Has anyone tried to change a Pentax mount to accept C/Y lens

[youngcoby]

As the title says: has anyone successfully changed/adjusted the Pentax mount for C/Y lenses?

There has been a topic on this issue here:
http://forum.mflenses.com/viewtopic.php?t=8203&view=next

and these links:
http://forum.hardware.fr/hfr/Photonumerique/Objectif/adaptation-objectifs-bagues-sujet_12101_10.htm (french)
http://forum.contax-club.org/viewtopic.php?t=12815&postdays=0&postorder=asc&start=0&sid=95719427c974e4fd251a985edae8e980

I'd like to try it myself, but would like to get some feedback before surgery

Filip

[ryan s]

If I ever come across a mount for $30 or less, I'm going to do it. I refuse to do it to my K10D's mount without a spare on hand in case I ever sell the camera or want to go back. I even considered picking up an old *ist dS (for the pentaprism viewfinder) and modding that one to keep the K10 unmodified.

No help, I know I'm right there with you, though...been wanting to do this since I saw that French forum thread...

[youngcoby]

Thanks for your answer.

Although it isn't the one I need, I feel better now that I'm not alone
I just bought a cheap film K-mount camera to try things out on that one. There will be probably differences in mount, but those cannot be too big I guess.

I only guess that, if I want to mount M42 lenses, these will focus beyond infinity.

Anyway, in the next weeks, I'll have something to do...

[RioRico]

I've worked the other way around, with a slightly surgical but non-destructive easy modification to C/Y and OM lenses to fit them to PK mounts. And I have documented that mod here a few times.

I recall a couple threads where folks modded a PK camera with a Nikon mount, and a Canon FF camera with a PK mount. Modding a PK camera with a C/Y or OM mount should not be impossible, but all aperture control will probably be lost. Because of the register difference between PK (45.46mm) and C/Y (45.5mm) (and 46mm for OM), you may need to grind away a sliver of the camera body or replacement mount, to thin them for infinity focus.

[youngcoby]

Thank you all for your input.

I just got an old broken camera, and will try to change the mount on this one before breaking my digital one.

I'll keep you informed.

Filip

[youngcoby]

A follow-up of my adventures:

I finally started working on my Pentax K200D. Removing 3 small parts of the mount, and removing a little lever of the M42 retaining ring. All the time trying to put a Yashica DSB 50 on it.

This one works, it fits and is held steady. The Zeiss zoom 40-80 is also quite a good fit. If I dremel out a small piece of the lens-mount, it could be stuck firmly to the body with the pin holding the lens.

BUT: all the rest of the Zeiss lenses won't mount. There is still something holding them from screwing them in, and I can't see what. AAAAHHHHH

[poilu]

thanks for keeping us informed!

[seppstefano]

Hi all,
first post here, so bear with me

Youngcowboy can you confirm you can focus to infinity with the C/Y lens on the modded K mount? As far as I read from the register values, the C/Y has a larger value (+0.04mm) , so it should focus without issues.

TIA,

Stefano

[youngcoby]

SeppStefano,

I'll check it later, but (without pictures taken), I looked through the viewfinder, and I had the impression that it focussed perfectly to infinity. I don't know however if the infinity beep on the camera is 100% accurate.

I noticed last night that, when mounting the lens, there is still a small gab between the camera mount and the lens mount. Time to get some pictures...

[seppstefano]

Thanks a lot,
I'd love to mount my zeiss glasses on a new dslr and would dream of a nice K5, my oldie 30d allowed the trick and I'm trying to be sure before switching to pentax.

Did you find what prevented to mount other zeiss glasses? I'm too addicted to my 2/100...

Stefano

[youngcoby]

Just came back from some shooting.

I'm disappointed by the results: they look or out of focus, or incredibly soft. I also noticed that the connection camera-lens was not as steady as I thought it would be.

My K200D just has the stock focusing screen, but all my shooting was for infinity, and it indicated when picture was in focus. This was always at the infinity mark on the lens.

As I went through the pictures, I decided to take some pictures with my Eos 10D, with a Katz-eye focusing screen. I haven't seen the pics in full screen yet (don't have the appropriate usb cable here), but on the cam screen, they looked better than on the cam screen of k200D.

I also noticed that the object was not at infinity.....

So I tried again on K200D, and here it focus confirmed again at infinity. It also looked sharp while focusing.

I'll have to check full screen images later from the Canon, but something weird is going on: Canon says object is not at infinity, and Pentax says object is at infinity.....

Anyway, I decided for myself to get the K200D again to it's original state. For conversion, I had to remove the M42 stopper, so at this moment, M42 lenses are not easy mountable anymore. For the lenses I want to keep, I'll go the Leitax-way, and change the mount from C/Y to K. In the long run, it will be easier. Unfortunately, only MM lenses are adaptable, not AE's.

