There are many ways that lighting effects photography, and for this discussion we will assess only the most controllable and significant ways that lighting and photography work together. We are going to look at how a modern digital camera will interpret light as well as the differences between the ways that low-cost point and shoot cameras and their high-end DSLR cousins each do this. We will also consider the “temperature” of the light in a photograph and why the “sweet light” hours produce some superior effects. Lastly, we will look a bit deeper into color and light temperatures and how the white balance can fix the appearance of any photograph that is showing a tendency toward an inaccurate cast or hue.
Let’s begin with understanding how the camera interprets light. First of all the modern digital camera is going to have a sensor that is a substitute for the film that was once used to record the image. This sensor can be extremely small (as is the case with a point and shoot model) or it can be somewhat substantial, but regardless of the size of this sensor, the camera is going to have to be told how much light to expose the sensor too, and for how long.
Clearly, we are referring to what are known as “exposure settings” and these are usually derived from a few photographic needs and instrument readings. Exposure includes shutter speed, aperture, and ISO, and these settings are dictated by the environment, ambient light, and desires of the photographer. There is an endless assortment of settings due to the wide array of photographic scenarios, but there are some general patterns that emerge when specific results are needed or desired. For instance, a photographer is going to understand that a low aperture setting will allow lots of light into the camera, and this is something that can be used to compensate when lighting is not flexible or readily available.
How does a photographer know what exposure settings to use for their particular image? This is where it is necessary to understand exactly how the camera interprets the light. Firstly, all cameras (regardless of their price tags) have a built-in light meter that is capable only of measuring reflected light. If you consider any scene or setting you will know that there is a light source somewhere within it, this is called incident light. This incidental light strikes the surface of the photographic subject in many ways and in many places, and then this is all reflected back towards the camera. The onboard meter measures this light and tells the photographer the exposure settings needed.
Meters in digital cameras can be extremely basic, such as the center-weighted versions, or they can be much more specific such as partial and spot metering versions. There are also evaluative zone or matrix meters too, and these are capable of breaking an image into recognized regions and performing complex metering from all of the light in the scene. The general problem or flaw with any system is that the light is reflected, and the camera is only giving its “best guess” as to the actual amount of light striking the area being metered. Things get very complicated when the scene is similar in hue and tone, or when there is a true diversity of brilliance and highlights.
Where meters are concerned, the whitest regions are those that are given the most weight in terms of exposure settings. Unfortunately, all meters are standardized and look a light in terms of “middle gray”, and this is where some trouble starts.
For instance, consider the problems with photographing snow scenes in the midday sun…they often have a bluish cast or even a gray one due to the way the light is reflecting into the camera’s meter. They can also have some of the areas of the photograph over or underexposed due to the brilliance of the brightest white.
This is particularly true if the meter does not provide any sort of zone or evaluative options and just uses the center-weighted approach that takes a very broad look at the light in the scene. This is a good illustration at how the high-end DSLR models tend to vary greatly from the consumer point and shoot versions. Though many inexpensive models are introducing complex metering zones and options, for the most part they are limited in how much division and metering is possible in a given image, and also in how their autofocus systems override the meter’s capabilities too.
The solution to the problem has been answered by the creation of the different types of meters, as described above. For instance, the camera that allows the photographer to spot meter the area of true significance or most important light is going to get the results desired. Consider a photograph of someone on the beach, with the sunlight and bright sand behind them. A center-weighted meter would expose for the white sand and leave the person in silhouette or shadow, but a partial metering capability would allow the photographer to use the face or torso of the subject to create the best settings.
Now that we understand the significance of light, meters and exposure in a photograph we can consider times when light is more beneficial to the needs of the image. For example, there are times of day which are commonly referred to as the “sweet light” hours. These occur around dawn and dusk and are preferred moments of lighting because of their absence of harshness, shadows and extremes. If you have ever seen a photograph of a beach at sunset or even at dusk you will know right away that this was a superior time for taking the image rather than the hours around midday. This doesn’t mean that such images can only be taken in the softer and cooler light of the sweet hours, but it is a good illustration of how to select the sort of lighting required for the greatest effects. Metering and camera settings can only control a certain amount of light, and the rest is up to the photographer to arrange accordingly.
Of course, time of day is not the only way that light or color temperatures affect an image, and there is always the issue of white balance to consider too. This is something that any photographer can usually adjust within their camera’s settings, and it tells the camera how best to interpret the color temperature of the actual light source. Even though our eyes are properly interpreting the scene in front of the lens, the digital camera’s automatic white balance might be seeing it all wrong.
To compensate for such problems the better cameras will have the ability to use an auto white balance, custom (which requires the photographer to first use a gray reference and then rely on that as the white balance setting), tungsten, fluorescent, daylight, flash, cloudy, and shade mode. These settings have all been designed using very formal numeric assessments of actual color temperatures, and they don’t always apply specifically to the scenarios they describe.
For instance, any image that appears too cool in the camera’s LCD display can be warmed up by selecting the next lowest white balance setting – for instance if a daylight photograph is too cool in overall color, the photographer can adjust their white balance to flash or cloudy to see if this warms it up. This action will result in a generally warmer temperature assigned to the white light, and this tends to generate more realistic results. Clearly it will take some practice to master, and not all point and shoot models offer the full array of white balance settings, but it is well worth some effort.
Now that we have considered how the camera sees and interprets light, and discussed a few good ways to ensure we get the best light and camera response possible we can begin to approach any standard or creative photographic work with more options and control.