There is a feature on most all DSLR cameras that not many people know about or understand how to use. That is the exposure compensation button. What exactly is the Exposure Compensation Button? Well way back in the dark ages of film photography people would shoot pictures at the beach or in the wintertime with snow on the ground when the sun was out and the pictures would be underexposed. Which means their prints would look dark. Or they’d be shooting a white subject like a white dress surrounded by dark things in sunlight which would cause the subject to be overexposed or the white dress to be blown totally out with the highlights. What was the reason for this? Most of the meters back then were center weighted average meters. There was no 3D Matrix metering or ‘on-board’ memory that the meters could draw from to help out with the scenes. These meters were basic light meters that measured the light being reflected into the lens.
Professionals knew how to read these types of scenes and adjust their setting because of their experience, so for them this wasn’t a problem. But knowing this was a problem for the average consumer and weekend photographers (these people spend the most money on cameras and equipment), camera manufacturers created a way for them to adjust or set the meters for scenes such as this and that was the Exposure Compensation button. The exposure compensation button basically lowers or raises the value that the meter records. That is pretty simple in practical terms.
Where is the exposure compensation button? Here is where I tell you to get out your cameras manual and look it up. On my Nikons it is on the top of the camera. It is a button that has a square with a ‘+/- ‘symbol on it. I hold it down and turn one of the dials to adjust it. It can be set anywhere from -5 to +5 in increments of 1/3 EV (Exposure Value).
In a nutshell this button works just like you would think it would by the symbols. If you want to darken your images you put it in the minus range, and if you want to brighten your images you put it in the plus range.
Now if you want to understand it completely here is what it is doing. When you put the Exposure Compensation in the minus range you are adjusting the cameras meter to meter the light anywhere from 1/3 of a stop to 5 stops darker which in turn will make your settings faster (i.e. the shutter speed will go up, and/or the aperture will decrease. Which means the f/numbers will go higher) to allow less light to hit the sensor of the camera. And just the opposite is true if you go into the plus range. Your settings will get slower (i.e. the shutter speed will slow down and the aperture will open up. Which means the f/numbers will get smaller) to allow more light to hit the cameras sensor.
Once I make an adjustment with the Exposure Compensation there will be a symbol displayed both in the viewfinder and on the top of the camera to let me know I have it set (Check your manual to see what symbol is used for your camera). Okay right, like I really noticed that when I was first learning how to use this button. Seriously, that was my biggest frustration with this button when I first started to use it, I would forget I set it and when I shot some pictures of different scene afterwards the images were improperly exposed. I banged my head until I remembered I had set the Exposure Comp button- DOH, operator error.
Now I had told you that this button was created way back when meters were really basic before the Digital Era of photography, so why is it still there with the sophisticated cameras we have now with all of the wonderful computerized metering? Because camera meters, even the computerized ones of today don’t know what it is you’re taking a picture of or how you want that picture to look. These “High Tech” meters still get fooled by difficult lighting situations. And there is another reason to use it.
I use the Exposure Compensation button ALL the time, especially when I am shooting in the daylight. My Nikons overexpose by 1/3 of a stop to 2/3 of a stop. I do not know why the meters do this, but I know this to be true because I tested them against a dedicated light meter to verify their accuracy. The light meter won. So I always leave my Exposure Compensation button set to at least -0.3 to -0.7, which is 1/3 of a stop to 2/3 of a stop less exposure. So now I can shoot with confidence that my highlights aren’t going to be blown out in most situations and that I have richer blacks in my images.
Now I am sure you are going to ask, would you need to use the Exposure Compensation button even shooting in manual? Yes. Remember, even in manual you are using the cameras meter to meter your scenes the same way the camera is using the meter to determine the settings when you have it in a program mode.
There you have it. You can test this out yourself and see the results.