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Removing CV25 bayonet mount - advice required

jlancasterd

By jlancasterd
in Leica M8 / Leica M8.2

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jlancasterd

jlancasterd

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I have discovered, by trial and error, that pure acetone (available from my local chemist at £1.21 for 50ml) will soften the locking adhesive that CV uses on the screws which hold the bayonet mount onto my CV40mm Nokton. However, this appears to loosen much more than the mount itself - the depth-of-field ring certainly became very wobbly. I therefore chickened out of removing the mount entirely as I don't really need to get it coded (I generally use it only with my Bessa R3A).

 

I am, however, considering the purchase of one of the new M-mount CV 25mm lenses for use with my M8 and will very likely want to get it Milich-coded. I assume that I will be able to loosen the screws holding the bayonet mount in place with acetone as I did with the 40mm. Can anyone tell me if it is then possible to remove the bayonet without disturbing the rest of the lens?

 

Or maybe I should just stick to CornerFix...

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wparsonsgisnet

wparsonsgisnet

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John, I have the CV25 with the Milich sandwich (hood and ltm-to-bayonet adapter). The adapter just screws on to the CV25 which is a screw-mount lens.

 

To tighten the adapter, I twisted the lens (carefully) while the adapter was snapped in on the M8. To remove (and I did this to remove the CV adapter that came with the camera) I carefully twisted the other way. Of course, this leaves the adapter on the camera. There is a notch on the adapter and I used a plastic thingy to push it gently while depressing the lock button.

 

Milich's stuff is worth every penny.

 

I am not that excited about the lens, tho. Just spoiled by Leica glass, and waiting for their wide lens.

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jlancasterd

jlancasterd

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John, I have the CV25 with the Milich sandwich (hood and ltm-to-bayonet adapter). The adapter just screws on to the CV25 which is a screw-mount lens.

 

To tighten the adapter, I twisted the lens (carefully) while the adapter was snapped in on the M8. To remove (and I did this to remove the CV adapter that came with the camera) I carefully twisted the other way. Of course, this leaves the adapter on the camera. There is a notch on the adapter and I used a plastic thingy to push it gently while depressing the lock button.

 

Milich's stuff is worth every penny.

 

I am not that excited about the lens, tho. Just spoiled by Leica glass, and waiting for their wide lens.

 

Thanks Bill

 

I know about the Milich adapters for the old, discontinued screw-thread CV25 - I have several fitted to other CV lenses.

 

However, the new rangefinder-coupled CV25, only recently introduced, comes with a Leica M-mount held on by 4 screws. It is these I want to remove so that I can send the mount to John Milich for the 6-bit coding slots to be milled. However, I'm not sure if this is possible without disturbing the rest of the lens.

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sean_reid

sean_reid

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Thanks Bill

 

I know about the Milich adapters for the old, discontinued screw-thread CV25 - I have several fitted to other CV lenses.

 

However, the new rangefinder-coupled CV25, only recently introduced, comes with a Leica M-mount held on by 4 screws. It is these I want to remove so that I can send the mount to John Milich for the 6-bit coding slots to be milled. However, I'm not sure if this is possible without disturbing the rest of the lens.

 

It's a great question. I'm reviewing the 25P and 21P right now and the RF-coupling on the new 25 is a huge advantage. I'll be curious to hear what you find out.

 

Cheers,

 

Sean

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jlancasterd

jlancasterd

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I was able to remove the mount with a small screwdriver and no chemicals. One of them was a little stiff but still came off with no damage. I haven't received it back from JM yet so I can't speak as to how it works out.

 

DD

 

Thanks David - that's what I'd hoped to hear.

 

When you get the mount back and have refitted it, could you post again with your impressions of its performance when coded?

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sean_reid

sean_reid

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Sure, If you don't see anything in a few weeks just drop me a line. I found that I really liked the lens on film but did not care for it on my RD-1. I haven't tried it on the M8 yet.

 

DD

 

Like most of the Skopars, the CV 25 vignettes a lot on the R-D1.

 

Cheers,

 

Sean

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wparsonsgisnet

wparsonsgisnet

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Hi Bill,

 

You mentioned that about the 15 too. What is it that you don't like about each one?

