Summary: I have owned the Canon 100-400L and though I know it intimately from shooting many images through it and having to do field repairs, I just never fell in love with it. I think for me the push-pull zoom was just too awkward. Others love it, not me.
Great telephoto Lense for wildlife, but a bit soft
28 July 2011
Summary: I originally purchase this lense for my African Safari trip in early 2012. I used it with my Canon Rebel T3i or 600D together with 3rd party battery grip. I've now used it multiple times at Africa, Montana and Galapagos. The zoom was sufficient and the lense is sufficiently fast.
Summary: I've compared the Sigma 120-400mm lens, and at the same time, also the Canon 100-400mm L lens (priced at $1600). I took both lenses,on a tripod, and shot numerous photos with both from the same position, different focal lengths, and on the same subjects.
Summary: I had read mixed reviews on this lens and wasn't sure if it would be the best choice for my needs. I do mostly wildlife photography and needed a long reach lens. After driving myself crazy, I finally chose to buy it over the more expensive Canon 100-400 IS. I was amazed for so many reasons.
Summary: This is one big hunk o' lens (5 lbs) that benefits greatly from the use of a sturdy tripod and a remote shuter release. The photos I took were acceptably sharp on a tripod, but it takes a steady hand, even with the OS, to get similar results hand-held.
Signma 120-400mm with Pentax K3 moving subject focusing
Richard Albeck, Amazon
28 July 2011
Summary: It's a heavy lens. Not so much that I worry about it. But for extended use you would want a monopod at least if using higher magnifications. I have been testing with the continuous focus with Pentax K3 and it works well. Focus is nearly silent and pretty quick.
Summary: This is my go to Zoom lens. I use it with the 1.4 tele conv. One thing, It's a Hog for it's range. If you really want to see photos taken with this lens you can see my photos at photoshop.com (callofthewild) Most are taken with this lens. 4 out of 5 due to size and focus issues.