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Lesn mount oddities


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#1 David Auner aac

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Posted 15 September 2007 - 03:08 AM

Hi folks,

as some of you might know my NPR has a C mount and an Arri B mount. From what I read on the web, the B mount should take Arri St as well. So far so good.

I picked a an Angenieux 17.5-70 T2.2 on ebay in Arri St, worked like a charm. So far so good.

Yesterday I went to a used camera store and tested a number of lenses on the camera. They had a rather beautiful 10-100 2.8 Vario Sonnar which said for Arri SR only, it had strange coupling sticks on the back side, which I assume are for the Auto Iris or something like that. Wouldn't fit, no surprise.

We then tried to fit a really old Schneider Cinegon that was probably made for the Arriflex 16. It fit, but the focus wouldn't turn properly when you grabbed the ears, but you could focus when turning the front element, but not very well.

I then tried 3 different 85 f2 Sonnars, two from Jena, one from Oberkochen. The oldest one, a Jena without T coating worked about as well as the Schneider mentioned above.
The next one, again from Jena, this time with T coating, worked the same again. And the newest one, the Oberkochen one with T, worked like a charm.

So my question is: are there two generations of Arri St mounts? The older ones seemed to be aluminum, the newer ones stainless steel. So my guess is that the Arri St mount lenses with the alu barrels have a different focus mechanism than the Arri St mounts with stainless steel barrels. Does anyone have any idea here?

The guy in the shop and I were really surprised and could hardly believe our eyes!

Thanks & best regards, Dave
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#2 David Auner aac

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Posted 15 September 2007 - 03:43 AM

Sorry for the typos, I was just having my morning cup of Espresso.... :D

Cheers, Dave
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#3 Leo Anthony Vale

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Posted 15 September 2007 - 12:53 PM

On the older lenses the entire mount rotates when focusing. The blade in the std. mount on the camera slips into a slot on the lens, keeping the body of the lens from rotating while the mount is rotating.
This makes using adaptors a problem.

On later models the mount doesn't rotate.
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#4 David Auner aac

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Posted 16 September 2007 - 03:40 AM

On the older lenses the entire mount rotates when focusing. The blade in the std. mount on the camera slips into a slot on the lens, keeping the body of the lens from rotating while the mount is rotating.
This makes using adaptors a problem.

On later models the mount doesn't rotate.


Thanks Leo, that confirms what I figured. Any idea on how to fix this? Could I maybe modify my Arri B mount somehow? Or just be sure to use newer lenses? Which would be a pity as I think it's charming to use those lovely pieces of old glass...

Thanks, Dave
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#5 Leo Anthony Vale

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Posted 18 September 2007 - 01:58 PM

Thanks Leo, that confirms what I figured. Any idea on how to fix this? Could I maybe modify my Arri B mount somehow? Or just be sure to use newer lenses? Which would be a pity as I think it's charming to use those lovely pieces of old glass...


I don't know if the B-mount can be modified.
There are some PL adapters around that will work with the older mounts. The Cooke S.P. Series II & III have the rotating mount, these adaptors were made with those in mind.
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#6 David Auner aac

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Posted 18 September 2007 - 03:25 PM

I don't know if the B-mount can be modified.
There are some PL adapters around that will work with the older mounts. The Cooke S.P. Series II & III have the rotating mount, these adaptors were made with those in mind.


Thanks Leo. It seems that Les will mod my NPR to PL anyways. He is selling an adapter to Arri Std he mentioned with Cooke lenses. So I guess that will work.

Cheers, Dave
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#7 Brian Drysdale

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Posted 18 September 2007 - 03:55 PM

I had a Zeiss 10-100 T3 zoom with an Arri B mount that I used on a CP16 and an Aaton. I believe they just removed the iris pins.
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#8 John Sprung

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Posted 18 September 2007 - 04:04 PM

Thanks Leo, that confirms what I figured. Any idea on how to fix this? Could I maybe modify my Arri B mount somehow? Or just be sure to use newer lenses? Which would be a pity as I think it's charming to use those lovely pieces of old glass...

