[jro]

I use a K100D to shoot indoor concerts in venues with horrible lighting. I've found that I miss a bunch of shots due to either my own failure to properly manual focus, or the auto-focus locking on to something not quite where I want. For example, the AF will lock on to a microphone stand in front of the performer rather than the performer, but the performer looks in focus on the viewfinder and I don't want to miss a shot, so I shoot. I've adjusted both the camera settings and my technique to try and account for this with some degree of success, but I'm wondering what more can be done.

So, does anyone have suggestions for improving my percentage of properly focused shots? I've heard tell of some accessories that might help, like the magnifying eyecup, but with that I'm worried about the vignetting. I've also seen people mention replacement focusing screens like the Katz Eye, but I can't really tell if these would help my particular situation.