Well I finally bought a Sigma 100-300f4, and while I haven't taken that many shots, it's living up to it's reputation as a very good lens.
It's focusing speed is nice and snappy, pretty much on par with it's little brother the 70-200 2.8, nice and sharp wide open, which is great because I sold my 4mth old 100-400 canon as I wanted something faster, but couldn't really afford anything in the 2.8 range, and while I could've paid a bit more and got the 300f4 canon, I really wanted the convenience of a zoom, and it would've been pointless if I'd have to open up a stop to get sharp images, might as well have kept the canon.
Anyway here's a couple of shots.

F4

Sigma 100-300f4 test shots f4 by dulvariprestige, on Flickr

F8

Sigma 100-300f4 test shots f8 by dulvariprestige, on Flickr

F4 100% crop

Sigma 100-300f4 test shots f4 100% crop by dulvariprestige, on Flickr

F8 100% crop

Sigma 100-300f4 test shots f8 100% crop by dulvariprestige, on Flickr



IMG_7877 by dulvariprestige, on Flickr


IMG_8057 by dulvariprestige, on Flickr