makes a dialogue with the digital camera and the camera stops the speedlite lamp when the proper illumination is reached. Having attached either a diffuser or a softbox, the speedlite can be eventually aimed to the object; no worries about shadows.
Just look at the example below to see the difference between the back light illuminated pictures shot without speedlite and with speedlite.

Landscapes are illuminated either by sunlight, moonlight and sometimes by streetlights. These three main lighting categories are very different; therefore we make separate comments for each of them.
For landscapes shot in daylight, side lighting is preferable. In the example below, the shadows highlight some elements and give three dimensional aspect of the picture.
Top lighting might emphasize a certain area of the picture. The photographer can use the lighting for sending a message to the viewer.
Front lighting gives a strong perception about depth; the shadows are very long. For this type of shooting, be aware that the direct sunlight may compromise the entire picture, unless you use a
graduated neutral density filter to mitigate strong light.
Back lighting can produce astonishing pictures, too, when balancing properly the strong illuminated areas with some shadows.


Moonlight is very dim; therefore, the shutter speed is slower in nighttime shooting. Quality moonlight shooting requires a tripod, even when using high ISO speed such as ISO6400 and up. We recommend ISO100 sensitivity for revealing picture details and low noise, thus tripod is a must. Image sensor area should be as large as possible to collect as much light as possible, such as in digital SLR cameras Canon EOS Rebel T3i, Nikon D5100 and similar, or in full frame digital SLR cameras, such as Canon EOS 5D Mark III, Nikon D800 and similar. The lens should have small f/number, and the diaphragm should be as wide as possible. Lens focused at infinity gives the best results, with a large depth of field. If the picture include the Moon, pay attention to its move in the sky. Longer exposure times might elongate the moon, which is not pleasant to see.
Be aware also of the noise (grains) in the image: higher ISO speed means more noise, but ISO100 or lower gives the best results. Shutter release is also very important: triggering the shutter should not move at all the camera.
Shooting streets in the night requires attention to the light from closer lamps, which may affect the shutter speed. As a rule of thumb for any nighttime shooting, take several shots of the same scene with different shutter speeds and focusing. Do not rely totally on the camera auto focus in this case; try manual focus, too. Later you will select the best picture.
Below you have below several examples of beautiful night pictures.

Obtaining good pictures in different illumination conditions is definitely related to photographer skills, which requires passion and experience.
 

We hope that this article will be helpful for improving the skills of people working in digital photography and also will trigger attention on other light related aspects in digital photography.

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About Digital Cameras

About Digital Cameras

Rev. 1

 

Digital photography and video are increasingly popular. The user has more satisfaction and motivation when he or she gets better pictures and videos. We believe that the best way to improve users’ skill is through better understanding of how digital camera works. This article reveals some basic aspects of digital cameras and has suggestions how to use them better. The references about the digital cameras are abundant containing also schematics and various graphs. Anybody can go to Internet and make a search on digital cameras using various search engines. The outcome will be several hundred thousands if not millions of results covering a multitude of direct and related aspects.

This article summarizes the main functions and features of digital cameras, either point-and-shoot – PS, or single lens reflex – SLR. We do not claim complete coverage of the subject. We only highlight key features of digital cameras. It will be a great reward for us if this article can trigger further investigations for those interested to find more information. The reader is strongly encouraged to post comments in this site about this article and also to tell us what particular topics we should comment in the future. Thank you in advance for your help.

 

Digital PS is the modern version of popular viewfinder cameras for films. In digital PS, the lens permanently attached to camera makes the image of the scene on the image sensor built either in CCD technology, or in CMOS technology. Some recent PS camera models such as Canon PowerShot A1300 16.0MP Digital Camera with 5x Digital Image Stabilized Zoom 28mm Wide-Angle Lens and 720p HD Video Recording still have an optical view finder matching the viewing angle of the lens, like its film ancestors. Optical viewfinder is very good when framing the scene in the sunlight. Obviously, this camera has also rear LCD for viewing the scene, as most of digital PS cameras have. We recommend too, this camera to our readers.



Digital Cameras Schematic shows on the right hand side the main elements of typical digital PS cameras. Vast majority of the digital PS cameras, such as Canon PowerShot S100 12.1MP Digital Camera with 5x Wide-Angle Optical Image Stabilized Zoom use only rear LCD for displaying the scene aimed by the lens, at the expense of battery drain. We recommend also this camera, which is pocket-friendly and has the most advanced DIGIC 5 Image Processor. Keep in mind that there are always problems watching the picture on rear LCD in bright ambient light.

Do not forget: rear LCD drains significant power from the battery in any digital camera. For preserving battery life, it is better to turn ON the rear LCD only when you need it. All digital cameras keep ON rear LCD for a limited time selected by the user. We suggest to keep LCD active for 1s.

AUTO Shooting mode gives reasonable quality pictures for most situations. This article summarizes some aspects to consider when shooting to get consistently good quality pictures.

All digital PS cameras have optical zoom lens, but there is also electronic zoom. For good quality picture, our suggestion is for using mostly the optical zoom. When enlarging the image beyond the boundary of the optical zoom, the camera goes into the electronic zoom mode, which may blur the image significantly if enlarging too much. Higher electronic zoom gives more blur. When shopping for a digital PS, look at the minimum focal length and also at the optical zoom factor. Lenses with short focal length have wide viewing angle and vice-versa. Be aware that short focal length may distort the image toward its sides. Optical zoom inherently decreases the picture sharpness toward longer focal length, but the picture has less distortions toward the sides. There are no ways to change this: it is a matter of physics.

When shooting, press the shutter button half way gently and wait one or two seconds to allow the lens to focus the image and also to allow the camera to set properly the ISO_speed, the exposure f/number and shutter speed. You feel half-way position of the shutter as slight resistance at your finger. When you shoot static scenes, several half-way trials give even better ISO_speed, f/number and exposure. Keep in mind that image focusing requires mechanical movement of some elements of the lens; therefore, it requires some time to settle. Do not push the shutter button too fast; you might get blurred pictures. Eventually, the camera “tells” you “when” to press further the shutter button. Check your camera manual for details.

