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.
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.