Does K-5's AF Fine Tune work on your Sigma HSM lens?

AdrianM · 11-20-2010, 03:29 PM

The Sigma 70-200 f2.8 HSM II is a very fussy lens, and I have fiddled with the focus adjusrtment for it for a couple of years but have been unable to come up with a consistent assessment of the focus point. To add to the problem, the lens is a little soft wide open to begin with, so the focusing system seems to have trouble with it as well. I have gone from full back focus adjustment (-10) to +5 at various times. The only solution I have found is to stop it down a bit, but what's the point of a 2.8 if you can't use it.

m8o · 11-20-2010, 10:16 PM

Originally posted by AdrianM

The Sigma 70-200 f2.8 HSM II is a very fussy lens, and I have fiddled with the focus adjusrtment for it for a couple of years but have been unable to come up with a consistent assessment of the focus point. To add to the problem, the lens is a little soft wide open to begin with, so the focusing system seems to have trouble with it as well. I have gone from full back focus adjustment (-10) to +5 at various times. The only solution I have found is to stop it down a bit, but what's the point of a 2.8 if you can't use it.

Thanx for the input. Sgma USA is a few miles away from me. I may drive my K-5 and 70-200/2.8 over there.

I'll add however, I only found soft wide open at/near 200mm, at/near MFD. I've found it to be pretty nice, correction, very nice at much longer focus distances.

I'd have to say this f/2.8 definitely has allowed me to quickly lock onto focus where an f/4 lens would have had trouble.

---------- Post added 11-21-10 at 01:39 AM ----------

p.s. ... I guess it's worth mentioning I actually found this lens to have great focus at/near infinity, and incredible resolving power when coupled with the K-5.

You can click the image then click the "Get Original Uploaded Photo" link to inspect the detail. I did some light pp on a JPG on this photo, as Lightroom doesn't recognize K-5 PEFs yet, and a SilkyPix converted DNG doesn't work either.

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11-20-2010, 03:29 PM	#16
AdrianM Pentaxian Join Date: Aug 2008 Location: Ipswich, Queensland, Australia Photos: Gallery \| Albums Posts: 589	The Sigma 70-200 f2.8 HSM II is a very fussy lens, and I have fiddled with the focus adjusrtment for it for a couple of years but have been unable to come up with a consistent assessment of the focus point. To add to the problem, the lens is a little soft wide open to begin with, so the focusing system seems to have trouble with it as well. I have gone from full back focus adjustment (-10) to +5 at various times. The only solution I have found is to stop it down a bit, but what's the point of a 2.8 if you can't use it.

11-20-2010, 10:16 PM	#17
m8o Veteran Member Join Date: Jul 2007 Location: 40°-55'-44" N / 73°-24'-07" W [on LI] Photos: Gallery \| Albums Posts: 3,092 Original Poster	Originally posted by AdrianM The Sigma 70-200 f2.8 HSM II is a very fussy lens, and I have fiddled with the focus adjusrtment for it for a couple of years but have been unable to come up with a consistent assessment of the focus point. To add to the problem, the lens is a little soft wide open to begin with, so the focusing system seems to have trouble with it as well. I have gone from full back focus adjustment (-10) to +5 at various times. The only solution I have found is to stop it down a bit, but what's the point of a 2.8 if you can't use it. Thanx for the input. Sgma USA is a few miles away from me. I may drive my K-5 and 70-200/2.8 over there. I'll add however, I only found soft wide open at/near 200mm, at/near MFD. I've found it to be pretty nice, correction, very nice at much longer focus distances. I'd have to say this f/2.8 definitely has allowed me to quickly lock onto focus where an f/4 lens would have had trouble. ---------- Post added 11-21-10 at 01:39 AM ---------- p.s. ... I guess it's worth mentioning I actually found this lens to have great focus at/near infinity, and incredible resolving power when coupled with the K-5. You can click the image then click the "Get Original Uploaded Photo" link to inspect the detail. I did some light pp on a JPG on this photo, as Lightroom doesn't recognize K-5 PEFs yet, and a SilkyPix converted DNG doesn't work either.