Official Pentax K to Q lens adapter

Started Aug 25, 2011 | Discussions thread
MightyMike Forum Pro • Posts: 40,573
Re: Official Pentax K to Q lens adapter

I hear where you are coming from but i think you're exaggerating the problems a little more then realistic... I'm sure Pentax considers the same issues before making an adapter, essentially if its crap not many people will buy it and there is no point in making it.

BTW the Contrast and resolving capability of the 77Ltd peak at F4.0 and at still good at F2.8, and decent at F1.8/2.0. Also diffraction doesn't suddenly drop the IQ its quite a bit more gradual, I remember on the FZ30 i believe the diffraction limit was F5.0 but it was sharpest(best res. or contrast or both) at F7.1. Just look at any lens review where it shows smaller apertures, it takes quite a few stops past the diffraction limit before the resolution drops by a factor of 2.

The 77Ltd peaks at F4.0 at 48.5lpmm on the K20D on a lenstip review... it takes until F14 before the res. drops by a factor of 1.4 and F22 before it drops by a factor of 2 from its peak.

EDIT add: I forgot to mention that both my Tamron 300/2.8 and 400/4 have a focus throw of approx. 120 degrees but my old M42 Alpex 200mm F3.5 has an impressive focus throw of 270 degrees. I think when it comes to telephoto what is most important is how long its focus throw is at longer ranges. My 800mm F8 has a 90 degree focus throw but it jumps out of focus with just breathing on it a near infinity ranges
Mike from Canada

"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'

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