Thanks, Dave

The difference is that the lenses with self-contained focusing contain some lubricant, while the ones that rotate within the mount are dry on the outside. The modification to try is just a small amount of some clean lubricant, like Tri-flon or whatever it's called. I've got the can at home. The Eyemo mount has the same problem.



-- J.S.
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#9 David Auner aac

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Posted 18 September 2007 - 04:23 PM

I had a Zeiss 10-100 T3 zoom with an Arri B mount that I used on a CP16 and an Aaton. I believe they just removed the iris pins.


Yep, there is a version with and a version without these pins. But the 10-100 isn't a good idea since the camera will be S16 soon.

Cheers, Dave
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#10 David Auner aac

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Posted 18 September 2007 - 04:26 PM

The difference is that the lenses with self-contained focusing contain some lubricant, while the ones that rotate within the mount are dry on the outside. The modification to try is just a small amount of some clean lubricant, like Tri-flon or whatever it's called. I've got the can at home. The Eyemo mount has the same problem.


Thanks John. Will try that when I find a cheap one to buy and lube up.

Cheers, Dave
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#11 John Sprung

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Posted 18 September 2007 - 04:51 PM

Thanks John. Will try that when I find a cheap one to buy and lube up.

Cheers, Dave

Be sure to use just a tiny amount of lubricant, just barely enough. Start by cleaning the outside of the lens and inside of the mount with rubbing alcohol, again using as little as possible. If you find galling or burrs on either, carefully remove them with crocus cloth or a fine grit emery paper, like 400 - 600 grit, and clean everything again. If the seller of the lenses knows their stuff, they'll let you try that before you buy.



-- J.S.
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#12 David Auner aac

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Posted 18 September 2007 - 05:18 PM

Thanks, John. Could you check the name of the lubricant and what kind it is? I might not be able to get the same brand here in ol' Europe...

Regards, Dave
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#13 Charlie Peich

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Posted 18 September 2007 - 06:43 PM

Thanks, John. Could you check the name of the lubricant and what kind it is? I might not be able to get the same brand here in ol' Europe...

Regards, Dave


Dave,
You need to get from Arri - Arri Special Grease (Spezialfett) Isoflex LDS 18/05 -- comes from Arri in a yellow tube. Arri part # K5.50574.0
Charlie
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#14 John Sprung

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Posted 18 September 2007 - 08:24 PM

Dave,
You need to get from Arri - Arri Special Grease (Spezialfett) Isoflex LDS 18/05 -- comes from Arri in a yellow tube. Arri part # K5.50574.0
Charlie

Arri grease is actually for the movement of the II-C. What you want is something less sticky, so it won't trap dust. What I use is a Teflon spray, just spray a little on a clean cloth, and wipe inside the camera and outside the lens. Even so, you'll have to clean and re-lubricate from time to time.



-- J.S.
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#15 Charlie Peich

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Posted 19 September 2007 - 04:46 PM

Arri grease is actually for the movement of the II-C. What you want is something less sticky, so it won't trap dust. What I use is a Teflon spray, just spray a little on a clean cloth, and wipe inside the camera and outside the lens. Even so, you'll have to clean and re-lubricate from time to time.
-- J.S.


Sorry about that, I didn't realize the Arri Special grease was just for the movement. I don't have a 2C, so I'm not familiar with it's movement lubrication. I've loaned out my "Arri lubrication scheme" for all cameras up to 1982. I do remember when Reagan was the "teflon" president however. :lol:
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#16 John Sprung

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Posted 19 September 2007 - 06:59 PM

You could use the Arri grease if you had nothing better. But you'd have to be more careful and clean and re-lube more often, as it tends to spread around and collect dirt.




-- J.S.
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