CV 75mm f/1.8 on LTM camera

Phil_F_NM

Phil_F_NM

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Last night I removed the lens flange on my CV 75/1.8 lens to take a look at the mount under the flange and examine what provision I may have for modifying the lens to focus closer than .9m. I'm also thinking about sending the flange to John Milich for 6 bit drilling.

When I took it off I noticed that the main lens mount had a shroud which is coincidentally, the same size as the M39 thread at the depth of the thread cut, not the ridge.

The flange itself rests 1.82mm above the main lens mount which means that there is 1.9mm of space in there to put a simple LTM rear flange on the lens.

This would mean cutting a .3mm thread into the CV lens shroud to allow for the added aftermarket LTM flange to screw on and be held tightly.
It's just an interesting musing I noticed but definitely something to consider since it would be quite easy to turn the threads into the shroud then cut a fully threaded flange for the lens.

LTM users could have quite a nice, fast optic for that Canon or IIIg.
(Along with this idea, I have a bunch of others that I need to get on the ball with.)

Dear Santa, I would like a Baron XL CNC milling machine for Christmas, thank you very much.

Phil Forrest
 
Okay, I googled it.

http://www.cncmasters.com/index.php?page=cnc-baron-xl

Hard to believe how prices have come down for this stuff.

Last CNC I bought was a Milltronics VM-17 at work. $150K. It automatically cleaned up the shards of metal and put them into a container. Surplussed....

On the lens, makes you wonder if there will be a limited edition LTM version.
 
It looks like they built it specifically to have a LTM flange added at the factory so I wouldn't be surprised if we see one.

Thinking about my idea, it would probably be easier to mill down the shroud a few thousandths of an inch and add the LTM flange. Either that, or cut it completely flush with the lens barrel mount then substitute an existing LTM flange from a broken lens and shim it underneath for proper registration.
Way too easy!

Don't expect me to be doing this, though. I don't have any LTM cameras (at the moment) and I have plenty of LTM lenses. But if someone buys me a CNC machine, I'll be happy to convert their lens for them. 😀

Phil Forrest
 
Didn't you have the Komura 80/1.8, Phil ? I use that as LTM "75"/1.8 - works very well.

Would be very interested in a comparison, BTW.
 
I've owned the Komura 80/1.8 but in M42, not LTM. If I had the Komura, I probably would not have bought the 75. Anyways, the 75 is a great lens. I've gone back and forth on selling it twice now. I feel like I'll just buy it back again though since it's a perfect 100mm on the M8.

My next closest lens to the CV75 is a thin 90 T-E. The CV75 beats the pants off the Leica lens, aperture for aperture. I think the CV may be a tad better at f/2 than the T-E is at f/2.8 as well.
That's the closes I've gotten to a comparison with a similar focal length.

Phil Forrest
 
This is a bit off topic but it might be the place to ask; could a IIIc be fitted with a M lens flange. I suspect it would take a lot of machining but a LTM camera with a Leica M lens mount would be the best of both worlds. Pardon me. I get crazy ideas sometimes. Joe
 
It's possible with enough money.
The lens flange to film plane is 1mm shorter in the M bodies than the Barnacks. Add to that the M mount itself is almost a full centimeter wider than M39 plus the locking lugs. Set a Leica M lens flange up against a Barnack & you'll see how little space there is to work with.
It would take some serious work to get that done, but I think it could be done though.
An easier way would be to buy an M3...
**ducks**

Phil Forrest
 
It would be cheaper to buy an M3, M2, or Leica CL unless you can do your own machining. You could probably convert a Nikon S series camera to M-Mount as the RF cam rides the back of the built in helical and you have room to play with. Same with a Contax.

after all, if someone can convert a Contax II to Leica Thread Mount, they certainly could convert it to M-Mount. (Wasn't me!)

http://www.ziforums.com/showthread.php?t=288


More on this amazing conversion.

http://rcbooth.zenfolio.com/p944642472/h97e5377#h97e5377

Converting a Nkon would be easier, the RF follower is easier to adapt.
 
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