Choice of exposure mode always seems to generate a spirited discussion among photographers. Here’s my 2¢ about it. Actually, it’s a long post (probably more like 4 or 5¢), so you might want to grab your favorite beverage before settling down in the warm glow of your monitor.
If you’re serious about your photography, you’ll need to use Program, Aperture Priority, Shutter Priority, or Manual exposure mode. Neither a fully Automatic mode nor any of the “Scene” modes found on many DSLRs allows you to override what the camera chooses for you.
A camera’s meter is designed to determine the exposure that renders the scene as a mid-tone. But the actual scene may require a darker or lighter exposure than that.
As with any other element of your photography, the correct exposure for a particular image is the one that shows the scene as you intended. This might be, and often is, different from what the camera meter indicates.
Shutter Priority, Aperture Priority, and Program are known as automatic modes because the camera automatically sets the aperture, shutter speed, or both, respectively, based on the camera’s meter reading. In Manual mode, you set both the aperture and shutter speed, using the camera’s meter as a starting point.
You can successfully use any of these modes (why else would they be there?), but it’s worth finding one or more you are most comfortable with. I exclusively use Manual mode. I find it the easiest and most consistent for the kinds of photography I do. But I hope this discussion helps you choose the one that works best for you.
By the way, this image has nothing to do with this article. But a picture of my best furry friend Fredo sure makes this a much more attractive post, doesn’t it?
For rapid shooting in average light, you can use Program mode. In this mode, the camera chooses both aperture and shutter speed to give an average exposure. Many cameras allow exposure compensation in Program mode to fine-tune that exposure. I don’t ever use Program, so can’t say too much more about it.
Shutter Priority could be your choice when shooting action such as sports, birds, and wildlife. Less frequently, you might choose a very slow shutter speed to show motion blur. In Shutter Priority mode, you set the shutter speed, and the camera sets the aperture based on its meter reading. Exposure compensation brightens or darkens the image by respectively opening or closing the aperture, while holding your chosen shutter speed constant. I don’t use this mode either.
Aperture Priority is probably the most popular automatic exposure mode. You choose the aperture, and the camera chooses the shutter speed based on its meter reading. Exposure compensation brightens or darkens the image by respectively decreasing or increasing the shutter speed, while keeping your aperture the same. As I’m sure you’ve guessed by now, I don’t use this mode either.
In Manual mode, you choose both the aperture and shutter speed, using the camera’s meter reading as a starting point. There is no exposure compensation, because it’s up to you to set both the aperture and shutter speed independently. The camera makes no settings itself, regardless of what its meter reads.
Here’s why I like Manual mode. Whether I’m shooting wrecked vehicles and accident scenes for my work, or landscape and travel images for myself, I think in terms of what aperture and what shutter speed would best tell the story I want to tell in each image.
For example, if I’m shooting a landscape on a breezy, overcast day, I might want f/16 to keep everything apparently sharp from the foreground to the background. But then the shutter speed suggested by the meter might be too slow to freeze the motion of the leaves on the trees.
I now have a few options. First, I could decide that the image would still work if I open up the aperture to get a faster shutter speed. Or I could raise my ISO to keep my aperture stopped down while getting a shorter shutter speed. Or I could decide to underexpose the image by leaving the aperture where it is, and raising the shutter speed anyway. Or I could do a combination of any or all of them, depending on how I think they will affect the final image.
Thinking about the specific aperture, specific shutter speed, and specific ISO helps me to decide how I want to proceed when exposing in Manual mode based on the camera’s meter. I find it easier to manually adjust the exposure over or under the meter reading by thinking of those individual values, then rotating the front, the rear, or both command dials, rather than by using exposure compensation in any of the automatic modes.
Regardless of your preferred exposure mode, there are times when Manual mode is much easier, if not essential.
If you are shooting multiple frames to stitch together in a panoramic image, you must use Manual mode, along with manual focus and manual White Balance. Any frame-to-frame variation will make it difficult, if not impossible, to seamlessly blend individual frames into the finished image.
If your subject is partially in sun and partially in shade, or if your subject is in shade and the background is bright, or vice versa, a shift in camera position would likely cause a change in the camera’s meter reading. In one of the automatic modes, this could result in some areas of the image becoming over or underexposed just from repositioning the camera, even though they were properly exposed previously. In Manual mode, the meter reading changes, but the exposure stays the same, regardless of camera position, unless you change it yourself.
Here’s an example. Let’s say your subject is a sidelighted white marble statue. Your initial composition has 1/2 of the statue in sun, and 1/2 of it in shade. Your camera’s meter indicates both the sunny and shady surfaces will just barely be properly exposed in a single frame.
Now you decide to recompose the image so that 3/4 of the statue is in shade, and only 1/4 of it is in sun. The meter now sees more dark in the image than it did before, and will accordingly suggest an increase in exposure. In one of the automatic modes, unless you use exposure compensation, the sunny part would then be overexposed. In Manual mode, even though the meter would indicate an underexposure, the actual exposure would remain the same as previously.
In one of the automatic modes, there are several things you could do. All of them require more effort and button presses than Manual mode (where there would be none).
You could push the shutter half way down to lock the exposure, then recompose the image. But that would also lock the focus, too, unless you’ve decoupled autofocus from the shutter button (as I have). This can be cumbersome, especially if you’re working on a tripod.
You could recompose to get the original exposure, then press the Exposure Lock button, and then recompose while holding that button in. Again, this can be quite cumbersome.
You could use exposure compensation by pushing the Exposure Compensation button while rotating one of the control dials until you get the previous exposure back. For those of you who shoot in one of the automatic modes, this has likely become second nature. The advantage of this method is you don’t have to hold in any of the extra buttons you have to press.
Here’s something else to think about if you use the automatic modes. If your camera is on a tripod, and you take your face away from the eyepiece, light can enter there, and affect the meter reading. This won’t change anything in Manual mode, but will actually alter your exposure in one of the automatic modes. (Blocking the eyepiece before tripping the shutter will prevent this, as will shooting in Manual mode.)
As long as you consciously think about your exposure, any mode can be used successfully. For me, the ease and the predictability of the results of Manual mode have made it the only one I use.