How to use exposure compensation

June 22, 2010 Pete

Most camera’s today will have an auto exposure capability, so you may think that your camera will always expose everything correctly. Unfortunately, this is not the case, as the camera exposure system is only as good as what you direct it to expose. With my camera, the Olympus OM 4ti, the metering is centre weighted so the exposure made by the camera will be on whatever I place in the middle of the picture. This will be treated as mid toned, be that black, white, green etc (you get my drift). Another term you may hear a lot in photography is ‘mid grey’, which I feel is very misleading in today’s world of colour photography. Mid toned or middletoned I think is easier to understand.

To elaborate further, if I place a black subject in the centre of my picture, the camera will think that my intention is for this dark colour to be my mid tone, and so if I also have white or bright (highlights) elsewhere in the picture these will be blown out, over exposed. Alternatively if I was to select a white subject then this will cause darker areas to be underexposed (too dark). This may be your intention.

So you ask, what can I do in this situation? You will be pleased to know that there are several tools readily available to help. One of these is the exposure compensation tool on your camera, which for me is the auto compensation dial. This can be signified as +2,+1,0,-1,-2, normally in increments of 1/3 or 1/2 stops. For my Olympus OM 4ti it is in increments of 1/3.

How do you use exposure compensation and why would you want to use exposure compensation? Exposure compensation gives you the ability to control your exposure setting and so the range of tones in your photo, by controlling the lightness or darkness of the tone. Another way of explaining this is that it gives you the opportunity to influence the mood of the picture, adding emotion.

This is done by making the tone appear lighter or darker e.g. making the shot darker can make the scene moodier . If you open up then it will be lighter, whereas if you were to stop down it will be darker. Rather than write a whole essay I will show you an example.

It is also worth noting that this technique is not limited to the exposure compensation dial, you could also work with different apertures or different shutter speeds. For example, closing down your aperture from F8 to F11 will let less light in so making your shot appear darker or opening up your shutter speed from 1/125 to 1/60 will let more light in, making your picture lighter. Anyway I digress.

The example I will use is of a Buttercup (Ranunculus) flower taken at Kingcombe Meadows in Dorset. All of the following shots were taken at an aperture of F2.8 in auto exposure mode, using my Zuiko Olympus OM 90mm F2 macro lens on the same roll of film, Kodak E100G positive. I hope you will be able to see the tone of the picture changing with the change in the exposure compensation.

1st shot. Regular auto exposure.