I have spent too much time working on it, instead of taking pictures. And I still have to practice a lot....

[seppstefano]

Thanks for your feedback, youngcowboy.

I currently use my zeiss glasses (AE and MM) with a C/Y to EOS and had no issues on my 30d. But canon dslr are much worse than pentax, that's why I'm really intrigued by that option.

Sorry but do I understand well: camera beeped focus ok on infinity and you found out of focus pictures? Perhaps the lens wasn't sitting flat on the K-mount? If I get it good, theory says it should reach infinite because of register (it should go a slight "beyond" infinite, really).

Stefano

[youngcoby]

Seppstefano,

you got it right: it beeped for infinity focus, but the pictures didn't look very sharp. Comparing to the Canon pics, I would not say that they are out of focus, but I have seen sharper ones.

What puzzled me most is that, on Canon, the lens setting was not at infinity. On Pentax it was.

Maybe this is because of the small "gab" between the lens mount and the mount of the camera, I don't know.

Also I found out what caused the lens to be sometimes difficultly mounting on the camera. Under the metal mount on the camera, there is a very thin metal ring. On this ring, it has a flange (M42 stopper - which was dremeled off) and 3 bent flanges. These last 3 are meant to tighten the lens to the camera, I guess. These 3 metal flanges cause a difficult mounting, I found out.

Also, when trying to mount the M42 adapter, I noticed that this keeps turning around while turning in the lens. This is (off course - I could have known), because the M42-stopper has disappeared.

I have spent too much time in trying to change the mount, and I am not willing to change anything irreversible to my lenses, so I will just change my K200 back to it's original state, and forget about mounting CZ lenses.

Maybe I'll change the mount of them to K-mount through a Leitax conversion - I'll see.

Regards,
Filip

[seppstefano]

Thank you Filip,
I think i really have to buy a spare pentax dslr to see what is possible to do before messing with a K5 mount...

Another "mad" option I was thinking of is to adapt a C/Y lens mount on a Pentax body... It would be fine for me because I have no pentax AF lenses, only old glasses here

Stefano

[youngcoby]

That's what I did: I had a K5, and bought a second hand K200 for testing. I also have considered the option of changing the mount of the K200 with one from an old Yashica camera, but I think that is a more difficult way to achieve the mounting of CZ lenses to Pentax.

The camera mount ring has to have the exact size, the holes for the screws have to be an exact fit, etc.

I don't know what the best way is, but the easiest probably is to go the (expensive) Leitax route. It's a pity that you need MM lenses for this. And I have some AE lenses ....

[youngcoby]

Oops, double entry

[seppstefano]

Are you of course aware of: http://forum.contax-club.org/viewtopic.php?t=12815&postdays=0&postorder=asc&start=30

Aren't you? Because the author states that, in order to focus at infinity, he had to modify something else in order to mount all of his lenses.

Stefano

[youngcoby]

Stefano,
yep, I saw that link (see my first post in this topic). It was this that made me trying adapting the K mount. I am not willing to start dremelling down body parts etc.

I have tried the easy way, and I had focus infinity. I would have to further adjust the retainer ring underneath the camera mount, and here it stops for me. I cannot mount my takumars easily anymore, and that concludes this story for me.

I want to use my set of Takumars, and have another MF set with converted K-mounts (some Leica and maybe some Contax). Have been buying too many lenses, and not using them enough.

I am happy I tried it, but one has to admit sometimes being on the wrong track....

[seppstefano]

My fault Filip

Out of topic: I stared at your lens set and it is really gorgeous! Congrat!

Stefano

[youngcoby]

Hey Stefano,

thanks a lot. Although I only got them through browsing this forum so often. And instead of taking pictures, I found myself looking for info on lenses all the time, and looking on the famous auction site trying to buy them cheaply.

And to be honest, I got tired of that. I just made a decision of letting go quite a lot of them. I'll stick to Takumars (I love the feel of them), and some converted Leica's and CZ's. Although I'm not sure if I'll keep the CZ's. Conversion is not cheap, and I don't need 3 or 4 lenses in the same focal length.

As soon as weather is better, i'll start going out and take pictures (and find out how to post them here )

[seppstefano]

I see Filip,
my experience is somewhat similar, but my three lils help me shooting way more than ever!

A lens of mine which keeps impressing me is a K200/4. Mechanically is a pleasure, although I'd like to have a built-in lens hood. I have to compare it to the Tessar 200/3.5 and will let you know. I bet it'll be a hard match, anyway. Too bad it seems so error prone to adapt a K5 for this task.

What worries me more are those shortenings of lens screws (and the plastic part). If they don't match perfectly, I guess the lens risks to be not perfectly parallel to sensor plane.

Stefano