Sigma 500mm f/4.5 EX DG APO Autofocus Lens for Pentax AF USA

Comments about Sigma 500mm f/4.5 EX DG APO Autofocus Lens for Pentax AF:

This is a very sharp lens. I have a lot of excellent lenses in my kit, including Pentax DA* and FA limiteds, but this is by far the best piece of glass.

For birders, this on a Pentax K-5 is arguably the best thing going. It is a pound or two lighter and thousands of dollars less expensive than the Nikon or Canon OEM 500mm lenses. And thanks to Pentax in-body shake reduction and the relatively light weight I can hike a couple of miles with it on a BlackRapids shoulder harness without having to take aspirin that night (I'm an older guy) and fire off hand-held shots with ease and accuracy.

It is unfortunate that Sigma charges the same for the Pentax version as the Nikon and Canon versions, which have image stabilization and ultrasonic moters, whereas the Pentax model has screw drive and no built-in IS. But the Pentax version works as well and doesn't weigh as much so despite the downgraded features it is a winner. The lens performs very well with a Tamron 1.4x Pz-AF teleconverter, giving a reach on a APS-C sensor of a bit more than a 1000mm equivalent on a full frame camera.

On the negative side, the lens case is of high quality but basically useless everyday because the lens hood has to be removed and reversed to fit and the strap is cosmetic rather than functional. The lens foot/handle is a couple of inches shorter than desirable for balancing the lens on a monopod/tripod with a camera attached. Finally, the lens will not take a front UV filter so to protect this puppy you need to keep the hood permanently in place.

But these are quibbles. You won't be sorry if you buy this lens.

Comments about Sigma 500mm f/4.5 EX DG APO Autofocus Lens for Pentax AF:

It has taken a long time to take this glass from my wish list to reality. I am still going wow every time I use it. It is much, much better than any long telephoto I have owned. I am stunned by the detail that comes up in dark bird feathers. It is a magic match with the Pentax K5. It has taken my telephoto photography a massive leap forwards.

I am very satisfied with the screw focusing and focusing speed is faster than i expected. I would think manual focusing would be a breeze.

I was expecting it to be much heavier and more difficult to hold. It has a solid handle that one can grip with their full hand. As yet i have not bothered putting it on a tripod or monopod. I find I can hand hold and if I can I will rest my arm on something.

I was expecting a plastic lens shade, however it is solid metal and a thumb screw makes sure it does not slip off.

I would think that it is no where near weather proof and rain could easily get in. I think the black coating will scuff up quickly.

I suspect the lens will present 3 problems:
1. taking it on aircarft with the rest of my kit
2. where to put in in my car so I can have easy access.
3. what i will match it with when 500mm is too long.

I think I am happy to live with these problems.

Comments about Sigma 500mm f/4.5 EX DG APO Autofocus Lens for Pentax AF:

I'm still in the get-acquainted stage but there's no doubt this is a serious state-of-the-art telephoto. It's useably sharp wide-open and very sharp from f5.6 up. Color rendering and bokeh are very nice. For a 500mm, it's remarkably easy to handle and I love that you can rotate the (included) CPL filter. The only thing it's missing IMHO is a focus limiter.