Sigma 170-500 mm f/5-6.3 Aspherical RF APO Lens

A great tele with crystal sharp image and beautiful color, if the subject is not moving. Basically this is a poor man's tele that happens to have great optics, yes, the optics is fantastic, but not much else.

AF is slow, tracking a flying bird is impossible for me. Manual focus ring is added as an afterthought for sure, it's loose with very limited travel, so not very useful at all. The lens creeks a lot if not careful. I bought a custom lens cap so I can actually close and open the cap when the hood is on. It's quite heavy. So tripod is very useful if not a must for this lens. The tripod collar is great though - smooth, secure and solid. Shooting slow moving or stationary animals in the zoo is perhaps the best use of this lens for me. The AF is quite accurate if you allow it to work its way through it.

Great optics - sharp even wide open, great color and contrast. Flair and AC are not bad to be noticed. Good tripod collar.

Lens cap is a joke. Lens creeks terribly. AF not good for moving tracking, MF not accurate. Heavy (not the lens fault for sure, but still, it's heavy) To me a 1.5lb lens is not heavy, but 3 pounder is.

None. This lens is perhaps the cheapest 500mm tele out there today. With the Mark II out with HSM, this lens is even cheaper today, which makes this a great buy if you are not shooting flying birds. I tried the birds a couple times and give up - AF is just impossible - with 350D and 40D and 5D. AF Canon 70-200 USM is instant, on the other hand. But at 200mm, it's way too short.

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