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04-17-2008, 10:29 AM   #1
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C mount adapter?

Hey guys, I just found a bunch of old c mount lenses theat are no longer needed at work (Schneider 1:1.4/16 not sure of the focal range). I'm curious if anyone has any experience mounting them to a Pentax DSLR. I thought it might be fun to see what I can do with these guys. I think I've found an adapter ring to go from c mount to K mount. Also, would I be able to go from C mount to M42 to K or is that just too much adapting (This would probably be a cheaper idea). Any thoughts?


Last edited by Ecosse; 04-17-2008 at 11:08 AM.
04-17-2008, 10:37 AM   #2
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Are your c mount lenses Canon 35mm lenses? If so they won't mount on the Pentax. The adapters are probably the reverse - Pentax on Canon. The problem is the Pentax has a longer mount to film distance than the Canon. I would worry about my mirror if the rear of the lens were closer because of a sunken adapter.
04-17-2008, 10:39 AM   #3
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QuoteOriginally posted by Canada_Rockies Quote
Are your c mount lenses Canon 35mm lenses? If so they won't mount on the Pentax. The adapters are probably the reverse - Pentax on Canon. The problem is the Pentax has a longer mount to film distance than the Canon. I would worry about my mirror if the rear of the lens were closer because of a sunken adapter.
C mount - Wikipedia, the free encyclopedia
04-17-2008, 10:44 AM   #4
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I've actully looked this kind of thing up. The C-mount distance is much closer than the K mount or the m-42 mount -- or any SLR mount for that matter.

I've seen adapters for the opposite, like mounting a pentax lens on a C-Mount Camera -- but not the reverse.

For example:
General Brand | C-Mount Adapter for Pentax Universal (M42) Lens

I've toyed with the idea of messing with them on webcam sensors, as there are some really really fast C-Mount lenses.

04-17-2008, 10:44 AM   #5
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Thanks for the clarification. The WIKI article does not give the lens to film distance This is the critical problem. If the lens to film distance is less than that of the Pentax mount, you have a problem that cannot be resolved without the possibility of damage to our mirror assembly. I note, that some of the lenses have protruding rear elements that would make the problem even worse.

If the rear offset is OK, then a combination of adapters just might work for you.

I aplogize for not understanding C-mount.

EDIT: I see that the problem I was suggesting you look for is a fact in the prevous post.

Last edited by Canada_Rockies; 04-17-2008 at 10:46 AM. Reason: Added ref to next previous post
04-17-2008, 11:04 AM   #6
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QuoteOriginally posted by Canada_Rockies Quote
Thanks for the clarification. The WIKI article does not give the lens to film distance This is the critical problem. If the lens to film distance is less than that of the Pentax mount, you have a problem that cannot be resolved without the possibility of damage to our mirror assembly. I note, that some of the lenses have protruding rear elements that would make the problem even worse.

If the rear offset is OK, then a combination of adapters just might work for you.

I aplogize for not understanding C-mount.

EDIT: I see that the problem I was suggesting you look for is a fact in the prevous post.
Scroll down a bit to get to a chart of flange distances:

Lens mount - Wikipedia, the free encyclopedia

Kinda interesting stuff.
04-17-2008, 11:14 AM   #7
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Thanks for the info guys. Anyone know any other interesting uses for lenses like these? Maybe I'll just throw them up on ebay and see what I can get.
04-17-2008, 03:16 PM   #8
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QuoteOriginally posted by Ecosse Quote
Thanks for the info guys. Anyone know any other interesting uses for lenses like these? Maybe I'll just throw them up on ebay and see what I can get.
I know you can use them as some sort of close up lenses, imagine attaching a normal pentax k mount lens to an extension tube this has the same effect, you loose infinity but you get close focus which might be vey useful for macro like photos. I believe these lenses will have very beautiful rendering and bokeh.

Actually I orderered CANON TV ZOOM LENS J6X12 12.5-75MM 1:1.8 for 10 dollars from ebay.



Cheers,

Voe

04-17-2008, 05:06 PM   #9
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THanks Voe, I'm just curious as to how I actually mount it to the camera.
04-17-2008, 05:35 PM   #10
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QuoteOriginally posted by Ecosse Quote
Hey guys, I just found a bunch of old c mount lenses theat are no longer needed at work (Schneider 1:1.4/16 not sure of the focal range). I'm curious if anyone has any experience mounting them to a Pentax DSLR. I thought it might be fun to see what I can do with these guys. I think I've found an adapter ring to go from c mount to K mount. Also, would I be able to go from C mount to M42 to K or is that just too much adapting (This would probably be a cheaper idea). Any thoughts?
The lens could be mounted on the Pentax DSLR with little trouble,but the registration distance at infinity is about 17mm. The Pentax K-mount is 45.5mm which is almost three times the distance. It would only focus at close range. This mounting would give a larger image circle then normal for this lens. The normal image circle would vignet greatly. They may make good macro lenses on a bellows, since the image circle is expanded and infinity isn't normally a concern. I thought about using non 35mm lenses,but looked at lenses for camers with a larger format to allow for the adapter, while providing infinity focusing. The trouble with that is that they are to big and heavy. They aren't cheap either.

Dave
04-18-2008, 08:35 AM   #11
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QuoteOriginally posted by Ecosse Quote
THanks Voe, I'm just curious as to how I actually mount it to the camera.
I plan to workout something using spare parts of other lenses and whatever I can tweak, but there is also an adapter to M42 mount at:
Borg C-Mount to M42 AD Adapter
I don't plan to invest to much in this lens as bought it only for experiment


Cheers,

Voe
02-27-2009, 11:03 PM   #12
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Just to dredge up an old thread, how did the experiment go Voe?
A friend has a Canon lens he wants to get rid of and I'm exploring what options I'd have to adapt it to my K20D. From what I've read here it's shimming the lense out to reduce the degree to which the lens would penetrate the K20D body possibly by butchering either a macro tube or tele converter so you have a female Canon mount to male Pentax K mount.
05-03-2009, 11:12 AM   #13
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QuoteOriginally posted by xjjohnno Quote
A friend has a Canon lens he wants to get rid of and I'm exploring what options I'd have to adapt it to my K20D.
The C-mount referred to here is about CCTV cameras and lenses, not Canon.
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/58553-lens-surgery.html is a recent thread about converting Canon lenses to Pentax.
05-03-2009, 12:35 PM   #14
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The C mount lenses will not work very well on the Pentax DSLR because of the lens flange to focus plane distance. However the C mount lenses are very adaptable to the Panasonic G1 camera body. So my suggestion is to throw them on eBay and let the G1 user bid on them. I have a couple of C mount adapters and some C mounts lenses for my G1 and I am always looking for more. Please let me know if you want to sell them.
08-25-2009, 02:57 PM   #15
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hi everyone,

i just bought this on ebay: Pentax H6Z810 C60812 8-48 mm F/1.0
Because another seller had c-mount to k-mount, but finally, it is k to c
Bad description.

I bought the lens for 62€ (saw it new for 300€, also on ebay).

Voe mentioned the c-mount to M42 mount (and I could then use a M42 to K mount).

So, should I keep it for macro (if I can find an adapter), cancel the trade or resell it on ebay?
I really don't know what to do here.. I have the feeling I made a mistake by buying that lens..

Thanks for the help.
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