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C/Y to M42?
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PostPosted: Sat Jul 10, 2010 7:53 am    Post subject: C/Y to M42? Reply with quote
I gather it's possible to go the other way from M42 to C/Y at least there seem to be adapters made for that. But is it possible to do the reverse? I'm not talking about mounting either on a DSLR though that might come in time. I just want to know if I could possibly use my M42 Takumars on my Yashica FX-2 and/or conversely use my C/Y lenses on my SPII's?

I'd be utterly thrilled to be able to use the C/Y long lenses I have on my Pentax. I finally broke down and got the Yashica just because I had an almost pristine Vivitar C/Y 300MM and I had nothing remotely like that for my Spotties. I'm a big wild bird watcher and my area is just bird central. My 3 Takumars are great, but they simply don't have that kind of reach. So far I haven't found anything really comparable that I've been able to afford.

I see this around a lot:

http://www.buynowmobi.com/M42-Lens-to-Contax-Yashica-C-Y-Mount-Camera-Adapter-Silver

But nothing that looks like it can mount M42's on C/Y cameras. Can it be done? Info appreciated. I'm a real newbie when it comes to SLR lenses and adapters and such, thanks!


PostPosted: Sat Jul 10, 2010 9:14 am    Post subject: Reply with quote
Hello and welcome to the forum.

There are two things to consider about using different lens and camera mounts - the physical size of the mount and the register distance or back-focus, the dimension from the film/sensor surface to the lens focal point at infinity focus. If the register distance of a lens is less than the camera then it cannot be mounted close enough to the film and infinity focus cannot be achieved.

To answer your question, the register distances of Contax/Yashica lenses and M42 cameras are virtually indentical, so the lens would need to be mounted directly against the camera mount and the bayonet fitting would need to be inside the camera mount. This is not possible because the bayonet is larger than the thread-mount opening, so a lens with a C/Y mount cannot be used on an M42 camera. However it is possible the other way around. The adapter you found fits inside the bayonet mount of the C/Y camera and creates the threaded mount for M42 lenses, flush with the camera, which allows infinity focus.

Last edited by peterqd on Sun Jul 11, 2010 2:17 pm; edited 2 times in total


PostPosted: Sat Jul 10, 2010 9:14 am    Post subject: Reply with quote
M42 lenses can easily be mounted on C/Y cameras with the adapter in that link. It doesn't work the other way around I'm afraid - the CY lens mount is bigger than the M42 mount on the camera.


edit... posted same time as Peter...


PostPosted: Sat Jul 10, 2010 3:50 pm    Post subject: Reply with quote
Well, that helps at least that it can go one way. I can at least use my Takumar 105MM on my Yashica which is great because while I can cover that range with my zooms the Takumar is definitely superior and that's definitely my best lens. Glad to know that one actually works though.

Thanks!


PostPosted: Sat Jul 10, 2010 5:52 pm    Post subject: Reply with quote
Welcome magkelly!

Happy to see you treasure the Takumar 105, a great lens imho as well.


PostPosted: Sat Jul 10, 2010 10:17 pm    Post subject: Reply with quote
You can mount M42 lenses on CY bayonet cameras easily, and I do this regularly to mount my CZJ lenses and some older M42 Yashinons on my FX-3, and it preserves infinity focus. You can't do it the other way about, as the throat diameters are different : you can put the little cup inside the big cup, but you can't swap them and put the big cup inside the little cup.

The thing to watch out for is that some CY-M42 adapters have a rim that will engage the stop-down pin on auto M42 lenses, but others don't. This means that, if you have the latter type, you need an A-M switch on the M42 lens in order to stop down for metering and taking, else you're stuck with wide bore.

Some adapters come with a key that engages on two notches on opposite sides of the adapter's diameter. This allows you to unmount the adapter if the lens has unscrewed and left the adapter mounted on the body.


PostPosted: Sun Jul 11, 2010 6:17 am    Post subject: Reply with quote
It's my only really great lens to date and absolutely my favorite. Out of my cold dead hands, that's the only way anyone would get their hands on it! I do have a Takumar 50 and 55MM but that's it so far.

I <3 those Takumars!


siriusdogstar wrote:
Welcome magkelly!

Happy to see you treasure the Takumar 105, a great lens imho as well.