For shutter speed slower than 1/60, we recommend using a stable tripod and camera timer for delayed shooting. In this way, good quality pictures is almost guaranteed. Very few people have “stable” hands for not moving the camera during exposure times longer than 1/60.

In Manual mode, set sensitivity at ISO100, or ISO200 in bright light. For dim light such as candlelight, select ISO3200, ISO6400 or higher, if the camera allows this. There is very little noise in the image when shooting with ISO100. In dim light, you must increase ISO_speed to be able to shoot, but do not be surprised to see speckles or noise in the image. Currently available cameras have some noise at high ISO_speed beyond ISO1600, which is normal. However, camera manufacturers are continuously striving to reduce this noise.

We suggest to select a reasonable picture size of 3072x2040pixels or 2400x1600pixels, or medium-size option. This gives good picture quality on 1900x1024pixels computer screen and also on 4x6inches paper. Digital SLRs offer more choices for picture size, better sensitivity and less speckles when shooting in low light.

If the picture is clear, do not be deceived if it is a little bit either darker or lighter. Anybody can fix this easily by computer, using one of the image viewing applications built in the modern operating systems, either Windows or MAC OS. Rear camera LCD gives you a rough idea about picture quality. For more information on picture, look at its histogram. In Exposure Cases schematic, top row shows a correct exposed picture and its histogram with its maximum roughly in mid tonal range.


Portability and good image quality made today’s digital PS increasingly popular among the amateurs and professionals alike. The continuing progress in electronic technology made digital PS better at affordable prices, with increasingly better image quality.

We recommend several cameras from the Top 100 Best Sellers in digital PS:


Compact System Cameras released recently on the market by several companies such as Nikon, Olympus and Sony are digital PS cameras with lens-changing capabilities. We recommend Nikon 1 V1 10.1MP HD Digital Camera System with 10-30mm VR 1 NIKKOR Lens.

We recommend several cameras from the Top 100 Best Sellers in Compact System cameras:



 

Digital SLR camera as you see in the left hand side of Digital Cameras Schematic, is a modern version of the film SLR camera. A reflex mirror and a pentaprism directs the image from the lens toward the viewfinder. Digital SLR Cutaway schematic gives you 3D perspective of digital SLR camera. Digital SLR camera has two main advantages over digital PS camera: (i) the lens can be changed and (ii) you always see in the viewfinder the image made by the lens regardless of the lens type.

You see below Canon EOS Rebel T3i 18MP CMOS Digital SLR Camera and DIGIC 4 Imaging with EF-S 18-55mm f/3.5-5.6 IS Lens, one of the most popular digital SLR cameras on the market. We also recommend this camera to our visitors.

A digital SLR camera schematic is shown in Digital Cameras Schematic at left hand side and also in Digital SLR Cutaway schematic. In the pointing position, the reflex mirror directs the image upwards to a pentaprism and further to the viewfinder. A smaller secondary mirror, solidly attached to the reflex mirror and behind it, reflects the rays going through the main mirror toward the auto focus sensor located on the bottom side of the camera. Before pressing the shutter button, the operator defines the shooting area by looking through the viewfinder. When the operator presses the shutter button half way, the camera microcontroller adjusts the lens for the best sharpness using signals from auto focus sensor. Digital SLR allows the operator to focus the image either in center or off center in one of the focusing points selected by photographer. The number of image focusing points depend on camera manufacturer. Read carefully your camera manual for details. The same microcontroller adjusts also f/number and eventually the shutter speed for the best exposure for selected ISO_number.

Shutter speed is computed by the microcontroller using the information from the light metering system measuring the luminous flux across the image in up to 252 points. Pressing the shutter button further for shooting, the main mirror flips upwards for covering the pentaprism, thus preventing the ambient light from outside the camera to penetrate into the mirror box area. Now, the light from the lens hits the image sensor and the microcontroller opens the shutter during the shutter speed time. The computation is based on selected ISO_number and other shooting options for obtaining the best light exposure of the image sensor, according to camera firmware. For selecting ISO_speed, follow the same hints as mentioned in digital PS. Digital SLRs have more choices for ISO_speed selection either in bright light, or in dim light. Select ISO100 or less in bright light. For dim light such as from candle, you can select ISO6400 or more, with some loss in image details. If you shoot a static scene in dim light, use a tripod and select ISO100 for preserving image details and for minimum noise. The pictures taken in bright light are practically free of speckles or noise. Camera manufacturers are constantly striving to reduce image noise, which is not an easy task at all.

For shutter speed longer than 1/60, we recommend to use a stable tripod for obtaining consistently good quality pictures. Very few people have “stable” hands to not move the camera during longer exposure times. Make sure that you do not move the camera when you press the shutter button, even if the camera is locked on tripod.

We strongly suggest you to use also a tripod when you you use telephoto lenses with focal length longer than 85mm, even in bright light and when the exposure time is as short as 1/250. The natural move of the hands is heavily amplified by the lens and can blur the image.

Digital Cameras Block Diagram shows the main elements of digital cameras and the functional links between them. The image sensor is a two-dimensional pattern of photosensitive elements or pixels for converting the image in electrical signal. Each pixel is converting the image across its area. More pixels across the image reveal more details of the image. An image sensor with a special color filter on top of it is used for color images. Today, all digital cameras have color image sensors containing between 6M pixels such as Nikon 1J1 and 36.3M pixels such as Nikon D800. The pixel count is very important, but is not the only parameter defining the image quality. Noise level of the image sensor and the Imaging Core have also important contribution to the quality of image conversion.

