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06-24-2009, 02:22 AM   #1
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The impossible lens club?!

I thought first that I should include this in the "off brand club", but then it appears that the lenses there are mostly lenses that does really mount on K or M42 cameras, focus to infinity etc. So maybe we are ready for a club for lenses that should not work on a Pentax camera?

I have a history with Konica before I went for Pentax, and I still have a soft spot for Konica Hexanon lenses. Today they are dead lenses, since they don't mount on any digital camera without mechanical hacking. And I'm not prepared to trash my fine Hexanons since I still occasionally use them on a Konica T3.

Of course, I have not been able to resist to try to mount them on a Pentax DSLR. There are two problems with this:
1) The bayonett does not fit. However, some Hexanon lenses can with some trial and error mount a little bit on a K-mount. The connection is less solid than the Nikkor lenses, where some also mount (almost) on K mounts.
2) Konica have about 5mm shorter registration distance than Pentax and was one of the shortest SLR registration distances. This combined with that Minolta bought Konica, promissed to carry on the AR mount, gave it up and stopped all use of the AR mount, and then sold out from camera production themself, is why I call these lenses dead in the digital age.

There are primarily two lenses I'd like to be able to use on a Pentax DSLR:

1) Hexanon AR 85mm f1.8. A very nice portrait lens.

2) Hexanon AR 55mm f3.5 macro. A very sharp macro normal comparable to the micro-Nikkors. It reach 1:1 with an automatic tube that was sold together with the lens. My plan is to hack two third party tubes, a Pentax and a Konica, and get a mount with a K mount on the camera side and an AR mount on the lens side. I will lose apperture connection, but should be able to work quite well in M mode. The fact that the macro Hexanon have the same functionality as some micro-Nikkors, with an apperture opening that automatically compensate for the changing lens speed with changin magnification should help.

But first the 85mm. It mounts on the K20D, but I dare not let go of the lens. I loose inifity. In fact, I cannot focus beyond about 2m. But portraits can be taken within 2m distance:







06-24-2009, 03:21 AM - 1 Like   #2
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Hi Douglas,
I think there are some folks on this forum who do tinker some of those impossibles. Not to mention the Nikon-on-Pentax thread. This
could be real fun and a learning experience as well I hope.

Here's one of those dumb-but-I-tried-it impossibles:


This lens is from a russian night vision device. It has an M42x1 mount (read: "Pentax screw mount"), but the rear elements are protuding
waaay deep behind the mount. So here's my "I-tried-something" solution: Just remove the whole rear lens group !

Half a lens and it has no aperture but you are getting infinity (on K100D, here's more pics)

Mmmmh, another 'interesting' lens. There is the same lens (nearly) from the same night vision device which does not protude so much
behind the mount, seems to be a collectible right now (prices are rocketing up). For sure, you'll never get accurate colors from such a night
lens, but CA from hell .-) Please search on the forum.manualfocus.org for more (a good resource for any tinkerer)
Keep them coming,
Georg (the other)

Last edited by georgweb; 06-24-2009 at 03:38 AM.
06-24-2009, 04:24 AM   #3
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That's a cool lens. Gives sort of dreamy effect. I like the goat in your link.
I think Nikon barely count in this thread since they have about the same registration distance as Pentax and many of them actually mount.

Low Level of impossibility:
Large format lenses with large registration distances that leaves plenty of room for adapters (and for many their are official or 3rd party adapters to buy prefabricated), such as Mamiya (105mm), Rolleiflex (102.8mm), Bronica (101.7mm), Pentax 67 (84.95mm), Hasselblad (74.9mm), Pentacon six (74.1mm), Pentax 645 (70.87mm), Mamya 645 (63.3mm).
Some adaptor 35mm systems with large registration distance: T/T2/TX/T4 mounts (55mm). All adapters available used, at least T2 new. No sport. Adaptamatic, adaptall-1 and adaptall-2 counts here of coure.

Medium difficulty:
35mm lenses from systems so close to the Pentax K/m42 registration distance (45.5mm), that it is difficult to make an adapter: Contax (48mm), Leica R (47mm), Olympus OM (46.5), Yashica (45.5), Praktica (45.5mm) and more. All these will focus to infinity or a little bit beyond (but who cares). As long as you can squeze them into the K mount. Nikon-F (46.5mm) would belong to this group, would it not be for the lucky accident (is it?) that at least older F mounts will fit on K mount cameras, but not all lock (see the Nikon on Pentax thread).

Really difficult:
35mm cameras with registration distances shorter than the K/m42 distance: Exakta, Topcon (44.7mm...I've been drolling over some lenses, the common ones does not go for much), Rolleiflex (44.6mm), Minolta/Sony (44.5mm), Sigma (44mm), Canon EF (44mm), Minolta SR (43.5mm), Canon FD/FL (42mm), Konica AR and Konica F (40.7mm), Olympus E etc (38.67mm), Contax G (29mm), Olymous Pen (28.95mm), Leica M39 (28.8mm), Leica M bayonet (27.8mm), and more. With my Konica AR test, it appears that focus is very limited already at a 5mm flange difference. So somewhere soon below 40mm, there wont be any correct focus at all, and hacking will be necessary.
More possible lenses with great level of difficulty would be 16mm film (23.22mm), C mount (17.526mm, surveilance cameras for example), CS mount (12.52mm), D mount (12.29mm).
Then there is the added complexivity that Georg discovered in his hack: if the lens is built for something that does not have a mirror, the final lens may extend well into the mirror-box. Or the diameter of the mount may be wider on the lens than on the K mount.

So who wants to score high on the difficulty level?




