Yo, Photographers: Camera Autoexposure Prob...

Canon G11. When set on autoexposure, the camera initially seems to adjust properly, then gets too dark. Pictures are drastically underexposed. On manual exposure settings, no problem. Reset all settings to factory defaults. No help. Everything seems clean on the outside. What’s up?

What’s the likely problem, and is it fixable? Can I do this? Online help for camera repair was frustratingly sparse. Any websites I might’ve missed or good books I could try?

Can you post sample images with EXIF intact?

I’m not entirely sure what I’m expecting to find, though. If you really did reset all settings to factory (so you don’t accidentally have some exposure compensation mode on), I can’t see why you would be having that issue. But post away anyway, just in case there’s something that looks interesting in the metadata. ETA: (I guess on the G11, it’s an actual dial on the left side, not a software setting. Make sure that is set to “0” and not “-2” or something.)

If you know how to look at the EXIF data that’ll probably point to the problem. Three things can cause it to under expose, the shutter is speeding up, the aperture is stopping down or the ISO number is lowering.
It could be as simple as you bumping something on the camera or it could be something malfunctioning, but checking the EXIF data is going to be the place to start.

Also, what happens if you point the camera at something, leave all externals the same (same lighting, same distance to the focal point, same everything) and just start snapping picture after picture?

Lastly, and I know this would result in overexposed pictures as well, but make sure you’re not accidentally turning on bracketing.

And also, are you sure your camera is actually able to properly expose for the scene (meaning there’s enough light to begin with)?

In dark environments, non-SLR cameras will temporarily and drastically ramp up the exposure or ISO in order to see just enough of the scene to focus and meter with, and then put it back to what it thinks is the actual, correct setting. You’ll see this as a sudden brightening and then darkening of the screen.

If you have your camera’s max shutter speed and/or ISO is artificially limited – and some will come like that default from the factory because setting them too high can negatively affect image quality – it may not be able to give you a bright enough shot because there’s just not enough light for your lens.