PostPosted: Sun Jul 11, 2010 6:19 am    Post subject: Reply with quote
Okay, just cause I don't want to make a bad mistake on which adapter, any suggestions? I've seen one on Amazon and quite a few on Ebay, so which one is the most reliable for these?


alex wrote:
You can mount M42 lenses on CY bayonet cameras easily, and I do this regularly to mount my CZJ lenses and some older M42 Yashinons on my FX-3, and it preserves infinity focus. You can't do it the other way about, as the throat diameters are different : you can put the little cup inside the big cup, but you can't swap them and put the big cup inside the little cup.

The thing to watch out for is that some CY-M42 adapters have a rim that will engage the stop-down pin on auto M42 lenses, but others don't. This means that, if you have the latter type, you need an A-M switch on the M42 lens in order to stop down for metering and taking, else you're stuck with wide bore.

Some adapters come with a key that engages on two notches on opposite sides of the adapter's diameter. This allows you to unmount the adapter if the lens has unscrewed and left the adapter mounted on the body.


PostPosted: Sun Jul 11, 2010 8:42 am    Post subject: Reply with quote
The three I have are marked Jolos, Kood, and 'PC Body Yashika [sic]'. All work well, though the Jolos seems a little better engineered than the other two.


PostPosted: Sun Jul 11, 2010 11:59 am    Post subject: Reply with quote
peterqd wrote:
This is not possible because the bayonet is larger than the thread-mount opening, so a lens with a C/Y mount cannot be used on an M42 camera.


Well, it is possible by replacing the bayonet on the lens with an M42 mount. =)


PostPosted: Sun Jul 11, 2010 2:23 pm    Post subject: Reply with quote
Arkku wrote:
peterqd wrote:
This is not possible because the bayonet is larger than the thread-mount opening, so a lens with a C/Y mount cannot be used on an M42 camera.


Well, it is possible by replacing the bayonet on the lens with an M42 mount. =)


But then it isn't a lens with a C/Y mount is it? Rolling Eyes
Why do you always disagree with everything? I don't think I've ever seen you agree with something I've said.


PostPosted: Sun Jul 11, 2010 3:53 pm    Post subject: Reply with quote
peterqd wrote:

But then it isn't a lens with a C/Y mount is it? :roll:


Depends on how you define a C/Y mount lens. Potentially annoying speculation follows:

• If you put a C/Y to EF adapter on a C/Y mount lens, does it become an EF-mount lens? Furthermore, does it lose it's C/Y-mount property? If would argue that the answer to both is “no”, but especially the former point could be contested on basis that the lens + adapter combo is not fundamentally different from a lens that just happens to have a weird way of attaching the final mount. (For example, some might argue that Adaptall-2 lens + mount combos are “native” lenses for the target mount even though they do have an adapter. Yet most would also agree that they are still Adaptall-2 mount lenses.)

• If you take off the C/Y mount from a C/Y mount lens and replace it with an M42 mount, does it become an M42 mount lens? Furthermore, does it lose it's C/Y-mount property? I don't think there is a clear answer to either and it depends entirely on the perspective: for the purposes of someone looking to use C/Y mount lenses on M42 cameras (or with an M42 adapter) it matters that the original mount was C/Y. Meanwhile for someone with a C/Y camera this particular copy of this lens is no longer a C/Y mount lens but “the lens” in general is one they might consider, and for someone with an M42 camera even though this particular copy could be used on their camera, “the lens” in general might not be one they would consider an M42 mount lens. Thus, from a practical point of view, I would say that for me a converted C/Y mount lens is still a C/Y mount lens and the mount conversion is just a slightly more complicated means of attaching an adapter that happens to involve the, reversible and possibly temporary, removal of the original mount.

peterqd wrote:

Why do you always disagree with everything? I don't think I've ever seen you agree with something I've said.


If I fully agree with something and consider the answer exhaustive, why would I post a message saying “I agree.”? Doing so adds no additional information, just bumps the thread unnecessarily (i.e. creates annoying noise).

Meanwhile, e.g. in this case I don't see myself as disagreeing with anything you said; I just remarked that using C/Y on M42 is not impossible if you are willing to go outside the realm of “ordinary” adapters. I even put a smiley after the remark in acknowledgement that for most people this is not a very “serious” option.

The reason I made this remark in the first place is that I misinterpreted the topic of the thread as a question about C/Y on M42, not the other way around, and I thought it would be better for future reference if this thread also contained the answer to that question. I would've posted the same thing you said about the impossibility of C/Y to M42 adapters but I noticed that it was already here, and so I just quoted your post to add this mention of the possibility of mount conversion.

(And, to be honest, I didn't even look who had posted the original message, nor do I recall ever disagreeing with you about anything in the past. Sorry if you feel insulted, but you can rest assured that it's not personal.)
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