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08-23-2008, 12:00 PM   #1
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Polarizing Filter.

I just discovered that I cannot focus my Sigma 70-300 F4-5.6 DG Macro lens with a new Massa CPL. (Cheap Filter)?

It will focus between 70-100mm, but above it's out of focus, even when auto focus beeps. Can't manual focus either!

I use the same brand with the 18-55 smc Pentax DA with no problems.

Anyone else have this problem?

No problems with the UV filter.


08-23-2008, 12:50 PM   #2
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Location: Dubrovnik, Croatia
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It's probably some cheap filter. I had some CPL on Canon S3 IS, got it for few bucks, and it couldn't focus on longer focal distances, but it wasn't because of AF but because of filter, 'cause it just was blur with full zoom.
On smc DA 55-200 I have Marumi CPL and there's no any problem with image clarity. Just try that Sigma with some better quality filter
08-23-2008, 01:08 PM   #3
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Original Poster
Thank you Spex, I suspected that as the cause, but wanted to see what experience others have had. Yes it was a cheap lense and I will be getting a good quality one soon!

Thanks again!


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