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01-11-2016, 04:18 PM   #1
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m42 to Pentax K focal reducer

Hello everyone,
I recently stumbled upon the idea of a "focal reducer", and it seems that it is a dream come true since I have some great M42 lenses, obviously designed for 35mm film so focal adapter would make them wider and brighter which is ideal for me.
Unfortunately, to my disappointment I couldn't find one for M42 lenses and my Pentax K body.
I googled a fair amount of time but with no effect.
Maybe someone on this forum knows where I could find such accessory ? or even better, where can I buy one?
Legacy m42 lenses are popular amongst many photographers so surely someone is producing a focal adapter for K mount right ?

01-11-2016, 04:30 PM   #2
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In order for such a device to work, you not only need the smaller sensor (than the lens was designed for), but a closer registration distance. So while you can find them for m42 lenses (I think), the target format to use it on will be m4/3 mirrorless or similar. I wouldn't work for a Pentax K or m42 full-frame lens on a Pentax DSLR because the registration distance is the same -- needs to get closer to the sensor. One could be made for the Q in theory, but I doubt that will happen...
01-11-2016, 04:41 PM   #3
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vonBaloney speaks the unfortunate truth about the technical problems with such an adapter, I would also add that since Pentax is a small player, there is less incentive to third parties to develop K mount-specific adapters.

What *might* be technically possible is a 645 (or 67) to K mount focal reducer, but still the problem of limited demand remains.
01-11-2016, 04:48 PM   #4
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QuoteOriginally posted by maxfield_photo Quote
vonBaloney speaks the unfortunate truth about the technical problems with such an adapter, I would also add that since Pentax is a small player, there is less incentive to third parties to develop K mount-specific adapters.

What *might* be technically possible is a 645 (or 67) to K mount focal reducer, but still the problem of limited demand remains.
Maybe Samyang or Laowa will be tempted, seeing as they are making K mount stuff?

01-11-2016, 05:35 PM   #5
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QuoteOriginally posted by pathdoc Quote
Maybe Samyang or Laowa will be tempted, seeing as they are making K mount stuff?
Well no one is going to make a medium format to K (if that's even possible) -- there just are too few of those lenses out there. So you might possibly see a K->something, but that something will be a Sony mirrorless or other. So as far as shooting with a Pentax K-mount DSLR and using a focal reducer, that will never happen. (Just as it will also never happen for Nikon F mount or Canon EF mount cameras -- it is strictly a gimmick for small-sensor mirrorless cameras to use lenses designed for bigger DSLRs.)
01-11-2016, 06:00 PM   #6
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QuoteOriginally posted by vonBaloney Quote
Well no one is going to make a medium format to K (if that's even possible) -- there just are too few of those lenses out there. So you might possibly see a K->something, but that something will be a Sony mirrorless or other. So as far as shooting with a Pentax K-mount DSLR and using a focal reducer, that will never happen. (Just as it will also never happen for Nikon F mount or Canon EF mount cameras -- it is strictly a gimmick for small-sensor mirrorless cameras to use lenses designed for bigger DSLRs.)
That's incorrect. Kipon has announced a medium format focal reducer for Sony cameras.
01-11-2016, 06:15 PM   #7
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QuoteOriginally posted by raff89 Quote
Hello everyone,
I recently stumbled upon the idea of a "focal reducer", and it seems that it is a dream come true since I have some great M42 lenses, obviously designed for 35mm film so focal adapter would make them wider and brighter which is ideal for me.
Unfortunately, to my disappointment I couldn't find one for M42 lenses and my Pentax K body.
I googled a fair amount of time but with no effect.
Maybe someone on this forum knows where I could find such accessory ? or even better, where can I buy one?
Legacy m42 lenses are popular amongst many photographers so surely someone is producing a focal adapter for K mount right ?
A K mount or M42 to Sony E mount is the closest you're going to get, I think, as far as speed boosting Pentax lenses goes. They work nicely with the Sony A7 if you want to play around!

Adam
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01-11-2016, 06:29 PM   #8
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QuoteOriginally posted by fuent104 Quote
That's incorrect. Kipon has announced a medium format focal reducer for Sony cameras.
Indeed, I stand corrected. Not sure why anyone would want one (if you had the lenses already I guess), but anyway...