QuoteOriginally posted by georgweb Quote
Hi Douglas,
I think there are some folks on this forum who do tinker some of those impossibles. Not to mention the Nikon-on-Pentax thread. This
could be real fun and a learning experience as well I hope.

Here's one of those dumb-but-I-tried-it impossibles:


This lens is from a russian night vision device. It has an M42x1 mount (read: "Pentax screw mount"), but the rear elements are protuding
waaay deep behind the mount. So here's my "I-tried-something" solution: Just remove the whole rear lens group !

Half a lens and it has no aperture but you are getting infinity (on K100D, here's more pics)

Mmmmh, another 'interesting' lens. There is the same lens (nearly) from the same night vision device which does not protude so much
behind the mount, seems to be a collectible right now (prices are rocketing up). For sure, you'll never get accurate colors from such a night
lens, but CA from hell .-) Please search on the forum.manualfocus.org for more (a good resource for any tinkerer)
Keep them coming,
Georg (the other)
06-24-2009, 05:22 AM   #4
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Impossible?

Use Leica M and Alpa lenses in M42 bodies.

06-24-2009, 06:30 AM - 1 Like   #5
Zav
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A friend of mine have this:


He had to send it to China in order to have it modified for Pentax, more details in chinese there:
Carl Zeiss 35mm f1.4 HFT Rollei QBM Y Pentax K

And here is a sample of the thing:

Last edited by Zav; 06-24-2009 at 11:41 PM.
06-24-2009, 06:46 AM   #6
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Interesting stuff - leaving aside MF/LF lenses adapted via bellows or tubes - there's quite a bit that can be lashed on a K mount.

I did the Konica thing as well - Konica mount Vivitar 3.5/200mm on the K100D



The same deal, this was about as far as the thing focused.
06-24-2009, 06:53 AM - 1 Like   #7
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Has anyone considered taking a really cheap, worn out pentax digital body and simply removing the mirror? That way you could use lenses with elements that extend into the camera. Metering would have to be all-manual, the viewfinder would be useless, and you'd have to work things by trial-and-error checking shots on the rear LCD, but it could be interesting. Too bad all the live view models are still too fresh.
06-24-2009, 01:21 PM   #8
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QuoteOriginally posted by er1kksen Quote
Has anyone considered taking a really cheap, worn out pentax digital body and simply removing the mirror? That way you could use lenses with elements that extend into the camera. Metering would have to be all-manual, the viewfinder would be useless, and you'd have to work things by trial-and-error checking shots on the rear LCD, but it could be interesting. Too bad all the live view models are still too fresh.
Well, I have thought of it, but my *istDS is meant to be converted for IR some day. It would be much better of course to use a model with liveview, and then it will cost some more. (Now someone will tell me to buy that EVIL Samsung...and then I ned to tell again that we do know nothing about what lenses we can mount on it)

Has anyone tried to shoot through a projector lens, movie camera lens etc?


Last edited by Douglas_of_Sweden; 06-24-2009 at 01:31 PM. Reason: mix of Swedish and English (ush!)
06-24-2009, 01:53 PM   #9
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I stuck a Schneider Componon enlarger lens on, but as it's 35mm (I have it from my 1/2 frame days) about the only thing it did was extreme close ups. People have got excellent results using 105-135-180mm enlarger lenses.

Currently I'm working on a 75mm view-rokunar f/3.2, but can't get infinity - bellows is too long, and the tubes also (which is strange: 75mm - 45.46 register = 29.54mm so I thought I could get reasonably long focus... have managed maybe 2 feet so far.)
06-24-2009, 11:11 PM   #10
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QuoteOriginally posted by Nesster Quote
I stuck a Schneider Componon enlarger lens on, but as it's 35mm (I have it from my 1/2 frame days) about the only thing it did was extreme close ups. People have got excellent results using 105-135-180mm enlarger lenses.

Currently I'm working on a 75mm view-rokunar f/3.2, but can't get infinity - bellows is too long, and the tubes also (which is strange: 75mm - 45.46 register = 29.54mm so I thought I could get reasonably long focus... have managed maybe 2 feet so far.)
That's odd! Hope you succeed, and hope you will post some results here!
06-25-2009, 05:09 AM   #11
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If this thread is about non M42/K so it is about my Leitz 560/6.8 I bought it with Novoflex gear and Nikon mount. I converted mount to M42 and now can use it with my K20D. I don't have infinity - it can focus up to 100-150 meters.



here is my thread https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/59870-leitz-56...mpression.html
06-25-2009, 05:36 AM   #12
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An impossible lens shooter could use a short extension tube to move a lens away from the mirror provided the tube has not internal structure that interferes with the rear element of the lens. You still lose infinity but it'd be a clean installation. Used M42 tubes, well, they're not expensive.
06-25-2009, 05:58 AM - 1 Like   #13
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QuoteOriginally posted by Piotr Quote
If this thread is about non M42/K so it is about my Leitz 560/6.8 I bought it with Novoflex gear and Nikon mount. I converted mount to M42 and now can use it with my K20D. I don't have infinity - it can focus up to 100-150 meters.



here is my thread https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/59870-leitz-56...mpression.html
at 150 meters your 5 inch high little bird that you are shooting, is only 3% of the screen height, so I don;t think you rloss of focus at infinity is too critical
06-25-2009, 07:16 AM   #14
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That's not a lens it's a weapon
You can of course use it zone focused with a KX or Yashica Electro X, both of which have mirror lock up.
06-25-2009, 07:17 AM   #15
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In the spirit of things, here are two shots with a K100D. One of them is with a Micro Nikkor 55mm 3.5 wide open. The other is the View-Rokkor 75mm 3.2 closed down a smidge, mounted in an extension tube. Which is which?




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