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?
Originally posted by georgweb 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)