The simple version, is the f-stop is lens focal length divided by aperture diameter.

Even that makes my brain hurt.

I do a fair amount of portraiture, candids and action, so speed is of the essence--when shooting film I'd happily go up to 1600 in black and white. Even sometimes for architecture too.

Because you can barely take pictures anywhere with those speeds! Or with any zoom lenses...

So totally not true! When I used to shoot on film I used tons of 64 and 100 speed film. It's amazing outdoors. I've also done great work with those speed films and a good flash setup. You do have to use higher quality telephoto lenses with slower speed film, and true telephoto and not zoom lenses are also much better with show speed film.

Oooh, this is a timely discussion for me. I lost my camera this weekend, so I'm looking for a new one. It was a Panasonic Lumix DMC-TZ3 which had some good features, but lacked in others. The thing I liked least about it was that it was difficult to take good pictures in low light. For example, I could either take this without a flash, which is grainy and blurry, or this with a flash, which washes out all the stage lights. Compare those to, say this photo, taken by someone else with a Nikon D80.

Are there cameras that will take low light photos near the quality of the D80, but that will fit in my pocket like my Panasonic did (its dimensions are 4.1 x 1.4 x 2.3 inches)?

Given that I'm still on a Pentax K1000 I think we can safely assume speed is not of the essence for me! My only complaint is manually focusing; I hate that.

I do a fair amount of portraiture, candids and action, so speed is of the essence

Huh, I used to shoot indoor theatrical shots with 800 speed film. Very low light. I'd have to be careful to have a stable shooting platform, but I always got lots of very good shots. Certainly not every shot, but that's why I'd always shoot lots of coverage.

dcp had a TZ-3 at the F2F. He was complaining about the poor low-light performance, too.

Are there cameras that will take low light photos near the quality of the D80, but that will fit in my pocket like my Panasonic did

I tried to find some and never really did. I had to move up to the Rebel XTi for really good low light stuff.

The simple version, is the f-stop is lens focal length divided by aperture diameter.

Even that makes my brain hurt.

sits next to Megan, hands her the open bottle of aspirin.

I need to get a good tripod. I really like taking shots in dim natural lighting conditions, but especially with my digital camera, most of my shots are useless because I just can't hold still enough.