Sigma 100-300mm f/4 EX DG IF HSM ...- User Rating: 
Summary for Sigma 100-300mm f/4 EX DG IF HSM ...- Sigma 100-300mm F4 - Great lens for the price.
Notes on Sigma 100-300mm f/4 EX DG IF HSM ...- I bought this lens because the Canon 100-400mm was alittle to much for my pocket book. I have had the lens over 5 months and used it mostly outdoors with a monopod. A monopod is a must, Living next to Yellowstone Park I use this lens alot, however it is alittle heavy, and needs alot of light to get a perfect picture. Its not a L lens but it has its qualities that are very close, this lens doesn't get the attention it deserves for outdoor photography.
If you are looking for a good F4 lens without spending over $ 900.00 this is a good alternative. If you shot in low light tripod is a must.
Overall I am very happy with this lens, I would give it 5 stars if it handled low light better.
Sigma 100-300mm f/4 EX DG IF HSM ...- User Rating: Summary for Sigma 100-300mm f/4 EX DG IF HSM ...- Great Telephoto Zoom
Notes on Sigma 100-300mm f/4 EX DG IF HSM ...- I bought this lens to use with my Canon 30D for high school sports (soccer, football, baseball, etc). I already had the Sigma APO 70-200mm f/2.8 EX DG HSM Lens for Canon Digital SLR Cameras and needed more focal length. Like the 70-200 F/2.8, this lens is big, heavy, and built like a tank. The bare lens is about an inch longer than the 70-200, but the 100-300's hood is longer than the 70-200's hood.
The zoom and focus rings are wide and move smoothly with just the right amount of resistance. This lens is sharp wide open. At the overlapping focal lengths, the 70-200 at F/4 is just barely sharper than this lens at F/4 (wide open). At 200mm, this lens is actually sharper (200mm is this lens's sweet spot.) At 300mm, the lens is still sharp wide open, but I like to stop down to F/4.5 just to keep things super-sharp. Up to 250mm, I would not hesitate to use it wide open.
This Sigma lens has HSM which means the focus is fast and quiet. The lens focuses a little slower than the 70-200 F/2.8, but I've found that the 30D is more of a limiting factor in focus speed than the lens is. Servo tracking is very good with this lens, the only time it can't keep up is when track runners are sprinting straight at me (although again, I think the body is the limiting factor here.) For almost every other situation, the focus will definitely keep up.
All in all, this is not an indoor lens by any means, but as an outdoor sports (or wildlife/nature) lens, it is awesome.
Sigma 100-300mm f/4 EX DG IF HSM ...- User Rating: Summary for Sigma 100-300mm f/4 EX DG IF HSM ...- Blazing fast focusing!!
Notes on Sigma 100-300mm f/4 EX DG IF HSM ...- The HSM of this lens is faster than Nikon 80-200 on D70s (it hunt around 2 times when i tried to focus on my frd who was in blue/white stripes at opposite side of a tennis court walking to me) and Sigma 70-200 on 350D. How fast is that? I could say that it is as fast as the EF-S 18-55 kit lens! Do bear in mind, usually wide lenses focuses faster than tele.
Besides, the handling and build of this lens is good. Tripod mount made of metal. Holding the tripod ring and focusing ring feels great. I shaked this lens on intention, and hit it to a table... ( this is not my lens :P ) It works same well and not even a tiny scratch is done on the lens after all
However, it has some draw backs. 300mm focal length is a bit too long for me. F4.0 is a bit too narrow to use with 300mm indoor ... your photos may be blurred if you handheld them
Conclusion: It is a perfect lens (especially sports) if you use it under bright sunlight.
