So, what is THE lens for 4/3?

Started Feb 16, 2011 | Discussions thread
_vlad
Contributing MemberPosts: 584Gear list
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Re: When it comes to sharpness....
In reply to Steve Bingham, Feb 17, 2011

Steve - obviously you can't do proper test (MFT) at home. AFAIK MFT is mapping the downfall of contrast from 100% to typically 50% at different lp/mm. All I could do was to pick the resolution graph take a photo at standardized distance (for the one I have is 50xfocal length) and pixel peep. This resolution chart has steps by 5 lp/mm from 25 lines to 100 lines and is printed as squares with 45 degree revolution per each segment. Line as per definition is one white+one black stripe.

So with this setup used for nearly 20 years I just picked up some films when Pentax resolved in the centre at best AV in the centre app. 110 lp/mm. And then after years I fit the same lens to GH2 again with AV 5,6 - obviously RAW, 160ISO and processed the files with best RAW converter detail-wise I am aware of - RAW Therapee with deconvolution sharpening and AMAZE demosaicing algorithm. Then I coupled the GH2 with 14-140 and just for fun with 14-42 and did the same. With all three lenses sensor started to show beyond 70lp/mm those strange square-like artifatcs when it is clear that the lens has still some "power" however sensor has not. BTW 14,3 MP Pentax K20D with 1,4/50mm Pentax prime stopped at 60 lp/mm.

That is all. Everything was set to 50mm eq (i.e. 25mm for 14-140 and 14-42 due to crop factor).

However Pentax prime unlike zooms has quite unique rendering so even I can't measure-up this factor under some conditions it is quite obvious. Pentaxians call it the difference between DA lenses and FA lenses.
Sorry to make the answer so long - just want to explain my procedure.
cheers
--
Vlad

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