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07-20-2013, 04:18 AM   #1
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Pentax A* 85mm f1.4 issue

I have a A*85mm 1.4 lens which has following issue:
- Pictures are sharp up to f 4.0
- As soon I go below 4.0 pictures start to getblurry
- I tried lens on K5 in Av mode on A setting as wellas M and respective aperture setting like 2.8, 2.0, 1.6 etc. with same results.

First I taught it might be the aperture blades but when in Mmode and aperture set on ring I had same problem.
Glass is very clean and no haze and blades do not show anywear.

Anyone having a ideawhat might be the issue here.

07-20-2013, 05:04 AM   #2
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Out of focus most likely?
It's not like the aperture has a very huge effect on the global image quality, afterall the elements stay the same regardsless the aperture.
07-20-2013, 05:13 AM   #3
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Try to post some examples. Focus issues become more sensitive at large aperture (low f), and thus might explain your trouble.
07-20-2013, 05:22 AM   #4
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Yeah, it might be that the DoF is just so thin. Also, if you have any filters, take them off. There are some threads on how to use a focus chart, and these can also be used to test the overall lens sharpness, so feel free to look at those.
Thats a great lens, it would be too bad if its not working properly.

Edit: but some examples, with intact exif, would be great

Last edited by Na Horuk; 07-20-2013 at 09:18 AM.
07-20-2013, 08:01 AM   #5
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Pentax A* 85mm f1.4 issue

Thank you all for your replay. I will contact Eric and see what he thinks
07-21-2013, 07:03 PM   #6
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Sticky aperture blades? Had the same issue with my A50 Macro.
07-21-2013, 07:05 PM   #7
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Definitely post some pictures, and make sure you're focusing in live view with magnification on

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07-22-2013, 01:21 AM   #8
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Pentax A* 85 mm 1.4

Lens will be sent to Eric today. Hope he is able to find cause.


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