amfoto1 Loc: San Jose, Calif. USA

The Sigma 150-500mm originally was offered without OS (image stabilization)... If at all possible, get the later OS version. You'll be happy you did!

If the now discontinued 150-500mm is too big and heavy, Sigma also made a slightly smaller 120-400mm that's pretty darned good. It also was originally made without OS, later was offered with it, and is now a discontinued model.

There also was a Sigma 50-500mm produced in both OS and non-OS versions... It's nicknamed "The BIGma" for reasons you can probably figure out and would notice if you used it. Purportedly, of the three (150-500, 120-400 and 50-500) this was the sharpest at the longest telephoto focal lengths. It's also discontinued.

These lenses tend to run about $450 to $600 used, one reason you might choose one of them over the current 150-600 "C" ($1100) or the 150-600 "S" ($2000).

None of those lenses are particularly useful with teleconverters, because they're all f5.6 or f6.3 at their longer focal lengths.

There also is the Sigma 120-300mm f2.8... both a later OS version and an earlier non-OS. This lens works very well with 1.4X and 2X TCs. But it's larger, heavier than any of the above and a lot more expensive. The OS version is still in production and sells for about $3500 new for the lens alone. By the time you add one or two high quality TCs you are close to $4000 invested. The OS version can be found a little under $3000 used... While the earlier non-OS might be found for around $1500 or less.
If you don't already have one, at least get a monopod. These lenses are hand-holdable... but your arm will get tired and the support will come in handy anytime you shoot with it for more than a few minutes.

If you want to use a tripod with these lenses to shoot moving subjects, consider a gimbal head. These relatively affordable super-zooms are not IF (internal focusing) lenses, so they change length when zoomed or focused, and that in turn changes the precise balance that can be important when using a gimbal head. A gimbal head with some dampening like the Nest may work better with non-IF lenses such as these.

You didn't mention what camera brand you are using... some of these lenses may not be available for certain brands. And there might be some OEM lenses worth consider, too (Nikon 200-500... Canon 100-400... etc.).

the f/stops here Loc: New Mexico

Woodworm, I've had that lens but found one problem. The location of the focus ring is in front of the zoom ring, where my fat fingers would find there way to it when holding the lens. Therefore the auto-focus didn't work because I was holding the focus ring. I replaced that lens with the Tamron 150-600mm which has the focus ring located near the camera body and have never had that problem again. Plus the Tamron seems to provide sharper images. Best, J. Goffe

cjc2 Loc: Hellertown PA

Th answer to this lies, at least partially, with how much you wish to spend. Generally speaking, newer optics are better than the older ones due to the advances made by the manufacturers -- but not always! Whatever lens you do buy, please don't fall into the false belief that all you shots, out of the box, will be awesome. They will not, as there is a steep learning curve with long telephotos which can only be overcome by practice! That's the fun! I own the Sigma 150-600 Sport and like it better than the Tamron that I tested, but am thinking of switching to the Nikon after I get the opportunity to work with one. Best of luck.

Fotoserj Loc: St calixte Qc Ca

Bought mine a couple weeks ago and haven't really put it true the test but so far I'm very please

Fotoserj Loc: St calixte Qc Ca

I envy you I've never been in position to take such nice shot

cambriaman Loc: Central CA Coast

IO have had my 150-500mm Sigma since 2010. It served me very well on my African safari that year. Here is one of the first images I captured with it.

Mark7829 Loc: Calfornia

As much as I like the images, I don't see lens quality at all. I see light and composition. Posting images falls far short in evaluating lenses. There are like 10 different criteria that I can think of that are important. If you make a decision based upon images posted, you're making a mistake.

Bushymonster Loc: Oklahoma City. OK.

Nice shot. I wished I could go to Africa on a safari.
-Bushy
I wasn't going to say anything but I was brought up respectfully and was told if you couldn't say something nice not to say anything. Unless your opinion was ask.

wotsmith Loc: Nashville TN

Carlo,
I am impressed with your hawk photos especially the last one posted. I don't know what your lens cost, but it is pretty good. I shoot with a 600 f4.0 that was very expensive, and I get fabulous photos with it (long learning curve to get good) and I would argue that it would be slightly sharper, but not by much!
You should be proud.
Bill

wotsmith Loc: Nashville TN

Hey Carlo,
One more suggestion for your photos; the top two especially could have stood some fill flash. I use a better beamer a lot and have actually put useful light on an eagle's nest 200 -300 feet away. Only $70
Think about it
Bill

Bret Loc: Dayton Ohio

Here's one with that lens I got a few weeks ago...and its no slouch of a lens.

(Download)

Carlo Loc: Maryland, NW.Chesapeake Bay

Agree..!! :thumbup:

Bushymonster Loc: Oklahoma City. OK.

Awesome picture. I would like to see wotsmith's awesome pictures...
-Bushy

Rick from NY Loc: Sarasota FL

deleted - my misread of qestion

Bobspez Loc: Southern NJ, USA

I had the Bigma briefly and sent it back. But I tested it on a DX Nikon and did not find it to be particularly sharp at 100% crop and 500mm. I got better results putting the Nikkor AFS VR 55-300mm zoom on a Nikon J1 (CX sensor) with the FT1 f-mount adapter. With an 810mm equivalent focal length, the 55-300 gave me better results than the Bigma on a DX at full zoom.