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12-21-2010, 03:09 AM - 1 Like   #106
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Non-expert tinkerer here, just a Dremel-wielding menace. Sorry I ignored this thread for so long. At the start, Douglas suggested levels of difficulty in lens adaptation. In the most difficult class was Exakta (44.7mm) mount to PK (45.46mm). I documented a simple conversion here: ANNOUNCING: Easy cheap non-destructive Exakta-Pentax adapter where instead of chopping the lens, I grind down a generic M42-PK adapter. When I brought this up here: EXAKTA TO PENTAX ADAPTER member chse said that many Exakta lenses can be fitted with a simple T2-PK adapter. But he didn't say which lenses... ;(

Since Topcon has the same register as Exakta, the same grind-the-adapter trick might work. But I have no Topcon lenses around to experiment upon, so I dunno.

In Douglas's taxonomy, the medium difficulty class includes OM (46.5) and C/Y (45.5). I find both of these very simple -- just use a Dremel to taper the lens bayonet flags to fit under the PK mount lugs. Praktica has the same register as C/Y, but I also have no Praktica lenses to put under the knife. Should I go out of my way to look for cheap Topcon and Praktica bayonet lenses?

Most of the lenses I tinker with aren't impossible, just strange. The hugest I've dealt with is an old Gundlach Turner-Reich Anastigmat 300/7 LF beast weighing 910g including shutter-iris assembly. Every now and then I'll put it on 300mm of tube+bellows extension, weighing another 700g. And the mount is held together with... electrical tape. Hey, it works! But not real well, since the rear element is damaged a bit. Ah well, the lens only cost US$7.

As tinkerers here know, M42 and PK macro tubes and bellows, and M39-M42 and all sorts of M42-PK adapters, are our friends. So are PK body caps. Many enlarger lenses are M39; many aren't. I have a couple with 29mm threads. And projector lenses may have odd mounts. So I can order (and wait for) step/adapter rings, or I can poke a hole in a body cap and shove the lens onto the PK bellows. And some projector lenses merely need a PK macro tube-set taped around the body to provide a PK mount. I have four sets each of PK and M42 tubes -- just barely enough.

In the almost impossible category are very short-register lenses like those on C-mounts. Ah, but I have converted a Pentax/Cosmicar 50/1.7 CCTV lens to PK! Just fit it into a body cap! Unfortunately, I screwed up the focus whilst diddling with it, so now it's a fixed-focus macro lens with a working distance of about 50mm. Ah yes, just what I need: Yet Another Macro Lens (YAML). I'm afraid that CCTV-cine-spy-16mm lenses will await an m4/3 or NEX camera, or maybe I'll try to hack a fixed-lens P&S to take such glass. I have this hot little one-buck Bell & Howell Filmovara 15-25/1.2 that I'm dying to try...

12-21-2010, 03:52 AM   #107
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Another Dremel Novice here

After about ten months of a growing LHA (Lens Hacking Addiction) I have a growing pile of broken lenses to prove it....
I also have a couple of working and a lot of experience

I have, as MattGun and others been trying to convert lenses to PK/A with no real success.
I did manage to get a Topcor (Exakta) 35mm f2.8 to work as a PK mount but I later managed to break one of the aparture blades little pins so now that lense is looking at me with a very angry "eye"

I now have a very nice Mamiyar Sekor SX 55mm 1.7 that I would like to change to PK Mount but the copy I have is pretty minty so I want to do this without damaging the lens but Im not sure that works.
The Sekor SX lenses has a little ridge around the m42 mount that prevents them from screwing on correctly onto a Pentax + a little pin that will get trapped in any deeper areas, like screws or the AF hole on the Camera mount locking the lens to the camera.
If you have an SX lens. DONT try to screw it on

Has anyone managed to adjust infinity on an SX lens?
12-22-2010, 02:08 PM - 1 Like   #108
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Time to update this list. Mainly because more and more commercial conversion kits and adapters are available. Below is the original one. This is how I would now rate it.

Low Level of impossibility (=easy):
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.

In this category we should include some originally medium to really difficult mounts that has become simpler due to ready commercial adapters and exchange mounts.

Exchange mounts from Leitax:
Leica R (47mm)
Olympus OM (46.5)

Exchange mounts:
Topcon (44.7mm)...it appears to me that this works only because the original Topcor mount was very thick, so by replacing it with a thinner mount, one can get the right registration distance to Pentax...Exakta is the same mount, but I don't think exakta lens mount pieces are thick enough(?)

Optical adapters:
Minolta SR (43.5mm)
Canon FD/FL (42mm)
Nikon-F (46.5mm)

All these are still more difficult if you want to do it yourself without having to use a degreading optical adapter.

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), 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.

Really difficult:
35mm cameras with registration distances shorter than the K/m42 distance: Exakta, Rolleiflex (44.6mm), Minolta/Sony (44.5mm), Sigma (44mm), Canon EF (44mm), 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.

