Screw to Bayonet adaptors and frames

[lucerne]

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I plan to use a Leica Screw Mount to Leica M Bayonet adaptor on my M9. I notice that there are 2 or 3 Leica variants of the adaptor and each is marked and designed to match one or two lens focal lengths. This is to bring the correct frame lines into the viewfinder. That's as far as I understand. Can someone explain "if", or "how" the dimensions of these adaptors vary in order to achieve this task.

Thanks

Newbie

Lucerne

[bill]

Hello, good afternoon, and welcome

 

In very simple terms, the shape of the adaptor varies. There are three variants, 28-90, 50-75 and 35-135 which correspond to the frameline pairs visible in the viewfinder. Taking an LTM (Leica Thread Mount) lens of , say, 50mm focal length and pairing it with the "incorrect" mount for, say, 35-135mm would bring up the incorrect framelines for the lens.

 

The bit you are looking for is the cut-out that looks like a teardrop shape.. It is that which, through mechanical linkage tells the body what lens (adaptor) is mounted. It is possible to machine a mount to bring up different framelines; for example there are those heathens who have modified the mount of the 40mm Summicron to bring up the 35mm framelines (it would normally bring up 50mm on a Leica M). This is done by shaving away some of the metal. It is clearly harder to add metal, but it can be (and I understand has been) done.

 

Hope this helps!

 

Regards,

 

Bill

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[joeswe]

Hi,

the thickness of the adapters is identical, the difference is in the length of a tab on the side of the adapter that actuates the frame line selection lever inside the camera body.

[alandash]

Which adaptor is correct for the M9-P? I have a screw mount 28mm f2.8 Canon lens, that I used on my 3G. It was very good. It also has the Canon 28mm viewfinder that fit into the flash shoe on top of the 3G.

Is there a built-in 28mm frame line in the M9 that can be activated?

Thanks, Alan Dash

[bill]

The linkages for M cameras after the M2 are identical (the M3 is an isolated case). A 50 year old 28/90mm adaptor will mount your lens to your M9 and bring up the correct framelines as well as one made today. Good quality adaptors are also available from Cosina Voigtlander. Piss-poor ones can be found cheaply on eBay. Buy cheap, buy twice...

 

Regards,

 

Bill

 

Sent from another Galaxy

Edited March 21, 2013 by bill

[UliWer]

The linkages for M cameras after the M2 are identical (the M3 is an isolated case). ...

 

The original Leitz adapters are usually marked for the M3 and M2. For instance:

You find adapters with markings "M2 50" and "M3 28-50". This one won't show the 28mm-frames with an M9, but just the frames for 50/75mm. The markings for the M2 are the right ones.

 

The two versions of Leitz adapters I know, which show the right pair of frames for 28/90mm, are marked "M2 90 M3".

[Michael Geschlecht]

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Hello both Lucerne & Alan,

 

Welcome to the Forum.

 

Alan,

 

When you are looking for adapters there is an earlier version of the adapter which is marked 21 - 50. This is to indicate that it was for using all screw mount lenses 50mm & shorter on the M3.

 

It brings up the 50mm frame lines in any M range/viewfinder & the 75mm frame lines also in M models where that frame is present.

 

It does NOT bring up any frame shorter than 50mm.

 

It was desined for use on an M3 when the only way to see the field of view of a 28mm lens was with an external viewfinder similar to the one used today for a 21mm lens.

 

Best Regards,

 

Michael

[alandash]

What is the best way to safely separate a screwmount lens from the M adaptor, once they are combined too tightly?

1. Connect the combined unit to the M camera, then try to unscrew the lens. That uses the camera as a "vise". Then unlock the adaptor and remove it from the camera. Would that method put too much strain on the camera mount opening?

2. Try to separate the lens from the adaptor off the camera. But how do you get leverage to resist against the unscrewing torque? My hands alone are not enough. Perhaps holding the adaptor edges in a vise, using soft cloths or towels?

I don't want to damage anything while trying.

Alan Dash

[250swb]

Put it on the camera and unscrew. If you try to unscrew it off the camera you are liable to damage the mount or lens because the adapter will distort if you grab it with a pair of mole grips.

 

Steve

[microview]

What is the best way to safely separate a screwmount lens from the M adaptor, once they are combined too tightly?

1. Connect the combined unit to the M camera, then try to unscrew the lens. That uses the camera as a "vise". Then unlock the adaptor and remove it from the camera. Would that method put too much strain on the camera mount opening?

2. Try to separate the lens from the adaptor off the camera. But how do you get leverage to resist against the unscrewing torque? My hands alone are not enough. Perhaps holding the adaptor edges in a vise, using soft cloths or towels?

I don't want to damage anything while trying.

Alan Dash

Yes you slacken it just a little with the lens mounted. Too much and the lens will come out and leave the adapter behind. However, with Voigtlander adapters the cap has three pips which interface with the mounted adapter and this usually resolves the problem.

