Right after learning how each of the shooting modes works on your camera, a natural question you might ask is “how do I know which mode to use?”
Here is a simple decision tree that can help you move your camera off of Auto and onto the right priority setting.
Question 1 - Is my subject moving?
If you know that Shutter Priority is used to show motion or movement and Aperture Priority is used to show depth of field, your first question should help you decide between the two. ‘Is my subject moving’ is a great first step.
If the answer is ‘Yes, my subject is moving’ then you would likely shoot in Shutter Priority mode. That is the “S” on Nikon cameras and “TV” on Canon cameras.
If the answer is ‘No, my subject is not moving’ then you would select Aperture Priority mode, “A” on Nikon cameras and “AV” on Canon brands.
Once you’ve decided your priority shooting mode, the next questions on your decision tree help you decide what end of the dial to select.
Question 2 - (If you selected Shutter Priority) Do I want to freeze the action or use a blur to show motion or movement?
If you want to stop action the way sports photographers do, then select a fast shutter speed. You can safely choose one that is faster than 1/1000 of a second.
If you want to show motion or movement, then you need a slower shutter speed. This is where it can get tricky. A slow shutter speed will depend on the focal length of your lens. The more you zoom in, the more your camera shows movement in your pictures. Generally speaking, you choose a shutter speed that equals your focal length to avoid camera shake.
That means, if I am zooming to 100 mm, I want to shoot at 1/100 of a second to hold the camera and avoid shake. I think that’s also a good place to begin experimenting with showing motion blur. If you use a tripod, you can go much slower with more dramatic results.
Question 3 - (If you selected Aperture Priority) Do I want to show everything in focus or just a shallow area around my subject?
We use Aperture Priority creatively to show depth of field. You will decide how much of the area around your subject you want in focus. If you just want your subject in focus, that’s called a shallow depth of field. It helps your viewer focus on your subject without any distractions from the background. For this effect, you select a lower number in your F-stop or aperture setting.
When everything is in focus, like a landscape scene, you are shooting a long depth of field. You select a higher number in your F-stop or aperture setting.
I’ve found this decision tree is a good starting point for photographers who struggle deciding which priority setting to use. Nothing is absolute, however. There are times when your subject isn’t moving, and you will want to still use Shutter Priority.
In some low light situations, I might select Shutter Priority to make absolutely sure I don’t end up with a slow shutter speed that gives me camera shake. At that point, the risk of a blurry photo is my primary concern and outweighs any depth of field considerations. I’m not likely to get enough light with a small aperture setting anyway.
Exceptions aside, the three questions in this decision tree can help you quickly decide which camera setting to use in most situations. Once you start in those settings, you can experiment and branch out, but at least you’ll start with confidence.