Thoughts on the 5D mark II
Two weeks ago I did my first concert with my new 5D markII (Lenny Kravitz, no less). I'm quite happy with the results. In fact I've never, ever brought so many good shots from a concert. By "good" I mean "exploitable" : low noise, correct exposition and focus. A quick statistical check on a few of my previous concerts yields an average ratio of 30% of keepers/taken. In this concert, the ratio was 54%.
I'll spare the praise on its high-ISO performance. Everything you've already read is true, yes you can shoot at 3200 and get something exploitable. Noise becomes noticeable at 800, under that it's irrelevant. But the other huge improvement compared to the 40D is a working auto-ISO mode. This allowed me to take shots at 100 ISO. In concert. I'd never have thought that possible, but I have a bunch of perfectly sharp shots taken at well below 800, which is usually the lowest setting I use in concert (sometimes 400 when there's really a lot of light). The other good part of this mode is that, well, it varies ISO. Which means I have both noiseless, clear shots and fairly grainy ones when it kicked into 3200, and this lets me vary the mood at post processing. From
In conclusion : can't wait for the next concert :-)