APO 500mm F4.5 EX DG/HSM

Data from Sigma web site, comments from Rusty Dodson

This ultra-telephoto lens has a fast maximum aperture, and also features a new super multi-layer coating, which optimizes the characteristics of digital SLR cameras. Two ELD glass elements in the front lens elements reduce chromatic aberration to a minimum and also ensure sharp, quality images of high contrast.

New coating reduces Ghost and Flare

The new multi layer lens coating and lens design reduce flare and ghost, which is a common problem with digital cameras and also creates an optimum color balance.

It is equipped with ELD (Extra Low Dispersion) glass elements

Two ELD glass elements in the front lens elements reduce chromatic aberration to a minimum and also ensure sharp, quality images of high contrast.

It also features a rotatable drop-in filter

It also features a drop-in 46mm filter holder in the rear part of the lens barrel, which can be rotated to facilitate the use of filters, including a polarizing filter.

HSM (Hyper Sonic Motor for Sigma, Canon and Nikon mount lenses)

The AF drive for Sigma SA, Canon and Nikon S.L.R. cameras features Sigma’s ultra-quiet and high-speed Hyper Sonic Motor (HSM).

Inner Focus

Inner focusing retains external dimensions for ease of handling.

Accepts both 1.4X and 2X APO EX Tele-Converters.

By adding an APO teleconverter (optional extra), you can use this lens as a 700mm F6.3 MF ultra-telephoto lens with a 1.4X EX teleconverter, or as a 1000mm F9 MF ultra-telephoto lens with a 2X teleconverter.

Note the lens I am discussing is not the current DG model.

If you're a Nikon shooter with a need for a fast super telephoto lens but just can't drop 10k on a lens yet, this is likely your best option.

The Sigma 500mm f4.5 EX HSM telephoto lens is in a class of it's own, it is easily the most affordable lens in the super telephoto class. It is still not a cheap lens, but if you're using this type of lens you probably need it. a 500mm f4.5 lens opens a whole new door in wildlife photography.

The Sigma 500mm f4.5 EX is a very good performer. I had previously stated that getting sharp images at f4.5 was difficult, however after a recent photo trip using my new gimbal type tripod head, it's a lot easier. With a good solid tripod and head the lens appears to be an excellent performer for the price and very close to the to the Nikon 500mm. Obviously the lens just gets sharper when it is stopped down.

The Sigma 500mm f4.5 HSM is a very quick lens. The autofocus will easily track medium to large birds in flight.

The lens is built well and still works flawlessly after years of use in both extreme cold and heat. I'm not crazy about the lens hood, it's a little short and has a flimsy attachment mechanism. In fact, I lost mine in the Yellowstone river thanks to that flimsy attachment mechanism.

If money is not an issue or if you're a professional photographer making a full time living off your images go for the Nikkor 500mm f4. As for the rest of the casual shooter and even part time professionals the Sigma 500mm f4.5 EX HSM lens is a close runner up.