Anybody have feedback on this lens?  Found a good example for a low price.  Not a lot of on line reviews.  It will be going on a D850.  Thanks in advance.

Is it the Sigma 300mm f/2.8 EX DG HSM APO?  Been discontinued a while (3 years) and was introduced in 2009.  That's an okay lens, but on 24mp cameras it's known to be a touch soft compared to other lenses like the Nikon 300mm f/2.8.  So it'll likely have troubles with the 45mp on the D850.  No VR on the lens either, so you'll really be needing to keep an eye on your shutter speeds to keep it from blurring.

KEH doesn't even have them in stock anymore, but tagged them at $400 when they did.  Personally it would be a really iffy buy for me.  If you could play with it before hand, run an AF test for sharpness, etc, it could be a yes with caveats.

It is the lens you mentioned.  $400 seems ridiculously cheap. I guess I got here too late.  I got the lens. slow to focus, noisy, doesn’t seem sharp.  I’m going to return it and rent a Nikon.  I’m sure I’ll regret it.  Thanks for your counsel in this and my “pole insyde” thread.

I'm surprised. Usually the HSM lenses are very good. I absolutely love my 70-200/2.8.