The Imaging Core process the signal from the image sensor. For clarity purposes, in Digital Cameras Block Diagram we show only Digital Image Processor and the Microcontroller as main components of the Imaging Core. In reality, the imaging core is very complex. Every digital camera manufacturer has its own Imaging Core, such as DIGIC of Canon and Expeed of Nikon. Briefly, the Imaging Core makes image processing, video processing and camera control. Image and video processing are strongly related to the characteristics of the image sensor. The Microcontroller performs multiple tasks, such as reading ISO_number, exposure time and aperture eventually provided by the operator through the user buttons. In automatic mode, the Microcontroller sets all exposure parameters. It performs also the best focus on the image sensor, triggers the flash unit, opens the shutter, saves the picture to the flash card and sends the picture to rear LCD.

Most of SLR cameras have also manual focus option. For best picture quality, we strongly suggest to use by default auto focus, which gives by far sharper images, works faster and gives more reliable results than manual focus. There are also rare situations, such as shooting through chain-link fence, when auto focus will will focus on fence, which is closer to the camera than the targeted subject.

We recommend several Digital SLR cameras from the Top 100 Best Sellers in Digital SLR cameras:


There are several types of flash memory cards for storing pictures of digital cameras, such as secure digital (SD, SDHC, SDXC), memory stick and Multi Media Card (MMC). Always you need one to three spare flash memory cards for your camera. Three elements are important for flash memory cards: (i) mechanical compatibility, (ii) capacity expressed in GB, and (iii) speed. With so many flash card options available on the market, the best advice is to look at the camera manual to see the suggested flash memory cards for your camera. We recommend to choose the largest capacity supported by your camera, and fast enough to accommodate the camera transfer rate. Below are our recommended flash memory cards. For more options, follow the links.


Flash card management is totally at user’s choice. The user can select the picture size saved by the camera, ranging from 720x480pixels, up to 6144x4912pixels. Obviously, larger image size gives more details, but less pictures can be stored on the flash memory card. It is always a tradeoff between the picture details and the number of stored pictures on the flash memory card. This tradeoff is totally the operator’s choice. We suggest a reasonable image size of 3072x2040pixels or 2400x1600pixels, giving good picture quality on 1900x1024pixels computer screen and also on 4x6inches paper. Typically, the digital cameras store the picture in compressed .jpg format, widely accepted by most computers and Internet applications. All digital SLRs can store pictures in RAW image format, to avoid compression artifacts associated with .jpg compression. Be sure that your camera was set to store the pictures in .jpg format, for efficient use of your flash memory card, for easy transfer to your computer and for easy reading using the image readers available in major operating systems of computers and smartphones. Picture files in RAW format are used at professional level. They are very big, take a lot of space on your flash card, and need camera manufacturer software for transferring them to your computer.

All digital cameras are provided with USB connection for transferring the pictures either to a computer, or to an iPad. Be aware that USB transfer from camera consumes a significant amount of power from camera battery. Our suggestion is for using a flash memory card reader connected to a computer, which does not affect at all camera battery life.

When the scene is not sufficiently lit for taking a good picture, use either the built-in flash unit, or external flash unit.

By default, the digital cameras keep ON the rear LCD for a limited time, for preserving the battery life. The ON time is set to default value in factory before shipping the camera, but it can be changed anytime by the user within large limits. We suggest 1s display time.

Many digital photo cameras have output for video signal, which allows you to see the pictures on TV. Be aware that the available TV signal at the camera output must match the TV standards of your geographic region, such as NTSC for North-America, PAL and SECAM for Europe.

The high speed connection according to IEEE1394 standard is optional for some digital photo cameras, but is always present in camcorders.

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Advanced Lenses

Advanced Lenses For Digital Cameras

The progress of digital SLR cameras is credited mainly to the trinity: lens, image sensor and digital image processor. At digishop.org, you have more than 1,350 digital SLR cameras to choose from. Selection of digital SLR camera is subject of many criteria, technical and personal. We do not touch the personal criteria; they are out of any discussion. In this article we use our professional expertise to bring into discussion several features of advanced lenses such as Image Stabilization – IS and Tilt Shift – TS. By explaining how these features work, we hope to help users to shoot better pictures. We strongly recommend you to consider this article as an incentive for reading more on the topics below and also for discussions and practicing on this subject. We review first some parameters frequently advertised for digital SLR cameras and also related to these advanced lenses.

 

Number of pixels such as 18MP and 22.3MP is frequently used feature for advertising digital SLR cameras. We show below the connection between the number of pixels and digital SLR camera lenses. Each digital SLR camera manufacturer has lenses compatible with its cameras. Lens compatibility covers not only the mount, but also optical parameters and electrical compatibility with camera body, including the operation of lens features. Obviously, there is a very strong functional link between digital SLR camera and the lens attached to it. If you do not use the lens to the recommended camera model, some features of the lens might not work, even if the lens and digital SLR come from the same manufacturer.

 

Camera format such as APS-C and Full Frame refers to the sensor size, as you see in the Cropped Images schematic for three very popular Canon image sensors, which shows also sensors dimensions.

Full Frame sensor size has the advantage of larger field of view of lenses designed for this format. The drawback is large size of camera body and of lenses designed for Full Frame format. APS-C sensors have some advantages for telephoto. Digital SLR cameras with APS-C sensor are more compact and lighter than Full Frame SLR cameras. Also the lenses designed for APS-C sensors are smaller and lighter than the lenses deigned for Full Frame sensor. It is easy to understand that optimization for a particular image sensor covers camera and also the lenses designed for that sensor. You will see below the main aspects below.

 


Some comments on sensor format, number of pixels, pixel area and pixel size for Canon and Nikon brands will clarify several aspects, directly applicable to other brands, too.

 

Canon APS-C sensor size is 22.2mmX14.8mm, or 329sq-mm [square-millimeters] area. For 18MP count such as in Canon EOS Rebel T3i 18MP camera, pixel area is 18.3sq-microns [square-microns], or about 4.3micronsX4.3microns size [1micron = 0.001mm]. Canon EOS 5D Mark III 22.3MP Full Frame camera has Full Frame sensor with 36mmX24mm size, or 864sq-mm, which is 2.63 times larger than APS-C sensor area. With its 22.3MP, pixel area is 38.74sq-microns or about 6.2micronsX6.2microns size, which is 2.11 times larger than the pixel area of APS-C sensor. From these examples, we conclude two aspects:

(i) One pixel of Full Frame sensor is about two times larger than one pixel of APS-C sensor and obviously captures about two times more light than one pixel of APS-C sensor. Therefore, Full Frame sensor is twice more sensitive to light than APS-C sensor, which is good for low-light exposure.

