:confused: I've read so many articles about telephoto/zooms i don't know what to believe anymore? Some say great lens,some say not so great. What do you think? Hear is the problem, Money! First, what i would use this lens for is nature,wildlife,and some sports, nephews little league games which are sometimes late in the evening. Also would like to keep the cost to less than $1400.00. My considerations so far are: 1)canon 100-400IS 2)canon 300f/4IS 3)Sigma 50-500. What do you think? Have any suggestions, comments etc... thanks for your reply!

all 3 serve a purpose, but not all will fit your subject matter 100%

sigma.... large, need tripod at long end f6.3(1/3 over f5.6) at 500mm

300f4...... fixed, semi fast and the lightest of your choices, sharp

100-400...zoom, pretty sharp! f5.6.... high iso in low light

btw... all 3 lenses rock for the price and produce razor sharp images in optimal conditions

wildlife..... reach is good

sports, fast / handholding would be best bet

I have personally owned the 100-400 IS, and the 300 f/4IS. Both take excellent photos, and optically are terrific performers. I have shot minor league baseball from the left field bleachers with the 300 IS with a 1.4 teleconverter and gotten excellent shots of the batter, catcher, umpire. Here's an example attached.

I still own the 300 f/4 IS, but traded the 100-400 IS for a 35-350 L because that lens better met my needs at the time. The 10x zoom range was terrific with an EOS 3, but not so usedful with a D-30 and 10D. So, I ended up trading the 35-350 for a 16-35 2.8L

Anyway, one other lens you should consider is the 70-200 2.8L Talk about sharp, talk about spectacular image quality. Man, that is THE lens to own in the Canon lineup as far as telephoto zoom. Really, you can't go wrong with it. If you want a longer reach, get a teleconverter. However, I rarely need a TC with the 70-200, and have never been dissatisfied with any photo taken with it.

Note: attached photo taken with a 10D, ISO 800, with a 300 f/4 IS with Kenko Pro 300 1.4x teleconverter, approximately 320 feet from home plate in the left field bleachers.