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Raise a hand if you spend a lot of your time in your camera’s auto modes, Program, Shutter or Aperture Priority or even Scene Modes. Keep your hand raised if you would like to shoot manually, but either A, Do not have enough time to set it up or B, still a little perplexed by manual exposure. If you have answered yes to either of these questions, perhaps its time to look at exposure compensation, the easy way into manual exposure.
So what is exposure compensation?
Well put simply it allows you to incrementally adjust the camera’s exposure around the default reading that meter is giving. Nearly all DSLR’s and advanced compacts have this feature to some extent. Some are limited to changes of ½ a stop or 1 complete stop at a time, professional level cameras will allow you to define the amount of compensation from 1/3 of a stop to 1 stop and make changes of up to 5 stops either way.
How does it work?
Well let’s assume you are shooting in aperture priority. You have chosen your aperture based on the subject matter but find that your image is constantly dark. By adding +1/2 or +1 stops via the exposure compensation on your camera you will lighten the image overall. When in aperture priority, because you want the aperture to remain the same, the camera will use a slower shutter speed to compensate.
Conversely in shutter priority mode, the camera will open the aperture, allowing more light to reach the sensor (or film). The reverse is true if you are finding your image is too light, dialing in a minus exposure compensation number will darken your image incrementally.
So what happens if I use a program mode I hear you cry? Well different manufacturers have different ways of dealing with this but generally they will compensate using a combination of shutter and aperture. It can also be used in manual mode, here, the camera’s meter indicator will show the correct exposure as being the compensated exposure.
So, why should I use it?
Well there are several reasons, but they all stem from the camera meter’s ability to determine exposure. Today’s camera meters are fantastically accurate for most things, but they can still get it wrong. A classic example, is snow, because the camera’s meter expects a scene to be the electronic equivalent of a mid grey, when you throw in huge amount’s of white, it under exposes. Dialing in a plus compensation will lighten the image and whiten your snow to a more natural appearance.
Another classic example is photographic birds or aircraft in flight. Even the best exposure meters will generally expose for the sky leaving the bird or plane dark in comparison. Again dialing some plus exposure will lighten up your subject although possibly at the expense of a washed out sky. A typical example that may over expose is a forested landscape; the darkness of the trees can very often trip up a meter. Here, using minus compensation will help correct exposure.
Adding 2/3rds of a stop compensation has brightened the image and maintained detail in the penguins feathers
So, how much compensation should I use?
Well there is no firm answer to that, it will vary from shot to shot, scene to scene. One thing I would recommend though is learn to NOT trust your camera’s preview screen. They should only be used as a very rough guide to exposure and composure, no more. Perhaps the best way of checking you have the correct amount of exposure compensation is to use your camera’s histograms. Learning how a histogram work will make both exposure compensation and indeed manual exposure become second nature with a little practice.
Lastly, how do you find the exposure compensation setting on your camera? Well the manual is your friend here, different cameras have different systems from a simple dial on the camera top plate, through a button/dial combination to being buried in a menu selection. Wherever yours is, take some time to understand how it works and you be halfway to understanding manual exposure.
Jason Row is a British born travel photographer now living in Ukraine. You can follow him on Facebook or visit his site, The Odessa Files. He also maintains a blog chronicling his exploits as an Expat in the former Soviet Union