(ii) In all digital cameras, each pixel takes a sample of the image across its area. Entire digital picture is no more than a collection of samples taken by each pixel. Higher pixels per unit area or pixel density gives a sharper image than lower pixel density. In our situations, pixel density of 22.3MP Full Frame sensor is 0.026MP/sq-mm, and of 18MP APS-C sensor is 0.055MP/sq-mm. If the appropriate lens is used for each sensor, the math is quite simple if we consider APS-C sensor as reference: 2.63 times larger area of Full Frame sensor has 2.11 times larger pixel size. There is no significant difference in image sharpness between APS-C cameras and Full Frame cameras. Full Frame cameras have larger Field Of View or FOV, as you see in DX and FX Cameras with Lenses. We notice that DX cameras give slightly less sharp pictures, have lower light sensitivity and smaller size and weight than FX cameras. You can overcome light sensitivity issue by using a tripod, which however must be used for good quality picture in low light at ISO100 speed. Large FOV is the main advantage of Full Frame digital SLR, not considering other features not encountered in DX cameras.

(iii) Several lenses such as Canon EF-S 55-250mm f/4.0-5.6 IS II Telephoto Zoom Lens for Canon Digital SLR Cameras, are optimized for image projection on entire surface of APS-C sensor, having crop factor close to one. If you use Canon EF 75-300mm f/4-5.6 III Telephoto Zoom Lens for Canon SLR Cameras optimized for Full Frame sensor on camera with APS-C sensor, the image will be cropped with 1.6 factor in its central part, as you see in the Cropped Images schematic. However, APS-C cropped picture will reveal more details of the image than the picture shot with the same Full Frame lens mounted on Full Frame camera. In the schematic below, you can compare the blurred picture with sharp picture. You should be aware that blur was exaggerated on purpose, for understanding the difference. Spatial resolution is the professional term used for image sharpness: high spatial resolution reveals more details than low spatial resolution.

 


Nikon DX sensor size is 23.6mmX15.8mm, or 372.88sq-mm area. For its 24.2MP count such as in Nikon D3200 24.2MP CMOS Digital SLR, pixel area is 15.4sq-microns, and pixels density is 0.065MP/sq-mm. With Nikon 55-200mm f/4-5.6G ED IF AF-S DX VR Nikkor Zoom Lens optimized for DX sensor, crop factor does not limit the picture size. The FX sensor of Nikon D800E 36.3MP CMOS FX-Format Digital SLR Camera has 36mmX23.9mm size, with total area of 860.4sq-mm and pixels density of 0.042MP/sq-mm. Using DX sensor as reference, FX sensor pixel area is 1.5 times larger than the area of DX pixel with total area 2.3 larger than of DX total area. Looking at these numbers, at FX sensor we see 1.5 decrease in picture sharpness, but 2.3 time increase in light sensitivity. Not counting additional features of FX cameras, DX cameras give better picture sharpness with less light sensitivity than FX cameras. Using ISO100 and a tripod when shooting, light sensitivity can be compensated by longer exposure. With Nikon 35mm f/1.4G AF-S FX SWM Nikkor Lens for DSLR Cameras optimized for FX sensor, Nikon D800E DSLR will give theoretically finer details than Canon EOS 5D Mark III 22.3MP Full Frame camera with Full Frame Canon EF 75-300mm f/4-5.6 III Telephoto Zoom Lens. The picture file released by digital camera is subject to very complicate computations made by its digital image processor, which can affect details of the final picture.

DX and FX Cameras with Lenses schematic shows the fields of view of each FX and DX Nikon cameras equipped with their optimized lenses. DX configuration has a narrower field of view or FOV than FX configuration. Nikon D3200 24.2MP DX CMOS Digital SLR with FX optimized lens will crop the central part of the image with 1.5 crop factor, showing slightly finer details than the image of the same object taken with DX optimized lens.

 



Modulation Transfer Function or MTF is a measure of optical quality of a lens. Its graphs show the contrast and resolution of the lens from center toward its edge against a “perfect” lens that transmits 100% of the light and makes the image with infinitely small details. Of course, the perfect lens does not exist; it is just a theoretical reference. Any MTF graph plot shows on horizontal axis X, the distance from lens center toward its edge, in millimeters. The vertical axis Y shows the transmission from zero (no transmission) to 1 (100% transmission). MTF plots are traced along two conventional lines or directions named Sagittal and Meridional, for two spatial frequencies defined by two line patterns:

(sf1) Low spatial frequency MTF plots for 10lines/mm (100microns center to center line spacing) for lens contrast feature.

(sf2) High spatial frequency MTF plots for 30lines/mm (33.33microns center to center line spacing) for lens resolution or sharpness.

The schematic below gives better perception for line groups and also for Sagittal and Meridional lines.


For Canon APS-C image sensor with 18MP, there are about 23pixels within 100microns (10lines/mm) line spacing and 7.75pixels within 33.33microns (30lines/mm) line spacing. These numbers of pixels sample the image on image sensor above the Nyquist rate required for minimum recovery of the original image from sampled picture. As general rule, more pixels (samples) give sharper image.

 

Below you see two MTF examples for Canon EF-S 55-250mm f/4.0-5.6 IS II Telephoto Zoom Lens for Canon Digital SLR Cameras.


 

How can we read the above MTF diagrams? This is a zoom lens between F=55mm and F=250mm. Accordingly, the diagrams are for both focal distances F=55mm MTF Canon EF-S 55-250mm f/4-5.6 IS II and F=250mm MTF Canon EF-S 55-250mm f/4-5.6 IS II. Canon MTF Charts have specific meanings such as:

(a) Thick lines are for 10lines/mm, and thin lines are for 30 lines/mm.
(b) Black lines are for maximum aperture f/5.6 and blue lines are for f/8.
(c) Solid lines on the graphs are for meridional direction of the image.
(d) Dashed lines in the graphs are for sagital direction of the image.
(e) The difference between sagital and meridional graphs comes from lens astigmatism.

