19 Jun 2011

Why you should shoot in manual mode

Posted by dap

If you’re like most amateur photographers, you spend most of your time shooting in one of the semi-automatic exposure modes: program auto (P), aperture-priority (A), or shutter-priority (S). In this post, I’ll make the case for trying out shooting in fully manual mode (M).

If you’ve used M a lot already, or if you’ve never taken your camera off fully-automatic, then this post isn’t for you. For the rest of you who use P, A, or S, my claim probably sounds crazy. When I bought my DSLR, I barely considered M. I viewed it as a useful feature for when I might someday want that level of control, but I figured it would be hard to use and that if I got to the point where I needed it, then I’d probably know how to use it. I changed my mind after hearing a professional photographer recommend that beginners start with M early on because it forces students to more deeply understand the tradeoffs around aperture and shutter speed. That’s a fine reason, and an important side effect of using M, but the main reason I primarily shoot manual now is much more compelling: I find it much simpler than the alternatives. That’s partly because M is simpler than I thought it would be, and partly because P, A, and S are harder than I realized.

Manual is not as hard as you think

Most online resources and camera manuals describe these shooting modes something like this:

  • Program auto (P): you choose from various combinations of shutter speed and aperture that produce a “proper” exposure (as determined by the camera’s meter)
  • Aperture-priority (A): you choose the aperture, and the camera chooses the shutter speed that will produce a “proper” exposure (as determined by the camera’s meter)
  • Shutter-priority (S): you choose the shutter speed, and the camera chooses the aperture that will produce a “proper” exposure (as determined by the camera’s meter)
  • Manual (M): you choose both shutter speed and aperture.

But it’s important to remember that in all of these modes, the camera’s built-in meter figures out what it thinks is a proper exposure, conveys that to you, and lets you make the final choice. Even in manual mode, you still see the camera’s meter, so you can tell if your current settings match those the camera would pick. If you want to play with M, it’s very easy to take the exact same photos you would take in the other three modes by simply tweaking the settings to match the camera’s recommended exposure. The only difference is that you’d be spending more time getting the settings right, but there’s nothing “harder” about it since you’re just moving the dial until the camera meter reads “correct exposure”.

Oklahoma City Memorial

Oklahoma City Memorial

The semi-automatic modes are not as easy as you think

A lot of people believe the first three modes, sometimes called semi-automatic modes, are simpler than M because there are fewer parameters. In A, you don’t worry about the shutter speed, and in S you don’t worry about the aperture. In M, you have to worry about both, and many beginners aren’t comfortable with that yet.

That’s a fair summary when the camera meter is correct. But it often isn’t. In fact, many more of my photos than not are taken with slight changes from the camera’s recommended exposure. In the semi-automatic modes, you can tweak an invented parameter called “exposure compensation”, which basically overrides the camera’s recommended exposure by biasing it in one direction or the other. For example, if the camera thinks there’s less light than there actually is, the default setting would over-expose the image. In that case you’d add negative exposure compensation to cause the camera to pick an exposure closer to what it should be. In manual mode, you just adjust the aperture or shutter speed, which is what you’re already doing.

Besides that, I found that in aperture priority mode, I often wound up with a shutter speed that was too long and allowed visible motion blur. Similarly in shutter-priority, I’d wind up with an aperture that was too large, giving too little depth of field and an overall unfocused image. Both of these effects are much worse than underexposure. I learned what in retrospect is obvious: shooting in aperture or shutter priority doesn’t enable you to ignore the other variable. The camera’s not magic.

Considering these two points, you might more accurately describe the four modes like this:

  • Program auto: you choose (1) exposure compensation and (2) which one of the camera’s aperture/shutter speed pairings to use.
  • Aperture-priority: you choose (1) exposure compensation and (2) which aperture to use. (But in the back of your mind, you still have to worry about (3) the shutter speed because of motion blur, though admittedly not as much.)
  • Shutter-priority: you choose (1) exposure compensation and (2) which shutter speed to use. (But in the back of your mind, you still have to worry about (3) the aperture because of depth of field, though admittedly not as much.)
  • Manual: you choose (1) aperture and (2) shutter speed.

The way I see it, in each of these modes, you really have to choose at least two variables. In manual mode, both variables are concrete: I can understand the impact of changing aperture and shutter speed. With the semi-automatic modes, you have this synthetic “exposure compensation” parameter, and I always found myself unsure how to manipulate it. And since you can’t truly forget about the other variable, in a sense you now have three variables to consider.

Small Stream in Muir Woods

Manual all the way?

If you believe everything I’ve said so far, you might now wonder why you would ever not use manual mode. Of course, there’s a reason these other modes exist. Even if you know what you’re doing, it takes longer to set exposure in M than P, S, or A. By definition in the semi-automatic modes you’re starting from something close to correct and fine-tuning it, while in M you may be all over the map.

If you’re shooting static subjects like landscapes, nature, or studio subjects, and you have a lot of patience, shooting in M probably makes a lot of sense. If you’re shooting sports, street photography, or night photography, your ability to take a shot at the right moment is much more important than nailing the exposure, so the semi-automatic modes make a lot of sense. (It would be a pretty cool feature to have a button in manual mode that reset the exposure to one of the valid P modes so you wouldn’t have to waste time getting the exposure in the ballpark.)

With all of the above understood, I’d phrase the choice like this:

  • Program auto, aperture-priority, and shutter-priority: let the camera pick a good starting point for the exposure, but then fine-tune it. Expect that you will be adjusting exposure compensation on most shots.
  • Manual: you get the camera’s advice about the exposure, but you set it from scratch.

In the end, it’s your choice

Like so many things in photography and life, I started on one side of this (using semi-automatic mode), switched over (using manual mode almost exclusively), and now find myself somewhere in between. But the difference is I’ve got a much better understanding than before. Like the photographer I mentioned above, I recommend playing around with manual mode (extensively, not just for an afternoon) if for no other reason than to understand more viscerally what the camera’s doing for you in the semi-automatic modes.

I still prefer manual mode for most of my shooting for the reasons I mentioned above: most of my subjects are not fast-moving, and I’m more comfortable manipulating the underlying parameters directly than trying to guess how exposure compensation will affect things. I’m also pretty willing to deal with the many incorrectly exposed photos I get by choosing wrong, since Lightroom makes dealing with all the rejects pretty easy. But lately I’ve been considering switching back to A for speed and as a convenience. The key is to still think in terms of the aperture and shutter speed, not exposure compensation. So if nothing else, my manual approach has helped me understand much better how to shoot in P, A, and S.

In the end, it’s all about results. I’m curious to hear how you prefer to shoot! Leave your comments below.

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