This topic may sound dry as a bone but exposure compensation is one of those things I wish I had figured out a lot earlier in my photography experience. As a beginner photographer I was just excited to get out and use my camera, so I basically got it out of the box, put it in auto mode, and began taking pictures. That was great for a while but soon I was itching to have more control and use more of its functions. The next step for me was Aperture Priority mode. It allowed me to start taking more control over my camera, without the complexity of Manual Mode.
And that's where exposure compensation comes in handy. This valuable tool allows us to shoot in aperture priority mode but still fine tune the exposure! Awesome, right? Read on to find out how.
Before I dive into the exposure compensation piece I wanted to quickly review a few basics of exposure. When you take a picture there are three components involved in exposure: aperture, shutter speed, and ISO. Aperture is the opening that allows light into your lens. Wide apertures allow lots of light in and are indicated by small f-stop numbers like f/2.8. Narrow apertures allow much less light in and are indicated by large f-stop numbers like f/18. When I shoot, aperture is typically my priority. I choose the aperture for creative reasons and if I am using aperture priority mode (A or Av), the camera then chooses the correct shutter speed to expose the photo. ISO is another adjustment and I'll cover that elsewhere. In most situations, your camera's processor is very smart and your image will be exposed properly. In some cases though it's not quite right, a tad dark or light, and this is where exposure compensation is incredibly useful.
Now to the heart of the matter - exposure compensation is a function of your camera that allows you to adjust the automatically calculated exposure. This is an easy way to correct a poorly exposed photo in small increments. When you take a picture and still are not quite satisfied the brightness of the final image, this tool allows you to make fixes quickly on the fly.
On many cameras this feature is indicated by a +/- button on the top of the camera. By holding this button down (or pressing it - depending on your model of camera), you can turn the dial to adjust the exposure in the positive or negative direction. Most cameras are capable of adjustments ranging from -2.0 on the left to +2.0 on the right. If you adjust exposure in the negative direction, the next picture you take will be darker without making any additional adjustments. On the flip side, if your image was too dark to begin with, you can adjust the exposure in the positive direction. The adjustments you make in either direction are typically in 1/3 stop increments - a throwback to film photography days.
For whatever reason it took me a long time to discover and begin using this feature. If I took a picture that was not properly exposed, I basically went back to the drawing board and began tweaking all of my settings to change the outcome. This was tedious and slow and did not produce consistent results because I wasn't really making changes in any kind of systematic way.
Once I discovered exposure compensation I was able to choose my settings and take a photo, view the photo on my camera's screen, and then use the exposure compensation button to make slight changes in either direction. Hallelujah! With a button push and dial twist I could nail the exposure even in difficult circumstances. I also discovered that particular lenses seem to always be a bit over or underexposed for my taste, so I use exposure compensation with that particular lens as a matter of routine.
When Your Camera Gets Confused
There are lots of times that your camera may be a bit confused and not quite expose the photo properly. Some examples are snowy scenes, backlit situations, scenes with areas of both sun and shade, and black objects.
With a snowy scene your camera treats all of the white it "sees" as middle gray. The result is that beautiful, white fluffy stuff can look dull and gray. In order to get pristine, white snow, tweak the exposure. A simple way to do it in aperture priority mode is to choose your aperture, take the photo and view it, and then use exposure compensation a position or two in the positive direction. Take another picture and continue adjusting until the snow looks crisp and white. Be cautious as you are increasing exposure that you don't go too far. If you overexpose your image, you will have blown highlights and lose detail. The picture below would benefit from exposure compensation in-camera in the positive direction to whiten and brighten it up.
Snow in Angels Camp by Flickr user Isolino
With proper exposure even tricky snowy scenes can look amazing.
A scene like the one below is also difficult for your camera to expose correctly. With both shade and light in the composition, it exposes for the brightly lit area resulting in the shaded parts being too dark. This is another case where exposure compensation is a handy tool while shooting. If you set up a similar image and find it is too dark, again use your exposure compensation button in the positive direction to lighten it up.
Now that you have this handy tool at your disposal, get out and take some shots. No more head scratching. In those tricky light situations, use it to simply adjust exposure while you shoot. No complicated menu choices or multiple steps…just dial it up or down!
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