Playing with a New/Rental Lens: Simga 70-200 f2.8

Let me start by giving a little background. As I have previously posted I recently shot a concert for a friend of mine. One of the "lacks" in my lens line up for that gig was a long focal length lens that was Auto Focus. discussing the shoot with Jason later on, we decided to have me shoot another concert with a longer lens and focusing more on the band members and for tighter head shots. So I made a reservation with www.cameralensrentals.com and waited for it's arrival. Once it got here I spent a little time outside playing with it, and also another morning on my way to work. I really wish I would have had more time to spend with it getting to know it's quirks. I'm not sure that I would buy this instead of the Sigma 100-300 f4 I want to buy, but I wouldn't mind owning it either.

The lens itself is very solidly built (As you would expect from Sigma's EX or "ProGrade" line of lenses) and is a good sized lens for carrying around. Not too big, but not so small it feels like a toy, on my K200d with Battery Grip attached it looks like a serious piece of glass. Interestingly the zoom ring turns opposite of my Sigma 17-70 f2.8-4.5, I'm not sure why a manufacturer wouldn't be consistent with that, but I can live with it, though it is irksome. My real nitpick is that f2.8 is not particularly sharp, and in fact is downright not quite useable for me. Now this could be the fault of technique, I was shooting handheld, and or back/front focusing issues etc... I just figure that in broad daylight I should be able to get a sharp shot at shutterspeeds more than twice the focal length of the lens... sigh.... It does perk up at F3.5, and gets quite good at F4, but the 100-300 is supposed to be stellar wide open at F4.... Anyway, I really enjoyed this lens, and here are a few shots.

This is at the closest focus distance, handheld, 200mm.

F2.8

F4
F4 Re-Focused
F5.6
F8
F11
F2.8
F3.5
F4
F4 Auto Focus snared the husk on the front left.
F4 Hand Focused on the flower in the middle.
F5.6, 1/800" ISO 400, Cropped and Cleaned up with NeatImage
F4, 1/1000" ISO 400, 200mm
F4, 1/1600, ISO 400, 93mm
F4, 1/2000", ISO 400, 70mm
F8, 20s, ISO 100, tripod with Cable Release.