 

Conclusions from the MTF graphs:

F=55mm

(c1) The contrast is almost constant across the entire lens aperture for f/5.6 diaphragm, on both meridional and sagital directions. On sagital direction, for f/8, contrast drops monotonically up to 70% by the lens boundary.

(c2) The image resolution or sharpness has little change across both meridian directions for both f/5.6 and f/8 diaphragms. On sagital direction, sharpness has its maximum value in the central region of the lens up to 3mm radius, then decreases monotonically up to 40% by the lens boundary for both f/5.6 and f/8.0 diaphragms.

F=250mm

(c3) The contrast is almost constant for f/8.0 on meridional direction and has a small drop on sagital direction over more than 10mm radius. It is almost constant across the entire aperture for f/5.6 on meridional directions.

(c4) The sharpness has a drastic decrease for f/5.6 over 10mm radius, on both sagital and meridional directions. For f/8 on meridional direction is a 15% decrease from center to boundary, but for f/5.6 is a steep decrease up to 30% on both meridional and sagital directions. This lens gives a blurred image toward boundaries. Do not worry about this; it is very hard to notice that blur!

 

Lens contrast is linked to its resolution: when resolution decreases, contrast decreases, too; it is physics behind.

 

We show below also MTF plots for Nikon 55-200mm f/4-5.6G ED IF AF-S DX VR Nikkor Zoom lens, equivalent to the previous Canon lens.

 


 

Nikon shows MTF graphs also for minimum (Wide) and maximum (Tele) focal distances, with all notations on them. These plots show an overall lens behavior for Wide F=55mm focal length and for Tele F=200mm focal length.

 

There is no widely accepted standard for lens testing and for producing MTF graphs. Each lens manufacturer has its own procedures. Therefore, it is difficult to compare lenses with apparently similar focal distances and f/number from different manufacturers. However, the lens always works with the image sensor and with digital image controller. Ultimately, all these three elements must be considered together, or in other words, the picture counts.

Conclusions on lens optical quality:

(LQ1) Check to see if lens manufacturer provides MTF graphs. The lens should be made under tight quality control.

(LQ2) Select a lens with flat MTF graphs across maximum possible extent.

(LQ3) Final and the best check: look at the sample pictures made with your selected lens posted in your preferred sites dedicated to pictures.

We recommend several popular lenses. Each link below directs you not only to the lens, but also to many pictures made with that lens.



 

Image stabilization

For each photographer, every type of lens leaves its “touch” on the image. This explains the large variety of available lenses compatible with practically all models of digital SLR camera from the same manufacturer such as Canon, Nikon, Sony, Olympus and Panasonic.

 

There are two types of subjects in photography: static and moving, and also two ways of shooting: handheld and using tripod. In all the above discussions, we assumed shooting static subjects with camera locked on rigid tripod. Very often, professional photographers shoot static subjects with tripod and at low speed such as ISO100 or ISO200 for the best picture sharpness. Assuming a perfect focus in handheld shooting, the camera always moves slightly during the exposure; the only question is how much it moves. If the camera moves within the sharpness limits of the lens, you do not see the movement in the picture. If the camera moves beyond the sharpness limits, the picture appears blurred more or less. The photographers use various approaches to get sharp pictures when shooting with handheld camera:

(sh1) Increase camera sensitivity to ISO200 or more. According to several camera specifications, you can shoot pictures with correct exposure up to ISO6400 or more. Be aware that at high ISO_speed, the picture gets blurred because of image sensor noise. Higher ISO_speed, more noise in the picture.

(sh2) Decrease the exposure time. For shutter speed of 1/125 or less, you get a reasonable sharp picture with handheld shooting. It is expected a blurred image when shutter speed is longer than f/[focal length]. This empirical rule shows that shooting with telephoto lenses are likely to blur the image for handheld shooting, unless the image move is mitigated up to the point where the camera autofocus can work properly.

(sh3) Open more the diaphragm or iris, to get more light on the image sensor. Be aware that the diaphragm number defines the depth of field – DOF of the lens. As an example, f/4 diaphragm has shorter DOF than f/8 diaphragm; therefore you are playing with the depth limits of image sharpness.

 

Image Stabilization (IS) feature mitigates the image shake on image sensor, thus allowing stable image up to four stops slower. This is a tremendous advantage versus the regular lenses without IS, especially when shooting in darker ambient light. Notice that this article is not an advertising for manufacturers of IS lenses. We provide professional expertise for the benefit of photographers by explaining how IS features work. All the examples have references to their respective sources.

The schematic Canon Conventional IS – OFF shows two arbitrary situations encountered in normal operation when using regular lenses for shooting, or when using a lens with disabled IS feature. This schematic shows a simulated shake for better understanding of the real case when using telephoto lenses. You notice the difference in scene positions between the two instances. The scene moves too much and too fast, preventing the camera to focus on the scene.

 


The schematic Camera Shake below explains camera movement during shooting.

 


When shooting either a static or a slow-moving scene, camera shaking in arbitrary way can be decomposed in tilt and shift shakes as shown in Camera Shake schematic above. Any tilt has a horizontal component (yaw) and also a vertical component (pitch) as figured out by the arrow pairs. Accordingly, there is an angular velocity sensor for each tilt component. Angular tilt of the camera lens produces an image shift on the image sensor. Camera processor uses the signals from these two angular velocity sensors for shifting the Image Stabilizer perpendicular on optical axis. Tilt Compensation schematic below shows how conventional IS works. You can see also the look of some Canon IS units.