[philipus]

I've on occasion by accident left the adapter in the mount and, yes, it can be a bit tricky to remove the adapter. However, it can quite easily be done by pushing with the thumb on the inside of the adaptor in a circular motion while pressing the lens release button. However, I have never noticed that this has caused extra stress on the mounts on my M4 and TTL. How tight the adapter "sticks" in the mount depends on the camera. My M4 is much looser than the TTL for instance.

 

I have no problem twisting the adapter off the lens with my hands but it does hurt a bit because of the sharp edges of the adapter. Gloves, towel or something like that is good.

 

The best alternative, imho however, is to attach a rear lens cap to the adapter+lens. Since they're made of plastic, the adapter will come off quite easily once the lens has been unscrewed.

 

Cheers

Philip

[dpitt]

I had some issues lately when I tried to use a 28-90 Leica adapter with my Elmar 50/f3.5.When I mounted it on the M8 it got stuck and I could not focus the lens. It was very hard to click the lens into position and get it off again...

 

 

It works fine with the proper 50-75 adapter. It is only when I misplaced the 50 adapter, and tried the 28-90 I found out there is more to it than only framelines...

[250swb]

The best alternative, imho however, is to attach a rear lens cap to the adapter+lens. Since they're made of plastic, the adapter will come off quite easily once the lens has been unscrewed.

 

 

Ah, rear lens caps, I forgot to mention!

 

What you really need if you use adapters a lot and want to swap the lens between LTM and M quickly is at least one CV M type rear lens cap. They have prongs on the back which locate into the indentations around the circumference of the adapter. So you simply unscrew the lens off the M camera (the safest way) leaving the adapter in place on the M mount, then place the CV lens cap against the adapter and turn it off. It is really just a spanner. Simple!

 

Steve

[earleygallery]

I had some issues lately when I tried to use a 28-90 Leica adapter with my Elmar 50/f3.5.When I mounted it on the M8 it got stuck and I could not focus the lens. It was very hard to click the lens into position and get it off again...

 

 

It works fine with the proper 50-75 adapter. It is only when I misplaced the 50 adapter, and tried the 28-90 I found out there is more to it than only framelines...

 

The adaptors are as simple as they get, bayonet lugs and a screw thread.

 

Using the 28/90 adaptor will bring up those frame lines, but you can screw any lens you choose into it.

 

However, some adaptors don't have the necessary cut out however for the earlier Leica lenses like the Elmar with the infinity lock. If you look you will see some have a flange the same size all round, and others have one which is thinner on one side (to allow for the depth of the infinity lock).

[dpitt]

Thanks for explaining James.

Yes it was the infinity lock.

 

Conclusion is that with lenses with infinity lock, there is more to it than frame only...

[pico]

Some manufacturers have spanner wrench holes in the face of the adapter, and they supply the spanner to make it easier to turn the adapter off the body or lens. Here is one example. I have not used the brand so I cannot recommend, or not.

 

I use Voigtlander adapters and drill the holes myself.

Edited March 24, 2013 by pico

[alandash]

Put it on the camera and unscrew. If you try to unscrew it off the camera you are liable to damage the mount or lens because the adapter will distort if you grab it with a pair of mole grips.

 

Steve

 

I tried to unscrew the lens when it was mounted on my M4, but it was too tight, and I didn't want to break it while trying. Then I just dismounted the whole assembly using the ordinary method of bayonet unlocking, which was easy.

 

I then tried to unscrew the lens from the adaptor, using a cloth around the edges of the adaptor, but that also resisted my efforts. Another viewer suggested mounting a rear lens cap on the lens, but that would not work, since the adaptor is blocking it, and also the counterclockwise turning would just cause the cap to loosen and fall off.

 

Also, some viewers thought I was having trouble removing the adaptor from the camera mount, and gave directions for that, but I did not have that problem at all. I simply want to use my Canon screw lens on my 3G and also my M cameras, and want to easily switch back and forth, with and without the adaptor. Would it be safe to use a tiny drop of oil where the threads of the lens and adaptor meet?

 

Thanks to all for your help.

[bill]

... Another viewer suggested mounting a rear lens cap on the lens, but that would not work, since the adaptor is blocking it, and also the counterclockwise turning would just cause the cap to loosen and fall off.

...

 

That does work... Really. In what way is the adaptor blocking it? We do mean an M end cap on the adaptor not an LTM end cap on the lens.

 

DON'T use oil - your last state will be worse than your first!

 

Regards,

 

Bill

 

 

Sent from another Galaxy

[arnipall]

try to take the lens with the adapter and warm it up a bit then cool it fast down

then the smaller thing shrinks down and should become loose.

this will not put strain on anything.

ap

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[spydrxx]

On occasion when I've tightened a sm lens too tightly in the adapter, and I don't want to strain the parts on the M body holding the adapter/lens combo, I merely remove the entire unit from the camera body. I then grab a perforated rubber mat jar opener grip from a kitchen drawer (they also sell in larger rectangular shape sheets as drawer liners - about $1 USD each in discount stores...about 3x as much in regular grocery stores), and the adapter esily unscrews from the rear of the lens. I've taken to placing one of the grips into my camera bag just in case.