I am a bit baffled here. I own 60D with 50 1.8II and recently purchased EF-S 15-85. Also just got the Yongnuo 468II flash (no experience with it yet). Shooting at low light (tungsten, no flash) I've noticed that to get reasonable IQ I had to stop the 50mm to F/2 or even 2.8; While my 15-85 is 3.5-5.6 (3.5 only at 15mm if I remember right), it has an image stabilization which supposed to give me about three full stops more. So, while shooting at maximum F/5.6 with 15-85 IS on, it equals to F/2 if I use my 50mm (right?) and even faster with larger F-stops. Well...why do I need my 50 1.8 then when I can get the same images (or better) and use a zoom??? Ain't it supposed to be a low light lens?? Do I miss something here?
I ask this because I have to shoot low light event this Saturday (Flamenco dance). It will be a small event in a small, packed, dimly lit room. The stage will probably have some lighting from above but I doubt it will be enough. I will be close (very) to the stage and probably won't be able to use my newly purchased flash. I have a nice ball-head tripod (Sirui) but from my few recent experiences, it doesn't help a lot when the person you trying to shoot moving around. Having the (not so stellar) tools I have, how could I maximize the good/bad picture ratio (ISO, lens, tripod: yes or no)? Which lens is better to use with the flash (if I'd have the possibility)?
Sorry for the multiple questions. I've tried to shoot few low light events recently for my friends and was really disappointed with my results. This one is really important for me, don't want to @#@# it up again
As always, thank you for your time and advice!