Here’s some really basic (and quite import­ant) info that’ll help you take bet­ter pic­tures, trust me. It’s a long post, but worth your while read­ing it (at least I hope).

Ever wondered what the little +/​-​but­ton (or menu entry) on your cam­era does? It when you access it your cam­era will usu­ally dis­play a scale like so: [ -2 … -1 … 0 … +1 … +2 EV ] and might men­tion some­thing along the lines of expos­ure com­pens­a­tion or adjust­ment.

Well this func­tion­al­ity is quite an import­ant one and worth­while under­stand­ing. Let me start by (loosely) explain­ing how your cam­era determ­ines how to set the expos­ure in the first place (that is, how much light it’ll have to cap­ture so that the scene looks “cor­rectly” exposed, not too dark, not too bright, but “just right”). Sci­ence has shown that your aver­age, cor­rectly exposed pic­ture will have a cer­tain aver­age bright­ness of around some value x (on a cer­tain scale). In other words, if you cal­cu­late the aver­age bright­ness of each pixe in the image, you should get a value around that cer­tain value x. Hence, to get a “nor­mal” pic­ture, your cam­era adjusts aper­ture, shut­ter speed and ISO so that the res­ult­ing image will have an aver­age bright­ness of x. Got that? Right.

Here’s a prob­lem: not every situ­ation you will pho­to­graph will be “aver­age”. Two extreme examples would be 1) a white bunny sit­ting in the snow — a pic­ture where your aver­age pixel will be much brigther than “nor­mal” — or 2) an actor dressed in black on a theatre stage with a black back­drop — here the aver­age pixel bright­ness will clearly be darker than nor­mal. Well in both cases, your cam­era doesn’t know that it’s look­ing at “extreme” scenes and thus will try to do what it always does: expose such that the aver­age pixel bright­ness will be x. The res­ult: bunny and snow will be grey, instead of white — and the theatre back­ground will be grey, instead of black.

The solu­tion: In those extreme cases, you tell the cam­era that it’s con­fron­ted with an extreme situ­ation, that is a scene that is either brighter or darker than aver­age. And, you guess right … this is what the expos­ure com­pens­a­tion func­tion is for: Neg­at­ive val­ues on that scale tell the cam­era the scene is darker, and pos­it­ive val­ues stand for brighter than aver­age. Easy enough, right?

Here are some more situ­ation where you might want to try using this adjust­ment: Even­ing scenes and sun­sets (set neg­at­ive val­ues), bright days and sum­mer beaches (try a pos­it­ive value). The photo above was taken late-​ish in the even­ing. Without any com­pens­a­tion the pic­ture taken by the cam­era was way to bright, the sky was almost white and it looked like it was taken in the middle of the day. But with a –2 EV com­pens­a­tion the pic­ture then reflec­ted much more what the world looked like when I was there.