I never fully tested my VRI lens, but during my test photos with the Sigma OS, I was handholding images at 1/15 and they were still as sharp as at 1/60 from what I can tell. I start to notice the drop off occuring at around 1/13 - 1/10. When I'm out and about, I don't like to handhold below 1/50th so I was quite surprised by this, and might have to rethink what shots I can do without having to bust out my tripod.
As far as trying to photograph the furry subjects around my house, it was really cloudy day which makes the lighting at my place worse. I could easily tell the difference between the Nikkor and the Sigma in a couple areas right off the bat.
First, the barreling at 17mm on the Sigma is really noticeable. I remember a few shots with the Nikkor I took at 18mm and later saw it in processing, but with the Sigma you can see it thru the viewfinder easily. It goes away around 22-24mm.
Second thing I noticed was the better speed. A 3.5-5.6 is not conducive to taking shots in my apartment when I rely on natural light from windows and very little else, so the 2.8 makes a big difference. But even the shots at f/4+ seemed a lot brighter. Which goes along with how my other two Sigma lenses react with the D80 body. All of them are about 2/3 of a stop brighter than what the light meter is telling me. Couple that with how well the OS was working, it makes me feel good about my purchase.
From all the test shots I took, this was my wife's favorite. I had to take it upside down, and I haven't decided if the 90deg or 180deg rotation is better.
Archibald stretching and yawning.
