Sigma 100-300mm f/4 EX DG IF HSM Reviews

After using this lens for over a month, I am very pleased with the performance. I typically use it with the Sigma 1.4X Teleconverter. The sharpness, contrast, and color of the photos are as good as any of my other lenses including the primes.

It is large and heavy so it does not tend to travel with me on longer hikes. Carrying the camera for any length of time with the lens mounted is not practical for me because of the weight. But when a great clear image of a distant subject is needed, the lens comes through.

This lens is just impressive, not only because it is a zoom lens. Its resolution is excellent. The only drawback on my camera (EOS 5D) was that AF was not alway reliable. But the potential of this lens (ie when focused on spot) is close to many primes.
The main directly visible difference in terms of resolution compared to good primes (e.g., the Canon 4/300) is a more pronouced resolution fall-off towards the edge/corner.

I love the build and handling of this lens. Some folks take about how heavy it is but still I find it is relatively easy to handhold.
IQ is exceptional! Even at F4, which I use quite often, it doesn't disappoint. I like the versatility of the zoom also. Makes life much easier and without the compromises.

This lens rivals my Canon 100-400 L 4.5-5.6 IS in photo quality--it's quite impressive! With it's constant faster aperature it is only slightly handicapped by comparison to the IS, as it will produce good photos wide open. It performs quite well with a 1.4x extender--much better than I would have expected.

Compared to the Canon it's AF is slower. It is usable for birds in flight, but you do need to track them a bit to get focus. The Canon is instantaneous.

AF, especially in dim light, is not reliable. And it does not always focus well in good light on things like black bears to the extent that is completely blows some nice shots. The Canon never fails.

I need to send the lens for repair as something with the focus ring is loose. This problem was documented on the Web by others.

Overall, this was a heck of a bargain when I bought it years ago (2003?) as it was half the cost of the Canon. Last time I checked the prices were growing closer. If you require reliable AF in dim light or if you shoot a lot of birds in flight look elsewhere. Otherwise its optics are very good.