8-16 Sigma soft?

Committed to my swap over to Pentax I tried the above lens - and also the 10-24 Tamron which I used to own on my Nikon at SRS earlier today and to my surprise the images were soft. From both of them... So I left them for the time being until I can try a 12-24 Pentax see if it is any different but could you share your experiences with the 8-16?

Thanks!

http://forums.dpreview.com/forums/readflat.asp?forum=1036&message=38272388&q=mah...
Check out Mahesh's pictures with that lens. Doesn't seem soft
Pete

Hm could it have been the copy I tried then? or maybe it was me cause the Tamron got the same kinda fuzziness...

Sometimes I have to resort to live view to get good focus on my 10-20mm. I don't think it's a BF/FF thing, just the AF system struggling to find something to lock on to. I can point my 10-20 at a nearby boulder, it focuses, but then I point it at infinity and the AF doesn't kick in! I'm sure I remember someone making similar comments about their 12-24mm, could be a general UWA thing.

Hm the K-5 was focusing without a problem both near and far.

What you describe was extremely evident on my D40+10-24 I think it has a lot to do with the sophistication of the AF system + UWA. Put the same lens on the D7000 it was focusing perfectly accurately and fast on D40 it could struggle to acquire focus anywhere beyond 6-7 feet. The 12-24 though did not have the same problem.

I think my tests were a bit flawed though, for starters there were quite strong winds so the subjects could have been shaking a bit also I realised half way through that I was shooting at f20 - dont ask why.

I will wait for their call though to see if the 12-24 comes in stock and go have another round of tests when it does.

f20 won't be helping sharpness much...

You might have more luck with the 12-24mm. Bit less wide, a bit brighter aperture.

Some superb pics HERE from the 8-16mm.

Makes me want to get rid of my Sigma 12-24mm

Some serious cropping on the aerial shots- must be a sharp lens

These are really nice pics. Love the colours too.

Not too much distortion when considering the width either, would give me 2mm more than my 10-20.

Mmmm

I found this technique from PhaseOne to be a very useful exercise

Surprising how much better things got with the DA12-24

Matt

I would presume only the first 3 were with a UWA lens .. he used a variety of focal lengths if you read the entire post.

Mine isn't.

Likewise - for that I could use a P&S with a sensor the size of my little finger nail...

Regarding the OP's question, the Sigma is very soft at f22 due to diffraction. At wide apertures it is sharp although it does benefit from stopping down a couple of stops.