Is it common to for the 40d to underexpose everything by 1 stop? I can correct it on the camera by adding a stop of via ev, but I am just curious if this is a common issue.
Depends what you're shooting and what AE mode you're using.
The AE system can get thrown off by large expanses of light colors like snow, water, white-rock-cliffs, etc, and underexpose them by a stop or two. Other things like portraits and mixed landscapes often come out right on the money. A small white bird in a dark tree will come out overexposed every time. The moon will often come out overexposed unless you really know what you're doing. Like I say, it depends. Of course, none of that is unique to the 40D. I believe most DSLRs behave like that.
Most cameras will require some exposure compensation - especially under artificial light. You just need to learn the quirks. For example, with my Olympus DSLR I tend to keep the exposure at default under cloudy conditions, at -.3 to -.7 in sunny conditions and +.3 to +.7 under artificial light. AE sensors try to get it right in all settings, it just doesn't usually happen. My brother has a 40D and he keeps his around +.7 most of the time.
The Canon 40D has a slightly different tone curve compared to the Canon 20D/30D series and it does make the middle tones output look a bit under in many cases. It is presumed that this is intentional to protect highlights at default settings while keeping highlight and middle tone relationships.
If you are comfortable using the EV compensation and understand how the histogram and "blinkies" work on your camera then feel free to compensate, with the usual caveats about exposing to the right without overexposure.
Do check your work using software that has a competent histogram so that you can corroborate the camera's histogram until you are sure of the results.
The Canon 40D has a slightly different tone curve compared to the Canon 20D/30D series and it does make the middle tones output look a bit under in many cases. It is presumed that this is intentional to protect highlights at default settings while keeping highlight and middle tone relationships.
If you are comfortable using the EV compensation and understand how the histogram and "blinkies" work on your camera then feel free to compensate, with the usual caveats about exposing to the right without overexposure.
Do check your work using software that has a competent histogram so that you can corroborate the camera's histogram until you are sure of the results.
what i have noticed is that it main underexposes indoor photos when the light is not very good. If i crank up the ev to +.7ish the histogram is looks pretty good and the pictures turn out well exposed. I took my camera outside just to check on things and it exposed everything under somewhat overcast skies pretty well without an compensation. So, thanks everyone for the tips.
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The AE system can get thrown off by large expanses of light colors like snow, water, white-rock-cliffs, etc, and underexpose them by a stop or two. Other things like portraits and mixed landscapes often come out right on the money. A small white bird in a dark tree will come out overexposed every time. The moon will often come out overexposed unless you really know what you're doing. Like I say, it depends. Of course, none of that is unique to the 40D. I believe most DSLRs behave like that.
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If you are comfortable using the EV compensation and understand how the histogram and "blinkies" work on your camera then feel free to compensate, with the usual caveats about exposing to the right without overexposure.
Do check your work using software that has a competent histogram so that you can corroborate the camera's histogram until you are sure of the results.
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what i have noticed is that it main underexposes indoor photos when the light is not very good. If i crank up the ev to +.7ish the histogram is looks pretty good and the pictures turn out well exposed. I took my camera outside just to check on things and it exposed everything under somewhat overcast skies pretty well without an compensation. So, thanks everyone for the tips.