 



IS operation is simple: when the lens tilts downwards, the image projected by the lens on the image sensor shifts. The Image Stabilizer Unit within the lens shifts its Image Stabilizer Lens perpendicular to the optical axis according to signals provided by both angular velocity sensors. It is obvious that the Image Stabilizer Lens moves simultaneously in two directions within a plane perpendicular on the optical axis. This reduces significantly the image shift on the image sensor up to the equivalent of four stops slower. This classical image stabilization has different brand names. Canon calls it Image Stabilization IS Mode 1 and Nikon calls it Vibration Reduction VR. It is really great help for many situations. Of course, IS or VR feature can be enabled and disabled anytime by the user.It is obvious that there is a time constant associated to this image stabilization.

WARNING: Long focal length is likely to produce blur with classical lens even when shooting at 1/125 or less. Image stabilization does not work if the image shakes too fast. When shooting with IS enabled, be careful to stay within maximum four stops slower than when IS is disabled.

The schematics below show two situations of aiming the scene with IS disabled and enabled. It is easy to notice how small is the image shift on image sensor surface with IS enabled.

 



In the above example, notice that Canon IS I works better on the swimmer than on the water waves and drops, which move faster than the swimmer. This example is in good agreement with the initial assumption of shooting either a static or a slow-moving scene mentioned at the beginning of description of IS operation.

 

When panning camera on a moving subject such as shown in Canon Image Stabilization IS-Mode 2 Panning schematic, IS operation may interfere with subject background. Both the subject and the background are moving.
In horizontal panning, the photographer follows the subject horizontally. The subject moves slower than the background, with sudden changes in its positions towards the frame. In this case, IS must compensate only for vertical changes. The background appears blurred.
In vertical panning, IS must compensate only for horizontal changes. Canon calls IS Mode 2, image stabilization on panning.


Schematic below shows Canon EF 70-300mm f/4-5.6 IS USM Lens for Canon EOS SLR Cameras with the operating instructions for selecting IS 1 and IS 2 modes of operation.

 


We recommend below several Canon lenses with IS feature. For the entire range of Canon IS lenses, visit the link Canon Image Stabilization Lenses.

(ISL1) Canon EF-S 55-250mm f/4.0-5.6 IS II Telephoto Zoom Lens for Canon Digital SLR Cameras

(ISL2) Canon EF 75-300mm f/4-5.6 III Telephoto Zoom Lens for Canon SLR Cameras

(ISL3) Canon EF 75-300mm f/4-5.6 III USM Telephoto Zoom Lens for Canon SLR Cameras

(ISL4) CANON EF 75-300 III F4-5.6

(ISL5) Canon EF 70-300mm f/4-5.6 IS USM Lens for Canon EOS SLR Cameras

(ISL6) Canon EF 28-135mm f/3.5-5.6 IS USM Standard Zoom Lens for Canon SLR Cameras

(ISL7) Canon EF 24-105mm f/4 L IS USM Lens for Canon EOS SLR Cameras.

 

Several Canon lenses have IS Mode 3 feature which stabilizes image only when the shutter is fully pressed. IS Mode 3 is recommended for fast acting scenes, such as sport subjects. IS Mode 3 is an extension of IS Mode 2, which stabilizes the image on direction perpendicular to panning.

We recommend several Canon lenses with IS Mode 3, such as:

(ISL8) Canon EF 300mm f/2.8L IS USM II Super Telephoto Lens for Canon EOS SLR Cameras

(ISL9) Canon EF 400mm f/2.8L IS USM II Super Telephoto Lens for Canon EOS SLR Cameras

(ISL10) Canon EF 500mm f/4L IS II USM Lens

(ISL11) Canon EF 600mm f/4L IS II USM Lens.

 

Hybrid Image Stabilization stabilizes for both tilt shake and shift shake. This feature is encountered at Canon EF 100mm f/2.8L IS USM Macro Lens for Canon Digital SLR Cameras. The schematic below shows the stabilization features of the lens and a picture of it.


Dynamic IS feature added on top of IS feature adds image sharpness when the subject moves either toward camera or in opposite direction, shown as Axial Shake in Camera Shake schematic. Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens has Dynamic IS feature, very useful for video shooting. Below you have an image of this lens.




 

Nikon Vibration Reduction – VR technology uses the same principle as Canon Image Stabilization – IS technology, explained in Tilt Compensation Schematic. As you see in this schematic, Vibration Reduction Units and Image Stabilization Units look similar, but of course there are different, built according to each manufacturer’s system design: digital camera and lenses for them. VR II option operates faster than VR option.

For panning, VR detects camera movement and automatically suppresses the blur-correction function. If the camera shakes horizontally, VR reduces blur in the vertical direction. With this function, the panning effect is maximized. Panning Detection is effective regardless of the camera’s orientation or direction of motion, either horizontal or vertical.

A schematic of Nikon 18-200mm f/3.5-5.6G AF-S ED VR II Nikkor Telephoto Zoom Lens for Nikon DX-Format Digital SLR Cameras and a schematic of Vibration Reduction features of VR and VR II models are shown below.

 


We recommend below several popular models of Nikon lenses with VR features, from the top list of our Nikon lenses collection. For our entire VR collection, visit Nikon VR Lenses for Nikon digital SLR cameras.

(VR1) Nikon 55-200mm f/4-5.6G ED IF AF-S DX VR [Vibration Reduction] Nikkor Zoom Lens

(VR2) Nikon 18-200mm f/3.5-5.6G AF-S ED VR II Nikkor Telephoto Zoom Lens for Nikon DX-Format Digital SLR Cameras

(VR3) Nikon 55-300mm f/4.5-5.6G ED VR AF-S DX Nikkor Zoom Lens for Nikon Digital SLR

(VR4) Nikon 70-300mm f/4.5-5.6G ED IF AF-S VR Nikkor Zoom Lens for Nikon Digital SLR Cameras

(VR5) Nikon 18-200mm f/3.5-5.6 G ED-IF AF-S VR DX Zoom Nikkor Lens

(VR6) Nikon 18-200mm f/3.5-5.6G AF-S ED VR II Nikkor Telephoto Zoom Lens for Nikon DX-Format Digital SLR Cameras

You see sample images with Nikon VR disabled (OFF) and enabled (ON).



