I have purchased two examples of this lens the first was the non DG and was used on the Canon 10D

Example image

http://www.worldphotographyforum.com...500&ppuser=133

http://www.worldphotographyforum.com...0&limit=recent

The second version was the newer DG edition which is supposed to reduce internal reflections. This has been used extensively on my Canon 20D it has Sigma's HSM motor for high speed focus and minimum aperture of f6.3 although on a Canon 20D this shows as f5.6

Example images

http://www.worldphotographyforum.com...500&ppuser=133

http://www.worldphotographyforum.com...500&ppuser=133

The lens is very heavy weighing in at around 1.8Kg but its well built with a twist action zoom and a lock to prevent the lens from extending when not in use. Even though its heavy I can hand hold down to a shutter speed of around 1/90 the deer shot above was taken at 1/180. The lens is sharp all the way through its focal length and much sharper than my last Canon 100-400L also its about half the cost. The sweet spot for sharpness is around f8 but its still acceptable at f5.6 (6.3) when zoomed in to 500mm. Filter size is 86mm and I would recommend the fitting of an EX glass filter the cheaper filters do affect image quality.

For the cost of around £600 new including case and three year warranty (Canon only give one year) this is a superb lens for both wildlife and aviation and well recommended.

Kevin