Here we will quickly go through the modes on the mode dial on your camera. We’ll talk about them in the order of least control to most control by the photographer.
Auto Mode: This mode is known among snooty photographers as “Idiot Mode.” When you use this mode, you essentially turn your camera into a point and shoot (although with better image quality due to the bigger sensor). In this mode, the computer in your camera controls every setting on your camera and your are powerless to do anything about it.
Don’t use this mode. If you really want the computer to set everything for you (which I don’t recommend), use Program mode, which is discussed next.
Program Mode: In this mode, the computer in your camera sets all the exposure settings. However, if you wish, you can adjust the aperture or the shutter speed up or down. When you do that though, the computer will make a corresponding adjustment to keep the exposure where it thinks it ought to be. In other words, if you shorten the shutter speed by one click, the computer will open up the aperture by one click to offset the change you just made and keep the exposure the same.
Usually, on a different dial or sometimes in the camera menu, you can also tell the camera to underexpose or overexpose as well. This is referred to as Exposure Compensation. This gives you additional control over the camera. It applies in the next two modes listed here too.
If you don’t understand exposure yet or you are just not comfortable operating the camera settings on your own yet, you can use this mode. The computer won’t let you stray from an automatic exposure so your picture should be ok, but you can adjust the aperture or the shutter speed as you gain a little confidence with your camera. You should make it a priority to move on to Aperture Priority Mode or Manual mode as soon as you can though.
Shutter Priority Mode: I’m not going to dwell on this mode because nobody uses it. Basically, you set the Shutter Speed and the computer sets the Aperture. I suppose it could have some application where you absolutely must use a given shutter speed, but that is pretty remote and in any case there are other ways to do that. Forget about this mode.
Aperture Priority Mode: Along with Manual, this is one of the modes commonly used by advanced photographers. You set the aperture, and the computer in your camera sets the shutter speed.
Since the aperture is paramount in determining your depth of field, many photographers want to concentrate on that and just let the computer take care of shutter speed for them. So this mode makes a lot of sense. It is often described as the best of all worlds; which is control by the photographer where it matters (aperture) and the speed of a computer where it usually doesn’t (shutter speed).
Of course, sometimes shutter speed matters. But it is a simple matter to move the aperture setting with an eye on the corresponding change in shutter speed made by the computer.
I should mention that the photographer will always set the ISO in this mode as well.
Manual Mode: It is just like it sounds. The photographer has full control over the aperture, shutter speed and ISO. The computer will offer no guidance.
Many advanced photographers use this mode. It helps you master the camera, and once you get used to it you can move pretty quickly. The down-sides are that you cannot adjust the settings as fast as the computer, and there are times you will forget to change a setting.
That’s it for the descriptions. You should have a good handle on the camera modes now. To drive it home, however, I offer you an analogy.
You Control the Future of Humanity
As you know, most end of the world sci-fi stories involve humans ceding a little too much control to the robots until one day the robots wonder why they need these pesky humans around and take over (think The Matrix or The Terminator). There is much to learn from these movies for your photography. When it comes to your camera, don’t cede too much control to the robot in your camera. You never know, it might take over. At the same time, the robot can be useful and improve your life.
So, choose your camera setting, and then read below for the future scenario you have created with your choice.
Full Auto Mode: You have ceded control of the world over to the robots. Fool. All is lost.
Program Mode: You have ceded control of the world to the robots, but you have built in an override. Interesting move. Risky, obviously, but there is hope for a human takeover in the future.
Aperture Priority Mode: You are living in balance with the robots. Nice work. Don’t get too comfortable though.
Manual: Just to be safe, you have abolished the robots entirely. You could be accused of being overly conservative, but there will definitely be no robots messing up your future (photographs).
Ok, I’m just having fun here. Just to be clear, you should be working toward using Aperture Priority mode or Manual mode in all your photography. You can use other modes as a crutch if you are just getting started, but you should make a real effort to move away from them as quickly as possible.