 

Cheers,

 

Sean

 

Sean, I have the 15 with John Milich's adapter and hood. It's like other lenses I have tried that are not Leica glass. The "roundness" of the image is missing from other guys lenses.

 

I've never used Zeiss lenses, but all the others I've tried disappoint. The Leica lens presents the image in a 3-dimensional, palpable way that I have come to depend upon. I like the depth of image that is in what should only be 2-dimensional.

 

The pix from the CV15 are ok, just missing the magic I expect to see.

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etrigan63

etrigan63

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It's a great question. I'm reviewing the 25P and 21P right now and the RF-coupling on the new 25 is a huge advantage. I'll be curious to hear what you find out.

 

Cheers,

 

Sean

 

I will eagerly await this review. I am keenly interested in the 25P as my next lens.

 

I was able to remove the mount with a small screwdriver and no chemicals. One of them was a little stiff but still came off with no damage. I haven't received it back from JM yet so I can't speak as to how it works out.

 

DD

 

I had the same experience with my CV 40mm Nokton. A high quality jeweler's screwdriver is all that is needed to remove the flange. No chemicals needed. The trick is make an alignment mark on the flange with a permanent marker to ease reassembly. I usually put a mark on the flange that lines up with the red mounting dot.

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sean_reid

sean_reid

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Sean, I have the 15 with John Milich's adapter and hood. It's like other lenses I have tried that are not Leica glass. The "roundness" of the image is missing from other guys lenses.

 

I've never used Zeiss lenses, but all the others I've tried disappoint. The Leica lens presents the image in a 3-dimensional, palpable way that I have come to depend upon. I like the depth of image that is in what should only be 2-dimensional.

 

The pix from the CV15 are ok, just missing the magic I expect to see.

 

Hi Bill,

 

In the end, that comes down largely to contrast. The contrast separation in the mid-tones is a large part of what creates the "three-dimensionality" you're talking about. The Zeiss lenses actually tend to have even more contrast than the Leica lenses.

 

Do you want a suggestion for ways to boost that micro-contrast?

 

BTW Bill, did you used to do your own darkroom work when you were shooting film? If yes, did you tend prefer negatives with higher or lower contrast? I've been thinking about this and suspect that photographers who are used to seeing pictures, straight from the camera, that are more or less in their final forms, may find something lacking in files made with more moderate contrast lenses. Photographers who start with those lower contrast files as a base and then build the final print from there tend to like having the additional tonal scale of lower contrast lenses.

 

So, much of this may come down to how one works and what or her references points are with respect to film photography.

 

Cheers,

 

Sean

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jaapv

jaapv

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I have discovered, by trial and error, that pure acetone (available from my local chemist at £1.21 for 50ml) will soften the locking adhesive that CV uses on the screws which hold the bayonet mount onto my CV40mm Nokton. However, this appears to loosen much more than the mount itself - the depth-of-field ring certainly became very wobbly. I therefore chickened out of removing the mount entirely as I don't really need to get it coded (I generally use it only with my Bessa R3A).

 

I am, however, considering the purchase of one of the new M-mount CV 25mm lenses for use with my M8 and will very likely want to get it Milich-coded. I assume that I will be able to loosen the screws holding the bayonet mount in place with acetone as I did with the 40mm. Can anyone tell me if it is then possible to remove the bayonet without disturbing the rest of the lens?

 

Or maybe I should just stick to CornerFix...

 

You only need a mini-drop, it is not a good idea to soak it.

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jlancasterd

jlancasterd

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You only need a mini-drop, it is not a good idea to soak it.

 

Yes - I agree. I applied it using a very small, stiff, artist's paint brush. The main problem is that acetone is very volatile, so keeping the brush moist isn't always easy.

 

Incidentally, acetone is also very flammable so don't smoke whilst you are using it... :rolleyes::eek:

 

The problem I encountered with the CV40 is that removing the screws in the M-mount appears to loosen the depth of field ring (and possibly other components) as well as the mount itself. As I was only experimenting and didn't actually want to remove the mount, I went no further.

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