Under exposing in Raw
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21-08-11, 09:25 AM
Join Date: Sep 2009
Originally Posted by
Hi Gang, just reading Andydo's thread about his under exposed Wedding shot. I use a Canon 450D and usually shoot in Raw. I was advised to deliberately underexpose in Raw to give me a faster shutter speed. The reason given was that it's dead easy to tweak it in Camera Raw or Lightroom 3 to bring out all the detail. Was this good advice or am I losing something by not getting it right in camera?
You've had some great advice from those better qualified than I, but one point that hasn't been raised is what mode you're shooting in and what settings you've used to underexpose an image. I had a Canon 400D, and now own a 550D. I can't remember for sure if all the variables listed below applied to the 400D, but from memory they did in the main, and so will be the same for the 450D.
If you were in P (program) mode, exposure compensation will affect both shutter speed and aperture value.
If you were in AV (Aperture Value) mode, exposure compensation will affect shutter speed but not change the aperture value.
If you were in TV (Time Value) mode, exposure compensation will affect the aperture value but not the shutter speed.
If you were in M (Manual) mode, by default, exposure compensation will affect shutter speed and not aperture value.
In addition, if you set the ISO manually it will remain the same value. However, if you set ISO to Auto, the ISO will change to maintain the correct exposure up to the point where Auto ISO limits are set. Beyond that it will change either aperture or shutter value, dependant on the rules above.
So if it's shutter speed you are trying to maintain, make sure your camera is set to TV mode when invoking exposure compensation.
I can't account for how other manufacturors design their camera bodies for these methods of exposure compensation, although I imagine it would be the same.
Last edited by rbarry; 21-08-11 at
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