 

Tilt Shift – TS Lenses

In the schematic Perspective Correction with TS Lens the same building was shot from the same position with a regular wide angle lens (left) and with TS lens (right). The picture on the left has the inherent geometric distortions of the wide angle lens when shooting relatively close to subject. Skilled photographers use sometimes these distortions for producing special effects.


When you want the building to appear straight all the way up, the use of Tilt Shift – TS lens is required. The operation of TS lens is based on Scheimpflug principle shown in the schematic Tilt For Focus on Oblique Subjects below.


Scheimpflug discovered more than 100 years ago that you can get sharp images with very large Depth Of Field for subjects making an acute angle with the image senor (in our case), if you tilt the lens in such a way that the subject plane, the lens plane and the image sensor plane all meet along the same Hinge Line, followed by a lens shift to make the image on the sensor. The schematic Tilt For Focus on Oblique Subjects shows the Hinge Point, which is the intersection between the Hinge Line and the plane of schematic.

Practically, with TS lenses you make perspective corrections in two steps:
First, tilt the lens for focusing on subject.
Next, shift the lens until you get the best perspective correction, as in the diagram below.
If necessary, make another iteration until you get the best image, then shoot.


Electro-Magnetic Diaphragm – EMD module of canon works in tandem with electronic lens system for providing accurate control of light flux on the image sensor and almost circular aperture shape. The schematic Canon EMD below shows simulated extreme positions of diaphragm.


Below you see a picture of Canon TS-E 17mm f/4L UD Aspherical Ultra Wide Tilt-Shift Lens for Canon Digital SLR Cameras.


You can have access to our entire Canon TS lenses collection by visiting the link Canon Tilt Shift Lenses. We recommend below from the most popular models:

(CTSL 1) Canon TS-E 24mm f/3.5L II Ultra Wide Tilt-Shift Lens for Canon Digital SLR Cameras

(CTSL 2) Canon TS-E 17mm f/4L UD Aspherical Ultra Wide Tilt-Shift Lens for Canon Digital SLR Cameras

(CTSL 3) Canon TS-E 24mm f/3.5L Tilt Shift Lens for Canon SLR Cameras.

Follow the link Nikon Tilt Shift Lenses for our entire Nikon TS Lenses collection. We recommend several models below:

(NTSL 1) Nikon 45mm f/2.8 Perspective Control-E Nikkor Aspherical Manual Focus Lens – Grey Market

(NTSL 2) Nikon 24mm f/3.5D ED PC-E Nikkor Ultra-Wide Angle Lens for Nikon DSLR Cameras

(NTSL 3) Nikon 85mm f/2.8D PC-E Micro Nikkor Lens.

We suggest also Arsat brand of TS lenses for Nikon, Canon, Sony and Minolta cameras.

Fisheye and Fisheye Zoom Lenses

These lenses create special effects even during shooting. Of course, the enthusiast is limited only by imagination for post processing using photo editors available in our site in Digital Lab department.

You see below Canon EF 8-15mm f/4L Fisheye USM Ultra-Wide Zoom Lens for Canon EOS SLR Cameras and two pictures taken with this zoom lens.


We recommend also the popular Canon EF 15mm f/2.8 Fisheye Lens for Canon SLR Cameras with fixed focal length. The schematic below has the picture of the lens and also two sample images made with it.


We recommend Rokinon FE8M-N 8mm F3.5 Fisheye Lens for Nikon (Black), a very popular lens. See below the lens picture and two sample images taken with this lens.


Conclusions

We highlighted some advanced aspects of lenses for digital SLR such as MTF, image stabilization, TS and fisheye. For better understanding of lens features, we explained them in connection to several parameters of image sensors. Our idea is to help the photographers to take a better decision when buying lenses with advanced features and also for using these lenses at their full potential by knowing the basics behind their operation. Obviously, our purpose was not to exhaust the subject, but to reveal several important aspects. We hope that this article will help the photographers for better use of presented lenses and also will stimulate their interest to go in further details.

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Recommended Lenses

Recommended Lenses

of this department have high rated products, usually above four-stars, from more than 100 users. For reference, we post also sample pictures made with the recommended lens attached to a digital SLR with image sensor size of 18MP or higher, for revealing the finest details of the image.

 
 
Canon EF-S 55-250mm f/4.0-5.6 IS II Telephoto Zoom Lens for Canon Digital SLR Cameras


Lens Specifications:
Focal Length and Maximum Aperture: 55-250mm; F/4-5.6; Telephoto Zoom lens
Optical System: 12 elements in 10 groups, including one UD-glass element
Diagonal Angle of View: 27-degrees to 6-degrees (with APS-C image sensors)
Focus Adjustment: DC Motor, Gear-driven
Closest Focusing Distance: 3.6 Ft./1.1m
Filter Size: 58mm

 

Sample Pictures



The diagrams below show the position of IS element and also the position of UD element that mitigates the chromatic dispersion of entire lens. The Canon IS diagram shows one example of Image Stabilization unit used in some Canon lenses.


 

Canon EF 70-300mm f/4-5.6 IS USM Lens for Canon EOS SLR Cameras


Lens Specifications:
Focal Length and Maximum Aperture: 70-300mm / 4-5.6, Telephoto Zoom
3-stop Image Stabilizer
Electro-Magnetic Diaphragm (EMD) with defocused background
Optical System: 15 elements in 10 groups
Super Spectra lens coating and lens shaping for anti flare and ghost removal
Gyro sensors for detection of unwanted vibrations
Focus Adjustment: Ultra Sonic Motor (USM)
Closest Focusing Distance: 4.9 ft./1.5m
Length: 5.6 inches; Weight 22.2 ounces; 1-year warranty
 

The Canon Shake compensation diagram shows in more detail the position of Image Stabilization unit used for shake mitigation in some Canon lenses.

