You didn't go out and spend several hundred dollars to buy a quality DSLR camera just to set it on automatic. I want to stress the importance of learning to make your own exposures by setting your camera on M for manual.
There are several important reasons to make your own exposures. First, it's important for you to take control of your camera. Second, your photos will be better than the images made with automatic settings as you begin to understand making proper exposures. Finally, you just can't beat the pride of learning to make fine photos by using the two greatest tools available to any photographer: your eyes and your brain.
A good exposure is one that correctly exposes the pixels on your camera sensor so the image is not too light or dark. We do this with three basic camera controls. The first is shutter speed. Shutter speed controls how long the shutter is opened, exposing the pixels. Speeds might range from 1/2,000 of a second to one second or longer.
The natural shutter speeds that you should be concerned with now are 1/60 sec, 1/125 sec, 1/250 sec, 1/500th sec, 1/1,000 sec and 1/2,000 sec. You want to select a faster shutter speed to photograph fast-moving subjects, such as your kid's soccer game. Speeds of 1/500 sec and faster should do the trick. One important consideration: Don't use shutter speeds under 1/60 sec without a tripod, as blurry photos could result.
The second camera control is aperture, or f-stop. The natural f-stops are: f-22, f-16, f-11, f-8 f-5.6, f-4 and f-2.8. The lower the number, the more light that is being let into the camera sensor. If you were to photograph on a very overcast day, your f-stop might be f-4; on a bright, sunny day, more like f-22.
The third camera control is ISO. ISO controls how sensitive the pixels are to the light. An ISO of 400 makes the pixels twice as sensitive as an ISO of 200. The beauty of the ISO setting is that you can raise the ISO as the light drops, thus allowing you take photos in dimly lit situations. Always use the lowest ISO you can. As ISO settings increase, the image quality drops due to what is called noise.
Now let's pull it all together. As you look inside your viewfinder, you should see a graph at the bottom with a plus on one side and a minus on the other. Point your camera at your subject. In the center of the graph will be a midpoint mark and a bar underneath that moves from the plus side (overexposed, too much light) to the minus side (underexposed).
As you change the ISO, shutter speed or f-stop, this bar will move until it's under the mid-point mark. Take your camera outside on a bright day and find something to photograph. Set your ISO to 100. Now put your shutter speed on 1/125 of a second and your f-stop on f16. Check where the bar and graph align. If the bar is closer to the minus side of the graph, let in more light by opening the f-stop to f-11; if the bar is closer to the plus side, close the f stop to f-22. Play with your settings until you make the perfect exposure!
Keep practicing these exposure basics. My next column will deal with fine-tuning your exposures.
Jay Sousa has been a professional photographer for 32 years. Contact him at firstname.lastname@example.org.