Concert (low light) focus-recompose problems?

[gordholio]

Hi everyone:

So I took my T2i, 85mm 1.8, and 50mm 1.8 (nifty fifty) to a small local concert last night (no flashes allowed, of course). I was maybe 30-40 feet from the solo performer. Shutter speeds were in the 1/250 to 1/400 range. Aperture was generally between 2.0 and 3.5. ISO was 800. AF selection was manual, center spot.

I have one huge problem. Lack of sharpness. I took the pics by focusing on her face, keeping the shutter button halfway depressed, recomposing (lowering) the shot to frame her the way I wanted to see the pic, and then taking the shot. Inevitably, the head stock of her guitar was in better focus than her face in most pics. Grr.

I'm enclosing two pics - one is the original full-stage shot and the other is the same pic cropped to show just her torso and guitar. I wish you could all see the high-res versions.

I've read some things about the potential problems associated with focusing and recomposing. Or maybe there's something else that I'm too stupid to remember. What do you all think? Maybe the shutter speed needed to be faster, though her hands were moving pretty quickly and they seem to be no less sharp than anything else - with the exception of the guitar head stock, which looks, to me, to be sharp. I dunno - maybe I'm pixel peeping. though I do know that I'm new to indoor pics such as this and probably need more experience.

I don't think it's either of the the lenses front or back focusing, because the problems were evident with both lenses. Also, I've taken pics with both lenses in daylight recently, and both are capable of delivering sharp images. But that's in the daytime - don't know if that makes a difference.

I'm kicking myself for not using one of the other focus points. Don't know what I was thinking. Still, it would be nice to have a few opinions as to why I experienced this problem. Thanks in advance to anyone who replies.

[Yusef]

You can't expect to get the sharpest pictures in low ambient light. You'll need a serious boost in light to get the sharpest pictures. That being said the sharpness in the shot isn't bad considering the conditions.

[BigAlz1]

Those look good for 1.8 on either of those two lenses. You have to keep in mind that higher ISO and shooting wide open will not give you "sharp" images; however I think they look fine.

If that is the style of shooting you will be doing and you're not 100% happy with your results then you will need to get faster glass. I have seen some phenomenal pictures come from the 85mm 1.2 at low light with very little ISO.

I have personally owned both of those lenses and they both gave me very soft pictures wide open.
With glass that fast and that camera, you should have been able to use auto focus and just selected your AF points as needed. Also if you were shooting at 1/250 to 1/400 then you could have played around with the shutter/ISO/AV ratio a bit more. Shutter speeds of 1/125 with ISO 400 would have been better then 1/250 ISO 800 or go up on your AV for a flatter, sharper image.

Next time, make a point of trying more combinations while keeping proper exposure. I personally chose the AV I want then go for the lowest ISO I can get away with. It almost sounds like you were just trying to keep a fast shutter speed and that will cause poor PQ in most low light situations. I have got away, in a very dim lit bar before, never getting above 1/60 - 1/125 shutter speeds and had great turnouts. However I had to shoot wide open and that too will give you less than perfect PQ at times.