 

Sample Pictures




 

Canon EF 75-300mm f/4-5.6 III Telephoto Zoom Lens for Canon SLR Cameras


Lens Specifications:
Focal Length and Maximum Aperture: 75-300mm / 4-5.6, Telephoto Zoom
3-stop Image Stabilizer
Electro-Magnetic Diaphragm (EMD)
Super Spectra lens coating and lens shaping for anti flare and ghosting
Optical System: 13 elements in 9 groups
Diagonal angle of view: 32-degrees (at 11 feet) to 8-degrees (at 15 feet)
Focus Adjustment: Ultra Sonic Motor (USM)
Closest Focusing Distance: 4.99 ft./1.5m
Filter size: 58mm
Gyro sensors for detection of unwanted vibrations
Length: 5.6 inches; Weight 22.2 ounces; 1-year warranty

 

Sample Pictures



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Posted in Recommended lenses

Camera Lenses

Digital Camera Lenses

Lens makes the image of the object on the image sensor. The photographer’s skill goes through the lens. Lens manufacturers work very hard to release new lens models with lower geometric distortions, better image clarity at continuously decreasing price. Its importance is obvious. This article highlights some basic aspects of camera lenses for better use of any lens and recommends you the best lenses for major subject categories.

 

Crop factor is the number showing the ratio between the diagonal of 35mm film format and the diagonal of a particular image sensor. Full-frame image sensor collects the entire image of the lens designed for 35mm film camera; therefore the sensor gets the entire light collected by the lens, as you see in Cropped Images schematic. With a full frame camera, you expect the best outcome in angle of view and also in picture details. For full-frame sensor, camera sensitivity is limited only by the image sensor’s technology for a given lens. We recommend the best wide angle lenses for digital SLR:


APS-C sensor has 25.1×16.7mm with aspect ratio 3:2 and crop factor 1.6. It is encountered in Canon EOS Rebel T3i,18MP, CMOS APS-C Sensor, DIGIC 4 Image Processor and also in other very successful digital SLR cameras. With its 18MP pixel count at relatively small size, the sensor renders very well fine details of the image, as you can see in the sample image below.

 


The link between the lens for digital SLR and the image sensor is obvious. Lenses for digital SLR must fit the entire line of cameras, from the lowest cost up to high-end units of the same manufacturer. Major differences between different camera grades come from the combination image sensor and digital image controller. Smaller-size image sensor at lower cost crops from lens image the central part with inherent loss in sensitivity or in ISO_number. Full-frame image sensor has the same angle of view like 35mm film camera captures the entire image from the lens. APS-H is an older version of image sensor with crop factor 1.3. It is encountered in products such as Canon EOS 1D Mark IV, 16.1MP CMOS Digital SLR Camera. However, you should keep in mind that the image sensor might see less from the image than you see through the viewfinder. Lower the crop factor, less image area covers the image sensor. The picture always shows what the image sensor has on its surface. We recommend the best lenses for APS-C sensors:




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Focal Length defines the size of the viewing angle of the lens. Smaller focal length lenses have larger viewing angle and gets less details of the scene. Longer focal length lenses have smaller viewing angle, but you get more details from the scene. The schematic Focal Length Comparison above give you an idea about the pictures of the same subject shot with two lenses with very large difference between their viewing angle. The available focal length of today’s lenses cover a broad range, from 10mm to 800mm. Lenses can have either fixed focal length or can have variable focal length or “zoom” within a certain range to expand part of the scene. Generally, fixed focal length lenses give pictures with more details and less distortions than the zoom lenses. With a zoom lens, you can select quickly just part of the scene without changing the lens or the the distance from camera and the scene. With a zoom lens, you just increase the focal length of the lens until you reach the desired detail, of course limited by maximum focal length. This can be very useful in many situations. Sometimes, you cannot go close to the scene as you wish. However, the “default” lens of the camera is subject to the operator’s choice.

 


Aperture marked on the lens as f/# selects the depth of field and also controls the light flux through the lens. Smaller f/# gives a clear image within a small depth of field, providing better image resolution or sharpness within the depth of field. Larger f/# gives larger depth of field, but with some loss in details. Diffraction is the physics behind this.


 


Exposure and Image Focusing jobs are preferable to be transferred to digital cameras. The digital SLR cameras have very sophisticated methods to measure the light. The diagram Light Metering Zones shows the light metering zones used by major digital SLR camera manufacturers such as Nikon and Canon. For most cases, auto focus does a better job than any operator unless special effects are targeted through manual settings.

Image sharpness as explained above assumes neither camera shake, nor subject shake when shooting, picture size selection on camera as medium or large, and no zooming when viewing the picture on 1920x1000pixels LCD monitor. Briefly, blur in digital images comes either from shooting conditions, or from electronic conditions such as storing and viewing. Some comments on image blur from shooting conditions can be helpful.

 


In the schematic Blurred Image Cases, the top row shows on the left hand side an image improperly focused on far field, behind the subject, sitting in the front. The correct picture is beside it. The middle row shows on the left hand side the situation when the camera moves during shooting: everything is blurred. Beside it is the correct picture. In the picture on the bottom row, left hand side, the subject is moving during shooting: it appears blurred, compared with the clear surrounding. In the picture beside it, the subject does not move during shooting and the picture appears clear everywhere.

Hint: Improve your photographic skills by analyzing your bad pictures. The examples above refers only to blurred pictures, but can be other situations such as improper lighting, exposure, framing, to name just a few, which will be discussed later.

 


Image Stabilization is a very interesting lens feature, almost standard encountered at digital camcorders. Image stabilization provides sharp image when the camera shakes for different reasons. Read more about image stabilization in Advanced Lenses article.

We recommend several Image Stabilization lenses from Canon. For more lenses with Image Stabilization feature, follow the link.



Below we show sample images shot with recommended Canon Image Stabilization lenses.


 

We recommend several Vibration Reduction lenses from Nikon. For more lenses with Vibration Reduction feature, follow the link.



Below we show sample images shot with recommended Nikon Vibration Reduction lenses.



 

Camera lenses is a very competitive market. Certainly, lens price is strongly linked to its features.

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