Gotta love this new Sigma 2.8 70-200mm HSM APO lens I got couple weeks ago.

I did learn that anything at 200mm range will need an F stop of 4.8 or so to make it a sharp photo. Other than that, 2.8 at about 1/180 using my Nikon D50 seemed to do the trick.

It was a lower league so the guys weren't amazing at skating so there aren't too many great action shots but still very useable. Enhanced alittle with AutoCorrections in Photoshop.

Gallery:
http://greatsave9.smugmug.com/gallery/2887607#P-9-15
http://greatsave9.smugmug.com/photos/155209298-L.jpg

http://greatsave9.smugmug.com/photos/155198319-L.jpg

http://greatsave9.smugmug.com/photos/155208546-L.jpg

if the lens isn't sharp wide open, you may have a defective copy. Some lenses are pretty soft wide open, but the sigma 70-200 should not be one of those lenses. If you're noticing an obvious difference, I would contact sigma. You shouldn't have to shoot at f/4.8 at 200mm. That's really only a characeristic of the cheap zooms (70-300 f/4-5.6) and for a 700 dollar lens you shouldn't be having a big problem with it. do a sharpness test with it on a brick wall and make sure the reason the images aren't sharp is just because the shallow DOF makes things blurry when you don't nail the focus. Make sure it's almost as sharp at f/2.8 as it is at f/4-5.6, because the sweet spot for most lenses is 1-2 stops stopped down.

If it were a Canon lens you could ship and the body to Canon and have it adjusted for the sharpest photos at f2.8 or whatever f stop you want. Many of the pro's do this at f4 or around there. Most Canon lenses are set to be sharpest around f8 or f9, I forget, but it's around that point. You will find lenses that work different at different f stops, and with cheaper lenses they can be all over the board.

One thing that you may want to check is to see if your getting fluctuations of sharpness at the same f-stops. Say you take 10 shots at f2.8 and 2 or 3 are sharp and the rest not so sharp or vice versa, then the problem could actually be a LOOSE BARRELL, You can check that easily enough by holding both ends of the lans and seeing if it moves or feels loose. Check it fully extended as well. If it feels loose then the problem is probably a loose barrell and it is very common in less expensive lenses, especially Vivitar and Tamron lenses. It's an easy fix for the techs and most companies fix them free or very cheap.
What happens is the photos will be soft because the barrell is out of alignment.

JS

If your copy isn't very sharp at F2.8, I'd definetely have it checked out. Mine is tack sharp at F2.8 at 70mm through 200mm

Thx everyone for the comments, maybe I will have it checked out.

I also forgot to mention, its the MACRO lense, would that have anything to do with less sharpness at 200mm?

To run a test, I did 200mm at different F stops. You can click Photo Info and see for yourself as it got shaper at f4.8

http://greatsave9.smugmug.com/gallery/2871295#154111273



Here are 2 simliar pix, different F stop.
F2.8
http://greatsave9.smugmug.com/photos/154113278-L.jpg

F4.8
http://greatsave9.smugmug.com/photos/154113152-L.jpg

I'd get it checked out....

JS

yeah definitely. The CA on the first shot is something you only normally see on crappy lenses and when you combine it with a teleconverter. and i can definitely see what you mean from your photos about it really only happening when you get close to 200mm at f/2.8.

After taking a closer look at the shot at f2.8 it appears that one of the elements isn't lined up correctly, similar to a loose barrell, except the element is loose or binding. If you look closely you see the lower center of the photo is blurred and gets sharper as you go higher up, thats an element alignment issue that can only be fixed by the maker.

JS

Thanks so much for the help! It hasnt even been 30 days with the lense. I contacted the store and they'll run some tests on it if I drop it off, and then send it back to Sigma for me. They called me personally an hour after I sent them an email. Great customer service. :thumbsup:
Thumbsup for New York Camera in Southampton, PA http://www.nycv.com/