01-11-2016, 09:11 PM   #9
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QuoteOriginally posted by vonBaloney Quote
Indeed, I stand corrected. Not sure why anyone would want one (if you had the lenses already I guess), but anyway...
It's extremely clear why someone would want one, to me: it offers the ability use medium format image characteristics on smaller, cheaper camera bodies, with increased speed and resolution.
01-11-2016, 09:44 PM   #10
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QuoteOriginally posted by fuent104 Quote
It's extremely clear why someone would want one, to me: it offers the ability use medium format image characteristics on smaller, cheaper camera bodies, with increased speed and resolution.
But aren't the equivalent lenses for full-frame already common and readily available? Medium format lenses are generally not as high resolving as full-frame and not as fast either. So you'd hopefully get that promised sharpness and speed boost, but you'd end up with a lens you probably already had for that system. What am I missing? (What would be the killer combo that you couldn't get otherwise with a native full-frame lens?)
01-11-2016, 09:48 PM   #11
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QuoteOriginally posted by Adam Quote
A K mount or M42 to Sony E mount is the closest you're going to get, I think, as far as speed boosting Pentax lenses goes. They work nicely with the Sony A7 if you want to play around!
I've recently seen some k to m4/3 focal reducers also. They don't clearly specify if FF image circle is a requirement but that is my assumption.
01-11-2016, 10:49 PM   #12
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Allow me to clear up some facts; You CAN make a Pentax K to Pentax K Focal Length Reducer.

The Issue is that Kodak owns the patents. And the designs are sorta volatile; When properly matched to a lens, they increase resolution and improve image quality, but... You need multiple designs, because the wide converter is sensitive to the lens's exit pupil location, the rear element location, and the rear element size. You'd end up with a few very nice matched versions though.

Possible, yes. Rewarding, yes.

Easy to do right now? Not at all. I'm sure with enough time and effort one could build some, but Kodak has a very very strong patent on the designs, and I'm pretty sure their lawyers would suck to deal with if you decided to sell some...


Here's the Patent and a Lens Diagram. Enjoy!

http://www.google.com/patents/US5499069
01-12-2016, 12:18 AM   #13
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The only focal length reducer that I know of that is commonly available for all cameras, is a Front mount focus reducer. I mainly see them on eBay but I know that B&H sell them as well, however I do not recommend using them. they are not a good choice for any autofocus lens that has a front element that moves. Just too much mass for the lens to function properly. and they possibly could damage your lens or at least shorten its life. although they do have their uses, in my opinion you're better off using the lens as it was designed, without a focus reducer/extender.


01-12-2016, 12:58 AM   #14
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Thanks for all replays, I didn`t realize that for such reducer to work the camera has to have different sensor distance than lens was designed for. That would explain why almost all adapters that I saw were for 4/3 cameras. But then again there is this Kodak patent that Mothballs pointed out. Too bad it will probably never see widespread adaption...
Front mounted adapter mentioned by promacjoe are nice to know about but that is not what I am looking for, I recently got a chance to shoot with Helios 40 and I was hoping to access the borders of the image circle where its “swirly” effect is most apparent.
I will have to save up for pentax full frame body then.

Last edited by raff89; 01-12-2016 at 02:41 AM.
01-12-2016, 06:24 AM   #15
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QuoteOriginally posted by raff89 Quote
Thanks for all replays, I didn`t realize that for such reducer to work the camera has to have different sensor distance than lens was designed for. That would explain why almost all adapters that I saw were for 4/3 cameras. But then again there is this Kodak patent that Mothballs pointed out. Too bad it will probably never see widespread adaption...
Front mounted adapter mentioned by promacjoe are nice to know about but that is not what I am looking for, I recently got a chance to shoot with Helios 40 and I was hoping to access the borders of the image circle where its “swirly” effect is most apparent.
I will have to save up for pentax full frame body then.
Kodak used to supply most full frame sensors. It makes a lot of sense as to why they never sold the compressor; it would make full frame less enticing.
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