I do most of our Parish photography and I just upgraded my 7D to a 5D3 which I absolutely do not regret. I have a 70-200 F4 which has been unusable with no flash in church shooting. I have rented glass some with my 7D but got an 85 1.8 last year which works OK. This was with my 7D, 85mm, f1.8, 1/250 at ISO 2000:
My 85mm has really improved my photography but when I can get enough light I like the IQ of my poor man's 70-200 f4 better. I'll need to go to the F4 IS or the 2.8 non-IS.
2.8 IS isn't going to happen.
That's why I'm directing this to wedding shooters: this is a pretty low light church, and I'd like to your comfort zone for the limits of a 5D3.
1. What maximum ISO are you comfortable with using 5D3 for nice IQ?
2. How slow would you feel comfortable shooting the F4 IS at 200mm..... can you do 1/60th?
3. If you guys and ladies are comfortable shooting at 6400 ISO, wouldn't that imply that I should consider the F2.8 non ISO (I'm pretty sure I could pull off F2.8, 1/250 sec, 6400 ISO)?
I know 3 out of 4 people like the F4 IS lens over the 2.8, but with the 5D3's high ISO capability I'm wondering if the 2.8 might have some advantages (nicer bokeh, less expensive lens). I'm not worried about size or weight.
Thanks for your help!