I gave a lot of thought to purchasing this lens to photograph birds. I've yet to get the beautiful kind of shots I expected from it. Mostly it is quite difficult to get in a position to use the lens to its best advantage and full capacity.

Excellent optically and gives unparalleled reach and ability to frame shots. Heavy and demands care in handling. Before purchase I tried 600mm f4 and could detect little difference in quality. The flexibility of the zoom made the decision on purchase easy.

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  Extreme reach, Sharp, Brilliant rotating filter system

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  Heavy (but this is unavoidable) Finish is good but not great. Attracts lots of attention. Case provided is OK for storage but not for carrying. I have a Lowepro Super Trekker which will carry this and a range of other kit.

I finally pulled the trigger and purchased this lens. As others have stated, it's a heavy lens, and requires a heavy duty tripod. As for heads, I find the gimbal head to be the best for this lens, as well as safest. It focuses quickly. The images are very sharp. This lens isn't for everyone.

Great lens in my book. Despite of the weight, this lens is great for birding. I managed to get great photos of bulbuls, sunbirds, and other tropical birds which was probably 150 yards away from me. Tripod is a must I'm afraid.

Love this lens. I'm 70, so it's a job moving it around. I have a cart for it and my tripod setup, if I have to walk any distance. Great pics, fast focus. 300mm lets you locate then zoom in. This is my stationary location lens. The 150 600mm is my walk around lens.

SIGMA really needs to stop raising the price of this lens and add it's Optical Image Stabilization O.S.I owned this lens for two years early in it's production run. I shot it mated to then new EOS 1D MkII (which gives you an idea of when I had it)New versions have come out and the price keeps going...

This is the second one of these lenses that I have owned, one for Nikon and now the Canon version. This lens is heavy, but ruggedly built. It takes excellent photographs using the proper techniques.

Use this product for my hobby of wildlife photography. Could not be happier!!!

Just purchased the lens and have only used it for a few weeks - but it is outstanding. This lens is not for inexperienced photographers. You need to use a tripod, although I got great shots balancing it on my car window (fast shutter speed).

Hope over experience when I bought this one but I confess to being obsessed with focal length. You can see things you'd never normally see with a big lens. This 'sigmonster' is about the same size a Nikkor 500mm and about the same weight. You can easily hand hold it.