Inconsistent Exposure - Ideas?

[micstew]

Have a 10D and it seems the exposure is occasionally inconsistent. Even pictures taken in immediate sequence are sometimes exposed differently - some notably darker than others. Still looking for some sort of repeatable pattern but as of the moment the problem seems to occur at random. Anyone have this problem - or ideas to help solve it? Thanks much.

[Jon]

Examples? Environment you're shooting in? Exposure mode?

[scottbergerphoto]

Have a 10D and it seems the exposure is occasionally inconsistent. Even pictures taken in immediate sequence are sometimes exposed differently - some notably darker than others. Still looking for some sort of repeatable pattern but as of the moment the problem seems to occur at random. Anyone have this problem - or ideas to help solve it? Thanks much.If you are spot metering or partial metering, small movements in where the camera is pointed can result in big changes in exposure. The same thing can happen with backlit subjects.

[micstew]

Will post examples tonight (although they look pretty much like you would expect, one well lit and the next one not). Typically shooting indoors in less than optimal light, in either portrait or full auto mode. I definitely have some work to do to determine the specifics under which the problem occurs. In general, we are rather disappointed with the exposure on this camera - quite often needing to lighten pics in Photoshop. Blaming the tiny integrated flash, I have been considering a large boot mount flash but want to nail down this inconsistent exposure issue before spending any more money on this camera.

[Jon]

If you're shooting flash, is the flash fully recharged between shots? You'll commonly get a "Ready" indication before the flash is fully recharged.

[PacAce]

If you're using a flash, tat may very well explain the inconsistent exposures. When shooting with a flash try to be mindful of where set your AF points because that will affect how the picture is exposed. If the area under the AF point is very dark the picture will usually tend towards overexposure. If the area is very light, the reverse happens and tend to underexpose. Actually, it may seem like inconsistent behavior but it really isn't if you understand what's going on.

If you set the 10D to flash meter in center-weighted averaged mode, you'll probably get more "consistent" results but there's not switch you can set to select the cw avg. mode. One way is to set the lens on manual focus and the other is to link your focusing to the "*" button via the CFn-04 custom function.

[micstew]

Thanks all. I'll definitely be headed straight for the manual when I get home after Pac's input. Lots of user improvement to do before I can reasonably suspect camera failure.

[RodneyCyr]

I have seen a similar problem with erratic exposure with my Digital Rebel, yet I believe that I can eliminate all of the possible causes discussed in the earlier responses to the original post.

The camera nearly always underexposes the first picture I take after turning it on. If I retake the picture, the second one is correctly exposed. Yet the EXIF information is the same for both pictures, indicating that the camera "thought" it was using the same exposure for both.

I tried various tests to identify the problem: two different Canon lenses with similar apertures and focal lengths, under identical lighting conditions (cloudless sky), and five or six different times during the day. I tried both aperture-priority and manual exposure modes. I also tried with a freshly recharged battery, and cleaning the electrical contacts on both the lens and the camera.

In nearly every case the first picture was dark, but the second was normal. The results ranged from a nearly-black first picture to one that was only slightly dark.

In at least one case, the dark picture appeared to have greater depth of field than the normal one, suggesting that it was taken at a smaller aperture, although the EXIF information said it wasn't.

All of my tests were with the lenses wide open at f/4, and shutter speeds arount 1/1000 or 1/2000, at ISO 100.

Has anyone else seen this?

Have I overlooked anything?

[Jon]

Rodney:
If you're shooting flash, is the flash fully recharged between shots? You'll commonly get a "Ready" indication before the flash is fully recharged.

This can also occur when you first turn the camera on. It takes a while for the capacitor to get fully charged; the pre-flash may be successful, but there's insufficient juice for the "real" flash until it's been on a while.

[RodneyCyr]

Rodney:


This can also occur when you first turn the camera on. It takes a while for the capacitor to get fully charged; the pre-flash may be successful, but there's insufficient juice for the "real" flash until it's been on a while.


Thanks for the response, but I was not using flash.

I think I have a sticking shutter. The longer I leave the camera turned off, the worse the problem is, but only for the first exposure, and only for very high shutter speeds. Perhaps the first shutter curtain is not releasing on time, causing too-fast a shutter speed, or no exposure at all.

I repeated my test this morning after turning the camera off for about 12 hours. The first exposure was blank; the second was normal.