Which lens on which camera?

I wish to use two cameras for a conference. The key captures (still) would be a close-up of the speakers and the

overall shots of the participants (about 200) in a hall under available lights, most probably using ISO1600. I

will be using Canon 7D and 5Dll with Canon 70-200mm f2.8L IS ll and Tamron 24-70mm f2.8 VC. Which lens on which

camera would give better results?

The reason for seeking help is that I have no opportunity to experiment and it would be rather awkward to keep

changing the lenses at the location.

www.husain2.webspace.virginmedia.com

<p>Hard to say, Husain, without knowing how close you'll be to your subjects - that'll indicate whether reach or width will be most important.</p>

<p>The 70-200 on the 7D will give you the reach if needed and the 24-70 on the 5D will go quite wide - but there will be a gap in the middle. Reverse the choices and you won't have that much reach and won't be able to go real wide - and have an overlap in the middle - only you can make that choice based on the location.</p>

<p>When using dual formats like this, I usually put the wider lens on the full frame camera, since it provides a significantly larger overall angle-of-view coverage.</p>

<p>To do the math: With 24-70 on 7D and 70-200 on 5D2, you'll have effective field-of-view coverage range from around 40mm to 200mm in full frame terms.</p>

<p>With lenses on opposite cameras you get 24mm to 320mm in full frame terms. A much wider range.</p>

<p>Keith's answer is the only right one to this question. There is more than just focal length and camera body to the equation. Distance is critical. </p>

<p>I would agree with Keith, but then again, intuitively I would go with 24-70 on 5D2 and 70-200 on 5D2. Your intended goals seem to indicate that this would serve you well, for wide angle shots of the attendees and tight headshots of the speakers.</p>

<p>I would not worry at all about the gap that has been mentioned...no one said you couldn't swap the lenses as required, on the day. You effectively have gapless coverage from 24mm to 320mm with f/2.8 glass. Pretty decent.</p>

<p>Also, both bodies have pretty good high ISO performance. I would not hesitate to push either of them to ISO 2500 or even 3200 in a pinch...</p>