QuoteOriginally posted by Douglas_of_Sweden Quote
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.

*Rolleiflex: Commercial conversion available, you have to send in the lens.

Another way to express these difficulty levels are
1) You have to build an adapter
2) You have to hack the mount
3) You have to hack more than the mount (apperture ring etc)
12-22-2010, 08:26 PM   #109
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My only quibble with your excellent list is that Exakta-to-PK should be Easy or Moderate, not Most Difficult. I've shown that such an adaptation is simple and non-destructive. Remove the index screw from the lens; glue on an M39-M42 adapter ring; grind ~0.6-0.8mm from the flange of a Bower-type M42-PK adapter ring (I used sandpaper); screw the Bower-adapter tightly onto the M39 ring; and VOILA!

12-22-2010, 11:57 PM   #110
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I'm really looking forward to trying out your conversion RioRico. It seems quite simple. I just need to get my hands on some junker Exakta lenses.

Regarding the conversion difficulties:
I've converted two Canon FD lenses and the quite big register distance difference to PK/M42 can be dealt with if you're willing to go for irreversible conversion. The FD breechlock mechanism is so thick that once you remove it completely you're pretty close to the PK register distance. On some lenses a reversible conversion might be possible by just carefully dismantling the mount but the breechlock is such a complex mechanism that removing it piece by piece and rebuilding it later (to return the lens to it's original form) would be a very difficult and time consuming task.

edit: Here's two pics demonstrating the the thickness of the breechlock:
breechlock intact

same lens with breechlock removed and M42 mount (taken from an old lens) attached:



... but getting the register distance right is not all there is to FD->PK conversion. Once you remove the breechlock you'll notice that the aperture ring doesn't control the aperture anymore. I've concluded that the FD aperture control works something like this:

aperture ring->breechlock(->camera body)->aperture blades

so once the breechlock is removed the linkage is broken and you'll have to device a new way of moving the aperture blades. It can be done or you can use the lens only wide open if the lens is up to it (like a 2.8/300mm L).

I believe that with older FL lenses (same reg dist) the aperture mechanism is of the "traditional" preset type so converting them with aperture control intact should be possible (haven't done it though, so I'm not sure)

so in a nutshell:
- be sure you're OK with hacking the lens irreversibly (I wouldn't do it to a rare mint condition lens of any mount)
- take out the breechlock and all it's parts (a few small screwdrivers may be enough or a dremel may be needed) This may need disassembling the whole lens.
- check the register distance (should be close to PK now, shave something if needed)
- attach a flanged M42->PK adapter with a 3-5 screws to existing screwholes
- go shoot. Only wide open with FD or with preset stopdown with FL (maybe?)

Here's once again the thread on how I converted a Vivitar Close Focus 2/28mm from FD to M42. Still working btw. Shot this yesterday with it:


Last edited by ovim; 12-23-2010 at 12:12 AM. Reason: added two pics
12-23-2010, 12:51 PM   #111
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Of course there's a simplest conversion that makes any short-register lens a close-focus PK gem: Buy cheap macro-tube sets for the bases involved. I have Nikon and Minolta glass now, so I just ordered one set each for those. I can mod C/Y and OM bases, so I don't need sets for those. I've already sold all my C/FD glass, so I don't need a set for that either, not unless I fall into something ultra-cheap that fills a hole in my lineup. Was there a C/FD 300/2.8?

All those macro-tube sets use the same 60mm-thread modular tubes and adapters, easy to interchange -- but with the loss of ~12mm. Let's get close... Hey, who needs infinity? Infinity just means, too far to measure, just as infinite means, too many to count. But I digress...

As mentioned, I have Minolta glass -- much is great stuff but I can't use it and it's not worth selling right now. I bought one cheap junker, a Gefitex Auto Zoom 85-210/4.5 for five bucks (shipped) for the purpose of developing a PK conversion. Like your C/FD, ovim, it has a thick mount plate; my measurement showed that it could be replaced with a flanged M42-PK adapter at about PK register distance. So I removed the three screws, and carefully pulled the mount, and peered inside, and tried to replace it -- but now the aperture won't engage. Damn. Another lens fit only for burning ants. Fix it till it's broke, that's my specialty.
12-23-2010, 01:52 PM   #112
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QuoteOriginally posted by RioRico Quote
Was there a C/FD 300/2.8?
Sure there was.

It's my second conversion. Now with a K-mount and even with a working aperture lever.

