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C-Mount lens adapters

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Catama Productions
C-Mount lens adapters
on Mar 28, 2011 at 4:22:47 pm

Hey All,

I have a t2i and a 7d. We were cleaning out our basement, and saw our old Bolex kit, and it occured to me that we had a couple nice lenses for that kit.

So I bought a 25 dollar adapter to use C-Mount Lenses on Canon EOS. I figured for 25 bucks it was worth a try.

The lenses mount fine, but the focal plane seems really messed up. Basically, every lens work like an intense Macro lens. I hooked up a Paillard 70mm to my T2i and the only thing I could focus on was literally 8 inches away from the lens.

I understand only the basics of lens structure, but it seems there would be a way for me to use these lenses. Maybe by moving the lenses closer to the chip?

Has anyone messed around with this yet, and have you had any luck?

or, alternatively,

can anyone give me a basic explanation of why this is not working?



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Jonathan Ziegler
Re: C-Mount lens adapters
on Mar 28, 2011 at 5:51:35 pm

Part of the problem is that a 16mm film frame is considerably smaller than the APS-C sensor. In order to get a good focal length, you have to put the lens farther away which also increases the focal length (making everything magnified). What is the converter you used? Can you send a link?

Jonathan Ziegler
http://www.electrictiger.com/
520-360-8293


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Catama Productions
Re: C-Mount lens adapters
on Mar 28, 2011 at 6:01:29 pm

sorry. here is the link.

http://www.fotodiox.com/product_info.php?products_id=487

So if i added some distance, like with an extension barrel, that would increase the Depth of field? Magnification is not a problem, as most of the lenses are below 100mm. And I am just using them because i have a project where I thought it might be cool to have a little vignetting/edge deformation.



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Jonathan Ziegler
Re: C-Mount lens adapters
on Mar 28, 2011 at 10:12:40 pm

Well, according to the link you sent, it says: "Infinity Focus: No; Limited Focus Range, Macro Only." This means you'll only be able to use close-focusing with limited depth of field. You would need optics in an adapter to make a C-Mount lens work with a DSLR camera.

Jonathan Ziegler
http://www.electrictiger.com/
520-360-8293


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Phil Balsdon
Re: C-Mount lens adapters
on Mar 30, 2011 at 1:35:52 am

Adding distance between the lens and mount will increase the problem.
As has already been mentioned your sensor size is much bigger than the 16mm format these lenses were intended for.
Your second and major problem is the focal plane of the camera is too far back from the lens. You could only rectify this by removing the mirror from the camera (as they do with PL mount conversions) and building a mount that allows the lens to intrude into the camera body.
You really don't want to go there, especially as it may not work and the process may not reversible and leaves your camera useless for stills work.

Cinematographer, Steadicam Operator, Final Cut Pro Post Production.
http://philming.com.au
http://www.steadi-onfilms.com.au/


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Jonathan Ziegler
Re: C-Mount lens adapters
on Mar 30, 2011 at 9:10:53 pm

Phil, thanks for chiming in, that was the part I wasn't totally sure about.

There are hundreds of unused c-mount lenses out there. If you can get a really small focal length, you can probably get some really interesting results. Maybe a 16mm sized tilt-shift?

Also, the T2i will let you do a 640x480 crop sensor (don't remember on the 7D) which could give you some more interesting results. Use a tripod. ;)

Jonathan Ziegler
http://www.electrictiger.com/
520-360-8293


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Catama Productions
Re: C-Mount lens adapters
on Mar 31, 2011 at 2:20:58 pm

This is all so useful to me, you guys. Thanks so much.

@Phil: I am certainly not interested in moving any parts of the camera just so i can use a 30 year old 16mm lens! So don't worry about that. I was wondering how the optics worked, and you cleared that up. Thank you very much. I just wanted to clarify though, that you are pretty sure there is no way to use any of these 16mm lenses. I would think some sort of optics may work, but am I mistaken? I found this

http://www.viewsolutionsinc.com/products/Digital%20Camera%20Adapter.htm

I have no idea if this would work.

I guess I am just trying to find some old lenses for cheap that I could use for a video I am producing that has some "Historic" moments in it. A lens that would give me DOF, but maybe still have some vignetting and/or a softness. The canon lenses are just too sharp!

Any ideas?

@Jonathan: As cropping the image to 640x480 is not physically changing the size of the chip, would that actually work. I am going to try it today, just to see, but my camera is not here right now.

Thanks guys! This is quite interesting for me. I appreciate the learnin'.



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Fred Dorsett
Re: C-Mount lens adapters
on Apr 8, 2011 at 12:00:03 pm

Hi,
If you have some 'historical' shots you need to add to your project,
the best, and most 'visually' effective method, might be to shoot tham on the Bolex H16 using your 16mm lenses (onto B&W stock at 16fps), and then have the processed footage 'digitised' to cut into your timeline. The results would certainly have the 'right' patina for 'historic cutaways !
Just a thought !
Best regards
Fred. (DSLR Video and 16mm Arriflex shooter)


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Adam Finelli
Re: C-Mount lens adapters
on May 19, 2015 at 11:25:19 pm
Last Edited By Adam Finelli on May 19, 2015 at 11:30:32 pm

I got blurry images with a Kodak 16mm lens fixed to a Canon EOS 7D using a C-Mount to Canon EOS adapter. I stumbled on this thread. Catama Productions' comments here inspired me to take the camera set-up out for one more spin as an "intense Macro lens." You can see a video from the footage I produced at this URL: https://vimeo.com/128317671.

Thanks for the suggestion,

Adam
http://www.adamcamera.com


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