In this video wildlife and nature photographer Steve Perry (from backcountrygallery) talks about what you need to know when it comes to exposure compensation.
What is exposure compensation and how does it work in different camera modes? in this video, Perry explains what you need to know about this topic. First, we need to understand that when exposure compensation is even relevant. Basically, if you are shooting in manual mode (that is manual exposure, not manual focus) than you are in control of all of the 3 exposure parameters – aperture, shutter, and ISO (if you put ISO on AUTO that means that you are not in “true” manual exposure mode and exposure compensation will be able to change your ISO).
In all other shooting modes (A/S/P etc.) changing the exposure compensation dial/setting will change one or more of the three parts of the exposure triangle (aperture/shutter/ISO), remember there is no forth “magical” exposure option that the exposure compensation can use – it will always change either the aperture (in shutter priority mode, the shutter speed in aperture priority mode and/or the ISO) that is it.
How does the camera decide what to change in every mode? that depends on the camera model/maker but in general, it will try and change the ISO as a last option and you have to remember that if for example, you set your camera to not go beyond ISO 1600 and you are shooting with an f/2.8 lens at f/2.8 and you are in low lighting conditions than pushing your exposure compensation might not help (you just reached the maximum that you can with the light and settings you have).
Perry also discusses in what conditions he would recommend using exposure compensation – these are basically times where the image might be too dark or too bright, making it difficult for your camera’s metering system to calculate the exposure correctly.
One of the reasons that we are not big fans of exposure compensation (aside from the fact that we mostly shoot in manual mode) is that there is a good likelihood that we will forget the exposure compensation on a different setting than zero which means that we might over or underexpose images unintentionally). You simply have to remember to change the exposure compensation dial/setting after you are done with it – if you are not sure that you can remember to do so – maybe it is better that you don’t use it in the first place.
We have looked at this subject in the past in a video by Tony Northrop which also covered spot metering which you can find here.