I am not clear when you would adjust exposure compensation versus changing ISO, shuutter speed or aperture. There are many ways to adjust exposure but when to use one verus the other is confusing me. Would appraciate any insight.
JosephK Seattle, WA, US Nikonian since 17th Apr 2006
Wed 27-Jun-12 04:30 PM
#1. "RE: D5100 exposure compensation" In response to Reply # 0 Wed 27-Jun-12 04:33 PM by JosephK
The combination of ISO and shutter speed and aperture gives you an exposure value. Changing the ISO or shutter speed or aperture results in one of the others changing in the opposite direction to maintain the same exposure value. For example, if you double the ISO you then half the shutter speed to maintain the exposure value.
You change the exposure compensation when you don't like the exposure value picked by the camera. For example, the camera meter may be confused by all the snow around your skier friends and underexpose the scene because the camera does not know that all that snow is supposed to be white, not middle gray. You then might need to add some +EV to let in more light to get the snow back to white and your friends not underexposed.
There are two ways to change your EV compensation. In manual mode, you just change one of the exposure settings (shutter, aperture, ISO) -- handy for just a few pictures. Is any of the auto modes, you set the EV value to a +/- value and the camera does the calculations -- handy for many shots.
---------+---------+---------+---------+ Joseph K Seattle, WA, USA
#2. "RE: D5100 exposure compensation" In response to Reply # 1
Thanks for the reply. I mainly shoot in aperture priority mode so I would use the aperture to change my exposure. It sounds like the exposure compensation is mainly used for the auto modes. I think that answers my question!
#3. "RE: D5100 exposure compensation" In response to Reply # 2
Welcome to Nikonians! Aperture priority mode is an "Auto Mode". Here are two examples where Exposure Compensation is used to adjust for ambient conditions. When you subject is on a stage with black curtains in the background the matrix meter can easily be fooled into over exposing your subject because of the dark background. Dialing in some negative exposure compensation will skew the meter to increase the shutter speed (in A exposure mode) resulting in your subject being correctly exposed.
With back lighted white curtains in the background the matrix meter will be fooled into under exposing your subject. Adding some positive exposure compensation will skew the meter to use a slower shutter speed (again in A exposure mode) to adjust for the under exposure, resulting in your subject being correctly exposed.
When the foreground or background is significantly brighter or darker than your subject and you are using P, S, or A exposure modes, using Exposure Compensation allows you to compensate or adjust the exposure to fit the condition. Good Luck and Enjoy your Nikons!
#5. "RE: D5100 exposure compensation" In response to Reply # 3
Thank you. For the scenario you described, I would switch to spot metering instead of matrix so I would expose based on my subject and not background. But I am still learning so I will try exposure compensation and compare results.
I do understand how ISO, Aperture and shutter speed relate to each other. And I get how exposure compensation works. I think I am still searching for a good use case to apply it. One thing for sure, it is nice to have options!
#7. "RE: D5100 exposure compensation" In response to Reply # 5 Thu 28-Jun-12 11:01 PM by coolmom42
I find exposure compensation useful if there is a specific part of the image that I'm concerned about overexposing or underexposing.
For instance, I might do spot metering on a darker-colored flower but be concerned that a light section of foliage will be blown out. But if I meter off the lightest foliage, the flower (my main subject) will be grossly underexposed. So I meter off the flower, deliberately underexpose the entire image a little, to avoid blowing out the foliage. The result is a slightly underexposed flower that can often be corrected in post-processing, with detail preserved in the light section of foliage.
By the same token you can slightly overexpose the entire image to bring out detail in a black area or deep shadow that might otherwise be lost.
Exposure compensation can help you get the entire dynamic range of the image inside the camera gamut.
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#4. "RE: D5100 exposure compensation" In response to Reply # 0
When using Aperture Priority mode and you change the aperture, the shutter speed must change to keep the same exposure (keeping ISO constant in this case). For example, if f/8 and 1/125th gives you the correct exposure and you change to f/11, then the shutter speed will be 1/60th to give you the same (correct) exposure. When using Exposure Compensation, adding +1 will cause the camera to "overexposure" one stop from what the camera thought should be the "correct" exposure. For example, if f/8 and 1/125th is the "correct" exposure and you then select +1 Exp. Comp, the result will be f/8 and 1/60th.