Recently I've been shooting in really low light conditions..it's akin to shooting crowd in a concert with only stage lights illuminating the faces..whilst shooting f2.8 at ISO3200 giving 1/25s can give good images..that's not my concern here..shooting in such conditions is never easy and I'm pretty happy with the images that I can capture..
My real concern is the AF when shooting in such conditions..it's very slow to lock on..I'm using the Sigma 17-50 f2.8 HSM on Canon 50D..let's just say I cannot use the flash and thus AF beam assist is out of the question..without much contrast to focus on..the lens AF is having a hard time finding a lock..sometimes it takes almost 3-5 secs to get focused..
I've known that Sigma lens are not well-known for their low light AF performance..but it can't be that bad right? I'm starting to think if my 50D could be the cuplrit..it is a 3yrs+ old body no matter what..or could it be that the 2 is not a good combo(though this will be very far fetched!)? Or I just have to accept that this is always gonna be a problem shooting in low light and I should just live with it?