Official Pentax K to Q lens adapter

Started Aug 25, 2011 | Discussions thread
MightyMike Forum Pro • Posts: 40,571
Re: Official Pentax K to Q lens adapter

godfrog wrote:

Your 77mm F1.8 does not "become" a 431mm F1.8. It most certainly remains 77mm F1.8.

Not arguing that

In terms of field of view, depth of field and total shot noise it will be like using a 287mm F6.7 on APS-C, except resolution will be miserable,

Not sure about the resolution being miserable, without including NR the resolution should be that of the capability of the lens itself assuming the sensor out resolves the lens.

focus throw will be super short, mechanical tolerances much wider than what is used on 1/2.3" sensors,

Hold on here, a larger sensor requires finer tolerances for more precision, i believe therefore it will be the other way around. BTW the focus throw of the 77 is 120 degrees, the focus throw of my 100-300mm F4 is about 60 degrees... the focus throw doesn't change because you're on a different sized sensor

internal reflections from the lack of mechanical vignetting will zap contrast,

If this were true then the centers of all our photos would be equally bad regardless of the sensor size

and you'll have a lot less dynamic range in scenes where there is enough light to use base ISO on the APS-C camera.

Hmmm... maybe a lot less then 14.5 stops but looking at DXO for comparison sake we could expect 10-11 stops and that similar to what we were getting just a few years back on DSLRs, about the same amount of stops you get from m43rds or about the same you've get using ISO800-1600 on the K-5 ... not a big deal.

Oh, and the Q does not have a mechanically shutter, so you will have the image degradation of using an electronic shutter as well.

Sometimes this could be useful

Alternatively, the adapter will contain a leaf shutter with limited top speed as well as the issues associated with putting shutters at any point besides the focal plane or the middle of a lens, see Joseph Wisniewski's elaboration in this thread:

Yes there are those such issues
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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