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Arri to CP adapter


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#1 Mike Rizos

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Posted 31 May 2006 - 08:58 PM

I bought what was described as an Arri bayonet to CP adapter on ebay, and don't understand how the Arri lens would stay on. I don't have any Arri lenses at the moment, but on the Arriflex cameras that I've seen there is two lens release/lock levers on the camera body, which this adapter doesn't have, so what keeps the lens from turning, or falling off? Is this possibly a home made adapter, although it seems to be of very high quality. Also from my understading a bayonet mount will accept standard mount lenses. Am I right to assume this?
Mike
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#2 Tim Carroll

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Posted 31 May 2006 - 09:35 PM

I bought what was described as an Arri bayonet to CP adapter on ebay, and don't understand how the Arri lens would stay on. I don't have any Arri lenses at the moment, but on the Arriflex cameras that I've seen there is two lens release/lock levers on the camera body, which this adapter doesn't have, so what keeps the lens from turning, or falling off? Is this possibly a home made adapter, although it seems to be of very high quality. Also from my understading a bayonet mount will accept standard mount lenses. Am I right to assume this?
Mike


See if you can post a few pictures of the adapter and maybe we can help you find a way to use it. It is hard to tell what it is from your description. The ARRI bayonet mount will accept ARRI standard mount lenses, you are correct.

-Tim
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#3 Josh Hill

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Posted 01 June 2006 - 03:17 AM

I'm pretty sure I Know what adapter you got. Keep in mind that there are two Arri mounts: PL Mount (which has release lock levers) and the Arri B mount (which does not). (I wasn't sure if the Standard mount is an Arri mount or really what the name applies so I didn't include that.) I am 99% positive you bought a B mount adapter since they are the only adapters I have seen on eBay.
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#4 Ian Marks

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Posted 01 June 2006 - 11:23 AM

I'm pretty sure I Know what adapter you got. Keep in mind that there are two Arri mounts: PL Mount (which has release lock levers) and the Arri B mount (which does not). (I wasn't sure if the Standard mount is an Arri mount or really what the name applies so I didn't include that.) I am 99% positive you bought a B mount adapter since they are the only adapters I have seen on eBay.


I have differ with Josh here. There are three Arri mounts, the PL, the bayonet and the standard. You have either the bayonet or the standard (Visual products can modify the CP16R body to a PL mount, but there is no economic incentive for anyone to manufacture a CP to PL adapter, as the cost of the adapter would probably be close to the value of a used CPR body).

Anyway, I have both the bayonet and standard adapters for my CP. There are going to be variations, of course, depending upon who manufactured the adapter, but generally, the standard adapters attach to the lens with there tiny set screws which are tightened with a hex wrench to the lens. The ones I have are painted black, and I think they're made out of bronze. The bayonet models are usually in stainless steel, and will have a channel in the opening for the lens, and a means of twisting the lens into place once it's fully seated. It may or not have some kind of locking ring, again depending on the manufacturer. I don't have my adapter in front of me right now, so I'm just writing this from memory, but I think if you insert a bayonet mount lens into your bayonet mount adapter, it should all become self evident.

Yes, you can put a standard lens in a bayonet adapter, but not vice-versa. Also, this will probably be a less-than-ideal "friction fit" arrangement. I would stick to putting lenses into the mounts for which they were designed (bayo->bayo, and std->std).
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#5 Mike Rizos

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Posted 01 June 2006 - 08:57 PM

Thanks for the replies, nice to hear from you guys again. I've attached a pix. It must be a bayonet adapter, and like Mark says it has threaded holes on the sides, but no screws. Do bayonet lenses need screws also? That will be a pain to do eveytime I change lenses.
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#6 Hal Smith

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Posted 01 June 2006 - 09:34 PM

Yes, you can put a standard lens in a bayonet adapter, but not vice-versa. Also, this will probably be a less-than-ideal "friction fit" arrangement.

Not if you've got Cooke Speed Panchro lenses in Arri Standard mount. A "true" standard mount has a tab that slides into a slot in the lens to locate (index) it. The Cooke focus mechanism uses that tab to hold the inner part of the lens in one position while the entire outer barrel rotates for focus adjustment. I had a Zeiss Opton for a short while for my Arri 2 - it used the tab only to keep the lens from rotating in the mount, the set screws found in some Bayonet > PL adapters would probably work to keep a Zeiss from rotating.
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#7 Ian Marks

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Posted 02 June 2006 - 12:42 PM

Thanks for the replies, nice to hear from you guys again. I've attached a pix. It must be a bayonet adapter, and like Mark says it has threaded holes on the sides, but no screws. Do bayonet lenses need screws also? That will be a pain to do eveytime I change lenses.


I have the same adapter. I think you'd use some little set screws in those holes to secure a standard mount lens in your bayonet adapter. I'm not sure where you'd get them - a lens tech would be a good bet. Like you, I don't have an Arri-bayonet lens to put in my adapter. I do have two standard Arri-mount lenses mounted in standard mount adapters, and each of those uses the tiny set screws.

It's important to note that the adapters get mounted to the lenses and stay there. Some adapters, like the CP to Nikon, can be mounted to the camera and stay on it, effectively converting it to a Nikon-mount camera (or can stay on the lens - your choice). Hope this helps.
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#8 Robert Skates

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Posted 03 June 2006 - 08:50 PM

For those interested, here are a few lenses that do not work with the Arri standard to CPR mount adapter:

-Schneider Cine-Xenon 1:2 16mm
There are two models of the 16mm I tried the one with the deep set, small front element, no go. The rear housing bumps the ground glass when the focus is set further than 1.4' or so.

-Carl Zeiss Jena Biotar 1:2 35mm
Like most of the cookes it utilizes and external focus barrel rotation.

As I try more I'll post the results.

Robert Skates
http://sk8scamera.com
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#9 Ian Marks

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Posted 05 June 2006 - 02:02 PM

For those interested, here are a few lenses that do not work with the Arri standard to CPR mount adapter:
http://sk8scamera.com


Right... there are going to be some lenses with clearance issues, just as there are some lenses that work on the Arri 16S/16M/16BL but would not work on the SR. My Cooke 12.5mm has been modified to clear the mirror on the SR and clears the mirror on the CPR as well. The modification involves trimming a little bit of the metal near the rear element.
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#10 Dave Wowchuk

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Posted 05 August 2006 - 02:17 PM

Hi everyone,

So, if I understand correctly ... lenses with the 41mm ARRI mount CAN be used with the 54mm PL/Bayonet adapter, but you will have to use the set screws to hold the lens firmly in place? (Otherwise my M-One focus motor will spin the lens loose.)

Dave
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