Archived posting to the Leica Users Group, 2015/11/02

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Subject: [Leica] The SL
From: red735i at (Frank Filippone)
Date: Mon, 02 Nov 2015 23:00:00 -0800
References: <>

An excellent description of the mechanism.... and especially the variants.

Yes, rather difficult to implement....  especially if you wanted to be 100%
compliant with all lenses of any age........

Frank Filippone
Red735i at

The Leicaflex (original) used a sloped cam outwardly similar to an M lens'
focussing cam.  The body's axial cam follower (at the top of the mirror box)
read this cam as actual lens aperture (for the non-TTL meter, much like the
Nikon F rabbit ears).  The Leicaflex SL and SL2 use a second sloped cam,
similar to the first but at the bottom of the mirror box, that indicated
aperture relative to full aperture for TTL metering (like auto-indexed
rabbit ears or Nikon's AI tab).  The R cam (R3 onward) a.k.a. 3rd cam used a
rotational cam that indicated both actual aperture and aperture relative to
maximum.  It would be messy to sort these out in an adapter.

Doug Herr
>One word answer..... No.
>The easy part is the auto aperture.... which is a simple linear 
>actuator requirement.  The hard part will be the transfer of set 
>aperture to the body.
>I have forgotten ( if I even ever knew)  how the Leicaflex transferred 
>Aperture information to the body, but I do not think it was 
>electrical... I think it was a mechanical linkage....
>That could be done with a pretty simple resistive element.....   If this
>were implemented, it would mean Aperture Priority only.....  ( metering 
>system adjusts shutter speed to get proper exposures)
>Again, my Analog Circuit Design background allows me to think of 
>this... it does not mean Leica agrees.....
>Frank Filippone
>Red735i at
>Is there any technical reason why this is difficult (Auto Exposure 
>feature for R lenses)? Nikon DSLR AF lenses work fine on the Nikon 1 
>mirrorless systems, with both AF and AE (most features) enabled via an
>On Tue, Nov 3, 2015 at 5:37 AM, Frank Filippone <red735i at>
>> If it were as easy as a simple tube, which is the adapter without the 
>> auto feature, there is no reason that it would not have been 
>> available now.  It is so trivial, that the Chinese copy cats have 
>> probably already
>done it.....
>> ( somewhat tongue in cheek.)... Checking after I wrote that, I found 
>> that Novoflex has the adapter ( dumb, no auto feature), called the 
>> LET/LER.  So you can use your R lenses on your SL body, as soon as 
>> they
>ship them.....
>> That is the primary reason I think that it will the Auto feaqture..... 
>> that it is taking a year to come out.....
>> I have no real info, nor am I on the inside track at Leica.....  I am 
>> purely speculating...
>> But if it did have the Auto feature, it would be the single most 
>> brilliant implementation Leica has had since the LTM to M adapters.....
>about 1953.
>> Frank Filippone
>> Red735i at
>> Actually I was told by a Leica rep at PhotoExpo that the R adapter 
>> would not have an auto stop down mechanism. Of course he could be 
>> wrong, or they might reconsider....
>> On Mon, Nov 2, 2015 at 6:01 PM, Frank Filippone <red735i at>
>>> There is no published information that the R to TL adapter has or 
>>> has not the auto stop down abilities.
>>> The R to M adapter plus the M to TL adapter, which they now 
>>> recommend until the one piece adapter becomes available, does not.
>>> Frank Filippone
>>> Red735i at
>>> The facht that the R adapter tube does not stop down R lenses seems 
>>> a problem to me, however perfect this camera would be.
>>> Cedric Agie
>>> Brussels

In reply to: Message from wildlightphoto at (Doug Herr) ([Leica] The SL)