I have a Nikon D80 and a SB-400 flash. I have been perfectly happy with both -- until last month: when I use the (external) flash, it would fire alright, but the picture is dark, i. e. I suspect the flash fires either too early or too late. Oh, and that happens with fresh batteries as well. I would like to figure out whether it's the camera or the flash that's the problem. So far, I haven't had any problems with the built-in flash(let). Can anyone help me troubleshoot? Is my camera the problem (= expensive) or is it the flash (= relatively cheap)?