02-06-2011, 08:39 PM   #113
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ovim, what about Canon FD 200mm F2.8, like this one:
CANON FD 200MM F2.8 FAST CANON CAMERA TELEPHOTO LENS - eBay (item 170592503510 end time Feb-17-11 15:10:26 PST)

is removing breechlock possible here as described above? (I have no experience with Canon mount at all)

And by the way - I just love this thread.
02-06-2011, 10:09 PM   #114
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QuoteOriginally posted by Cypis aka Piotr Quote
ovim, what about Canon FD 200mm F2.8, like this one:
CANON FD 200MM F2.8 FAST CANON CAMERA TELEPHOTO LENS - eBay (item 170592503510 end time Feb-17-11 15:10:26 PST)

is removing breechlock possible here as described above? (I have no experience with Canon mount at all)

And by the way - I just love this thread.
I see no reason to buy that 200 f2.8. They have it high for the age and mount type when there are nice M42 200's out there for about the same or somewhat more that you can just mount up with a M42 to K converter. If I remember right I have several older 200 that are around that speed already in M42 or K mount that I don't use much anymore. These are "3rd party" lenses but they were a fraction of that one and turn out great photos. Having to convert the Canon after purchase could be a long process and might not be the most efficient use of resources I can share the brand names if you wish so you can look for one of them. PM me if you wish,
Alan W.
02-06-2011, 10:59 PM   #115
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kacansas03, I'd agree with you had I a single fast (like 1:2,8) prime 200mm around.
And the cheapest ones I found were Canon FD...
If you have anything comparable - just let me know, I'd love to try it.
02-07-2011, 06:19 AM   #116
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Spurred by discussion with RioRico in the other thread here's another 'no sport' which was done out of frustation from a medium-high non-success.

02-07-2011, 06:36 AM   #117
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Interesting, Georg! Any samples to share? I like to use older and older lenses... This time a small and unmarked Petzval-type lens (c. 1880's).



And this combination yielded this result (after some PP; I tried to create a "digital Ambrotype"):


Last edited by Asahiflex; 02-07-2011 at 07:08 AM.
02-07-2011, 07:19 AM   #118
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Very nice result Asahiflex !
Touching portrait with a haunting feeling.

The area from the nose to the right cheek looks off though. Is that an artifact from the lens or something else?
02-07-2011, 07:40 AM   #119
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QuoteOriginally posted by aliasant Quote
Very nice result Asahiflex !
Touching portrait with a haunting feeling.
Thanks! That was what I was after.

QuoteQuote:
The area from the nose to the right cheek looks off though. Is that an artifact from the lens or something else?
No; it's what you get when you don't have a perfect skin. The PP made this all the more apparent.
02-07-2011, 10:37 AM   #120
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Moderately difficult lenses

For the past few months I've been playing with my tilt/shift macro bellows (the Kopil Bellowsmat) and have come up with a system for mounting and focusing enlarger lenses. Because my best film roll ever shot came from a Retina Reflex I've limited myself to using only Schneider lenses with this system; the collection currently includes the following:
1951 Componar 50/3.5 (macro only)
1960 Componar 75/4.5 (macro only)
1939 Componar 13.5cm/4.5 (infinity focus)
late 1920's Tele-Xenar 30cm/5.5 (not yet mounted)

Conversions of these lenses is relatively easy; I purchase t-mount adapters and metal body covers for m42, cut to fit the backs of the lenses, and drill/tap some tiny screws to fix them in place. These lenses all have apertures, usually with 15 or more blades, so that's my DOF adjustment. Focus comes from moving the bellows back and forth; time consuming when going from macro to landscape but never more than about 5 seconds.

Here's the 13.5cm mounted and some test shots from yesterday:


Tilt test, dead branches:


Bokah test:


And, finally, a portrait test:


Notes of interest with this system:
- Some older 50mm Componars have a removable base that unscrews. This could potentially be mounted without a bellows and using the base screw to focus. I almost had this working with my copy but, when modifying the old base, I accidentally overtightened the lathe chuck, preventing smooth rotation (it's pretty much jammed in place and macro only now).
- The 30cm is sitting on my desk at work waiting for me to make some sort of adapter to fit its mounting thread. I was unable to find off-the-shelf rings that would fit so I'm resorting to measuring and cutting matched threads at work. A pain, but I suspect it will be well worth the trouble.
- The 13.5cm focuses well beyond infinity even with the bellows, which adds about an inch. I am watching for $10-ish auctions for 105mm and 90mm versions to determine what the limit is for these bellows. For now, I'm very happy with the results of the 13.5.
- The componars were the cheaper of the 2 enlarger types manufactured by Schneider. If I see any Componons at bargain prices I'll try to do a comparison of the 2 lines. I don't see any problems with the componars if those are all that fit your budget; these are very capable lenses considering that they go for around $10-$20.
- The bellows ran me about $90, but none of these lenses cost me more than $20 ($25 if you add the adapters).

If anyone sees a better fit for these lenses let me know; they're certainly not "impossible" and, from experimenting, I don't want to put them with "macro" because they have potential for more when properly mounted. Definitely wanted to post them somewhere, though, as I feel it's a good system and recommend it for others.
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