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12-19-2015, 11:12 AM   #1
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DA* 55mm is slow to focus, is it the SDM?

My DA* 55mm has become slow to autofocus or won't attain focus at all. This happens with both PDAF and CDAF and on two different K30s which seems to tell me it's the lens and not the camera. I have tried cleaning the front and rear lens glass with a cloth and rocket air but it has not helped. Is there anything else I can do to be sure it is the SDM? I hope it is not as this lens does not appear to have a screw drive option.

12-19-2015, 11:14 AM   #2
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Make sure the lens contacts are clean, last time I had this happen I had to replace the lens contacts on my DA*60-250. The other recent time with the Sigma 18-250, it needed parts and servicing.
12-19-2015, 11:38 AM   #3
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QuoteOriginally posted by normhead Quote
Make sure the lens contacts are clean, last time I had this happen I had to replace the lens contacts on my DA*60-250. The other recent time with the Sigma 18-250, it needed parts and servicing.
The contacts look clean and I've wiped them off. Do they need to be cleaned with a particular solution?
12-19-2015, 11:53 AM   #4
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The issue with mine turned out to be that one had broken off, but before that, I'm pretty sure that they had somehow become deformed and were no longer making contact.

12-19-2015, 12:17 PM   #5
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You could try cleaning the contacts with a rubber/eraser. Just make sure you don't let any bits of it get into your camera.
12-19-2015, 01:26 PM   #6
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The focus has some success against contrasty backgrounds. It has nearly no success against dark backgrounds without contrast (such as a black drape).
12-19-2015, 02:35 PM   #7
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QuoteOriginally posted by Newtophotos Quote
It has nearly no success against dark backgrounds without contrast (such as a black drape).
Understanding Camera Autofocus
12-19-2015, 04:07 PM   #8
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Hm, the *55 is not known for SDM problems.
But the image quality is fine if you use manual focus? and if you select Av mode on camera and try f2, f14, the lens' aperture gets stopped down correctly?

Do your cameras focus faster and better with your other lenses?

12-19-2015, 05:31 PM   #9
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QuoteOriginally posted by Na Horuk Quote
Hm, the *55 is not known for SDM problems.
But the image quality is fine if you use manual focus? and if you select Av mode on camera and try f2, f14, the lens' aperture gets stopped down correctly?

Do your cameras focus faster and better with your other lenses?
The lens does stop down to the correct Aperture in Av, tried it from f2 to f20.

Interesting my DA* 16-50mm (seemingly the SDM failure queen) at 50mm can autofocus where the *55mm can't, even on all black fabric.
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