Buying a big lens is a complicated experience as well as an expensive one also. After months and months of procrastination and waiting I decided to take the plunge. Why waiting - waiting to see if Nikon would introduce a new lens or institute a price reduction on their current 500mm f/4D ED-IF AF-S II Nikkor or for short Nikon AFS 500 f4, which is priced at a monstrous $7000+. Why procrastination - because considering a 500 made me also consider walking down the Canon route, their 500 is better than Nikon's offering, their cameras have better high ISO capabilities and the Canon EF 500mm f/4 IS (Image Stabilizer) USM is only $5000 (in the states, still $7000 in Bangkok, unfortunately).

So my choice seemed simple, a) continue to wait for Nikon to unroll their new FF D3 camera and their new 500 F2 lens, all the time hoping they will not come in at a price that will not break the bank or b) buy the Canon EF 500mm f/4 IS and use the savings to buy a Canon 5D and enter the world of long reach and high ISO performance.

As a long time devotee of Nikon and having an enormous amount of money invested in their system the choice was clear, buy the Canon!

I was literally on my way to the ATM to check there was enough cash in my account when one last web search brought up another contender. The Sigma 500mm f/4.5 EX HSM. At only $4000 I was interested, it was not a Canon or a Nikon but all of my current gear would work with it, it was lighter than both the Canon and Nikon as well as being physically smaller, but could it perform? Lets see....

The GOOD or What I Like

1) The lens has a fast maximum aperture F4.5 optimized for digital SLR cameras. Thats 0.5 slower than the Canon or Nikon, not enough to make me consider it a real disadvantage so long as I had no problems using autofocus/teleconvertors with my D2x (more below)

2) It has a 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. So far I have seen no evidence of flaring or ghosting but I have to be honest and say as a wildlife photographer I rarely take a shot unless the sun is behind me anyway.

3) 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. So much quality that this lens embarrasses some of my shorter lens. This lens is the equal of the Nikon - no questions.

4) 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. The rotatable drop-in filters are supplied with the camera so theres no nasty additional cost surprises like with the Canon and Nikon. They are a breeze to work with.

5) HSM (Hyper Sonic Motor for Sigma, Canon and Nikon mount lenses) works beautifully! It is fast and positive and more than a match for the Nikon.

6) Accepts both Nikon TC 1.4 x and 2X Tele-Converters. By adding a teleconverter you can use this lens as a 700mm F6.3 AF ultra-telephoto lens with a 1.4X teleconvertor, or as a 1000mm F9 MF ultra-telephoto lens with a 2X teleconverter. Working with my Nikon 1.4 teleconvertor there is no apparant loss of quality or autofocus speed which makes 700mm a breeze to handle. Working a 2X teleconvertor (both Nikon and Kenko) makes AF virtually useless except in very bright high contrast situations. This is the same with the Canon and Nikon offerings also.

Note to make a Nikon TC work with the Sigma you will need to perform a minor modification (requires a screwdriver and a file) to the actual teleconvertor. For details of the conversion Click Here. NOTE: Kenko TCs need no conversion to work.

7) Size. It is surprisingly manageable for a long lens. Ok, I do not recommend you hike with it or attempt to carry it around on the built in strap but as a semi-static lens that operates from a bean bag or tripod and occassionally hand held it works flawlessly.

The Bad or What I Would Change

1) I really dont like the lens cover and the hood operation. When the hood is in place you cannot fit the lens cover - you have to take it off to fit the cover. Its annoying.

2) Don't buy the LensCoat (camo cover). Admittedly its an add-on from another supplier not associated with Sigma, but be cautious. It just further complicates the whole shade and hood issue by additionally adding the complication that with the LensCoat in place you cannot fit the lens cover even when the shade is dismantled. Find an old dear with a sewing machine, buy a bit of thin camo cloth, some velcro and make your own - better quality, better usability and better price.

3) No Image Stabilization. The Canon has it, the Nikon does not. It's no replacement for good long lens technique but what the hell, the Canon has it and that sets the mark.

The CONCLUSION

Its a great wildlife and birders lens. Its available readily in Thailand, and its the cheapest current option for a Nikon user to get up 1000 mm of reach (even further with digital crop factors).
If you are a Canon user - for $5000 there is no question, buy the Canon EF 500mm f/4 IS.
If you are a Nikon user - for $7000 there is a big question. I would unreservedly buy the Sigma and spend the $3000 I saved for the achieving the same performance on something nice.

NB: There are rumors that when Nikon introduces the D3x it will also release details of a large number of new lens, one being the 500 f2 with VR. I mention this because there is also discussion in Nikon that for Nikon to pull back some of the ground it has lost to Canon that it will have to price its new lens at much lower prices because there simply aren't enough Nikon users left in the nature and sporting market segments to justify a simple lens upgrade - the upgrade will have to be part of overall cost/customer driven strategy. A sub 7000$ 500 mm f2 may be coming. Lets see.

The BASIC SPEC:

Sigma 500mm f/4.5 EX HSM
Focal Length: 500mm
Maximum Aperture: f/4.5
Lens Construction: 12 elements in nine groups (2 ELD elements)
Number Of Blades: Nine
Minimum Aperture: f/32
Minimum Focusing Distance: 13.1 ft (4 m)
Maximum Magnification: 1:7.7
Filter Size: 46mm, rear drop-in
Lens Hood: Bayonet type; included
Dimensions: 4.8x13.8" (123x350mm)
Weight: 6.81 lbs (3100 g)
AF Mounts: HSM Model: Canon, Nikon (D), Sigma SA
Accessories: Hood, circular polarizer, soft case; included