With few a simple changes to the basics settings you can make your DSLR or mirrorless camera much easier to use, with the added control of exposure compensation. In this tutorial we'll look at how, and why you might want to.
Exposure Compensation is a way to override or compensate for the automatic exposure settings chosen by the camera, to make your photograph brighter or darker. It's an underrated, misunderstood feature of most cameras,and it has lots of creative potential.
Auto Exposure, Auto-ISO, and Exposure Compensation
Using Automatic Modes
If you’re using an automatic or semi-automatic mode like a P (Programme), A (Aperture-Priority) or S (Shutter-Priority) mode, or another pre-programmed mode, then typically you’ll choose some settings and the camera will automatically adjust the rest for optimal exposure.
For example, imagine you are photographing in quite bright light. In A mode, you’d choose your aperture and the camera would adjust the shutter speed and possibly ISO to make sure you aren't under- or over-exposing the image.
It’s worth remembering that if you’re using S mode, there's such a range of shutter speeds available that it’s possible to choose one that the camera can’t possibly compensate for adequately with its aperture choice. If you were in a dark room and you chose at a very fast shutter speed, the minimum aperture the camera has available to it might not be enough to light your image, and you’ll get a warning.
On-the-Fly Exposure Adjustment in Auto Modes
Exposure Compensation means you can further adjust how your image looks very quickly, without having to go into adjusting your camera settings manually. With a single change, you can brighten or darken your image in a way that preserves the balance in your settings, and it works in increments.
You might want to make changes for practical reasons, like a darker foreground where your camera has exposed for a brighter sky in the background, or for artistic reasons to deliberately make your image brighter or darker.
How it works will depend on what camera and setting you're using.
Let's take aperture-priority again as an example. As usual, you'd set your aperture, and the camera would choose the shutter speed. But you decide, using your histogram and the preview image on the back of the screen, that maybe the exposure could be a little bit brighter. Instead of taking your camera into manual settings, you can adjust the exposure compensation value, or EV to tell the camera to increase the exposure the shutter speed, and possibly ISO, to give the exposure you want. It's quick and easy, and you don't have to change camera modes; you get a little extra control and the benefits of auto.
How to Find Exposure Compensation on Your Camera
Not every camera has an exposure compensation button, but many if not all have it in software menus. It's much more useful as a physical button.
Many cameras will have a button with a plus and minus sign on it, circled above.
When you hold that button, you can use your menu navigation buttons or wheels to scroll through your options. On the Nikon I have the choice of -1.0, -0.7, -0.3, 0.0, +0.3, +0.7, +1.0. Each turn of the wheel will usually change your exposure by 1/3 of a stop. If you're using a Canon camera, your button might be on the back of the camera marked AV, or you might be using a camera that doesn't have a button, but instead has another wheel that you can just turn without needing to press anything at the same time.
How to Choose an Exposure Value
As mentioned, the Exposure Compensation option lets you adjust it in increments and it might take a little while of you using it before you can instinctively know which option will give you the desired result. Until then, you can use your eye with your original image, judging whether it could do with being a little brighter/darker or a lot brighter/darker as well as using your histogram to help.
The default will be 0 (no change), and you can cycle up or down through increments to choose your exposure. In the last photo, you can see I've chosen +1.0 which is equivalent to one stop brighter than the value selected by the camera. + numbers will brighten your photograph, - numbers will darken it.
Exposure Correction in Practice
0 Exposure Compensation
I chose the example above as it's got a bright sky and a dark foreground, so it's trickier for the camera to know what a 'good' setting is. In A (aperture-priority) mode, I chose f/8 to keep everything in good focus and the camera then set the shutter speed (1/125) and the ISO (320). You can see it's exposed for the sky, preventing it from blowing out but at the expense of making the foreground very dark.
+1 Exposure Compensation
In this example I've used the same settings the the previous image, but this time with +1 exposure compensation. This adjustment to the EV (exposure value) meant the camera changed the shutter speed to 1/50. This is obviously too much as it's blown out the sky, but you can really see the difference in the foreground here.
+0.7 Exposure Compensation
This example is +0.7 exposure compensation and I think it's our 'Goldilocks' sweet-spot for this particular image, the sky doesn't have the detail that the original image captured, but you can see from looking at it by eye (and confirmed by the histogram) that there's no lost information there, so it'll be recoverable in post-processing. What we have instead is an increased level of detail visible in the shadows, and again that's something that can be improved more if needed, in post. This is the best exposure, technically.
Exposure Compensation is a great way to use your camera in a semi-automatic way but while retaining some control over your image without needing to shoot fully manual. Remember that whatever mode you're in means you'll select that particular setting and the camera will choose the rest. If that doesn't work for the image (or for you, artistically) you've then got the option to make the photograph brighter or darker, by changing the exposure compensation value. The camera will do this by tweaking the 'auto' setting that you aren't controlling. If you're in A mode, then exposure compensation will affect the shutter speed. If you're in S mode, exposure compensation will affect the aperture. In P mode, you'll have to check your particular camera and what it's set to do, but it'll adjust either aperture or shutter speed - for my Nikon D800 it's the latter.
Exposure Compensation is really useful for scenes of high contrast because you can decide what you want to be exposed. Quite often, for things like bright skies, the camera will adjust for that and you might be left with the thing you were actually photographing in the foreground, looking quite dark. A tweak to the EV can make all the difference. It's also really useful in snowy scenes when metering can be a nightmare, plus for things like portraits if you've got your subject against a bright background or window.
Finally, you can use Exposure Compensation to merge several images into one 'perfectly' exposed one. There's another feature that can help with this called Auto Exposure Bracketing.