Stop Thinking Like A Film Photographer
When I say “Stop Thinking Like A Film Photographer”, I don’t mean you should forget everything you knew back in those days. All of the principles of photography (as you will see in the article) and of art still apply. What I mean is “stop restricting yourself”. By adapting slightly to take full advantage of your new capabilities, you should become a better photographer.
It’s been thirteen years since Canon came out with the first affordable digital single-lens-reflex (DSLR) camera*, but we are still thinking as if we were back in the days of film. There are not two, but three parameters you can control to match the level of light to the capabilities of the recording medium, which is your primary concern.
- You can control the aperture, or the size of the hole letting light onto the medium,
- You can control the shutter speed, or the length of time the shutter is open and letting light onto the medium, and
- You can control the sensitivity of the medium to the light it receives.
Back in the days of film, the sensitivity (referred to as film speed and given as an ASA number (from the American Standards Association)) was a characteristic of the type of film used. Once you made your choice at the store and placed the roll of 12 to 36 exposures in the camera (which in today’s cameras could take you less than two seconds to use), you were stuck with that choice for a good part of the day and it was no longer a part of your considerations. At the time of the shot, the photographer wrestled with striking a balance between the remaining two factors, where the decision was often reduced to which type of blur (motion or focus blur) would be the most damaging. That mentality is still with us, and is reflected in the advanced exposure modes that camera manufacturers offer us.
Why The Struggle?
Each of these three controls has a side effect. Most of these side effects have artistic consequences.
- The aperture also controls the depth of field. The smaller the hole (as expressed by a larger f-stop), the larger the distance in front of and behind the subject that will also be in focus. A larger depth of field is often good for landscapes and in cases where you may need to cover your butt so that distance uncertainties don’t put the subject outside the area of focus and ruin your shot. On the other hand a small depth of field is useful for blurring a busy background when you want the viewer to focus only on the subject.
- The shutter speed controls motion blur; less time open means less blur. Although frequently blur is a bad thing, sometimes it is a good way to represent action in your picture. You may need a little blur in the hummingbird’s wings to prove to your viewers that you didn’t just hang a stuffed bird by a string (which would usually be much easier than trying to capture a live bird’s picture in the wild).
- The higher the sensitivity, now called the ISO (for International Standards Organization), the more noise (analogous to grain in film photography) you will have in the picture. Unlike the other two side effects, this is almost never considered a good thing artistically.
Although there is no way to eliminate sensor limitations, you can avoid the camera’s programming/software limitations if you make all of your own decisions and set all three of the above described parameters on your own. That’s why I highly recommend using manual mode wherever practicable. There are situations, however, when because of rapidly changing light conditions, you might need to let the camera make some of the decisions for you. Be aware, there is a price for this convenience.
At the other end of the spectrum of shooting modes is Auto mode. Sometimes it has special flavors like sport, snow, portrait, etc., where you can give the camera a hint at what type of picture you are interested in. Then the camera makes all of the decisions. Unfortunately, the computer in the camera is only capable of controlling one variable reasonably well. Therefore, you should stay away from fully automatic or Program mode. Never let the camera make more than one decision, and even then be very careful.
In most digital cameras there are only two advanced exposure modes left to choose from. Assuming that you are going to set your ISO in advance (just like the old days), the camera gives you the choice of setting the shutter speed (called Shutter-Priority Mode) or the aperture Aperture-Priority Mode), and letting the camera set the other. In truth, since now each of the three parameters is equally easy to change, and equally critical to a good picture, all three should be considered equally in the shot planning process. Maybe these modes should be named for the one decision you let the camera handle instead of the “most significant” of the two parameters you still control. In virtually every instance, it would be better to let the camera handle the one parameter whose side effect has the least artistic impact - ISO. Instead of picking your poison, as in the days of yore, you should be able to set both the shutter speed and the aperture, and let the camera pick the smallest ISO that would make the shot work. And just like the other two modes, you should be able to use exposure compensation to correct for the camera’s poor judgement. Only recently has that third option become available. For Canon cameras, that third mode is called Manual Exposure with Auto ISO. I understand it is also available in Nikon and possibly other cameras. Few people yet realize that this is probably your best option (after Manual mode).
The Cost Of Convenience
Another thing that not everybody seems to realize is that once you let the camera control even one of the three parameters, you lose virtually all control over the exposure; you are now only controlling up to two of the three side effects (motion blur, depth of field, and/or noise). On a recent trip to Africa, a fellow tourist was using Aperture Priority, but the shot was overexposed. The tour guide gave her the same advice he would give in Manual mode; go to a higher f/stop (smaller hole) to restrict the light. Obviously, he didn’t advise changing the shutter speed because in Aperture Priority you have no control over shutter speed. Unfortunately, his advice was doomed to fail. Even though the photographer controlled both the aperture and the ISO, neither could solve this problem because the camera was still able to overcome her changes by slowing the shutter speed to achieve what it still considered the proper exposure. Her next picture had a larger depth of field, and the birds flying through the background were longer fuzzy blobs than in the first picture (when she set the camera on Aperture Priority she told the camera she didn’t care about that part), but the brightness of the picture remained the same. When you are in one of the advanced modes and have given the camera the last word in exposure, the only way you have of affecting your histogram is to use exposure compensation. Although the camera treats this as a suggestion, it will usually solve the problem. If it doesn’t, you have no choice but to shoot Manual. In this case, my fellow tourist should have tried a negative exposure compensation, asking the camera to reduce the light hitting the sensor. The camera would have done that by increasing the shutter speed (letting in less light).