Tamron Adaptall-2 on K5ii?

Started Apr 16, 2014 | Questions thread
Holger Bargen Senior Member • Posts: 2,670
Re: Tamron Adaptall-2 on K5ii?

I have the 180 mm f=2.5 Tamron lens and it works fine with the PKa adapter. The camera thinks it is 2.8 instead of 2.5. The difference is not very big I could correct it easily by correcting the exposure time a little - but the output without this correction si fine, too.

I've heard that there are problems with some of these adpters - some work fine - others do not. I could imagine that this has something to do with recognition of the maximum aperture - there are little points on the mount which can be isolated or not - I think the pattern of isolations give the code about the correct maximum aperture to the camera. If it's wrong it won't work. But this is my explanation of the problems and I do not know if it is true.

Best regards


 Holger Bargen's gear list:Holger Bargen's gear list
Pentax K-5 Pentax K-S1 Pentax K-1 Pentax smc DA 55-300mm F4.0-5.8 ED Sigma 70mm F2.8 EX DG Macro +5 more
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