compatibility M-body with C-lens

[d._p.1]

hello, <br><br>A reputed Leica repairman here in Holland told me part

of my focussing problems (see the &%^$%^^%$%^GRGRGR!!!-thread below)

are caused by using a Leica 90/4.0 elmar C (with the emphasis on

<B><i>C</i></B>) on my M2. He says the curved part of the lens into

which rangefinder arm extends is steeper than that of M-lenses, hence

the focus error. <br>On the other hand, the guy who sold me the lens

and whom I equally trust, believes the focus error should be on the

rangefinder side - not on the lens side. Two "experts" contradicting

eachother, leaving my problem unsolved. <br>Does anyone here has an

informed opinion or first hand experience on the above?<br><br>many

many thanks!<br><br> dp

[peter_white2]

There is no compatibility issue with any of the Leica C lenses made for the CL when used with any M body, other than the frame line problem with the 40mm lens. The 90mm is 100% compatible.

 

The Leica CL has a 40mm frame lines for the 40mm Summicron. No M body has the 40mm frame lines.

 

But they all focus properly, unless there is a mechanical problem.

 

PJW

[kaiblanke]

I have an Elmar-C working perfectly on a Leica M2. If your lens is a Rokkor (the one for the CLE), then there should be no problem with the camera since the CLE Rokkors have the same cam as the M lenses.

<p>

The CL lenses indeed have another cam, which apparently for some M3's is a problem, but I have yet not heard about another Leica having problems with it. With the M6 and the M2 it should work fine - I tried both with satisfying results. The only problem can be that both lens and camera of the seller have been in common mis-alignment, but then he would encounter problems with another lens.

[dan flanders]

Like the bumblebee, who knowing nothing of aerodynamics, flies anyway; and despite that according to aerodynamics it is impossible for him to do so, I have continued to use my Summicron C, 40/2.0 and Elmar C, 90/4.0 with my M Leicas; and having so done, have not experienced any perceivable focusing problems with the resulting images. Similarly, I used my Elmar 135/4.0 on my CL despite official warnings that it would not focus accurately.

 

I attempted to analyze the geometry involved in order to determine if there was any significant difference in the focusing accuracy between the range finder camming methods, e.g. the flat cam on the standard M lenses and the sloping cams on the Cs. My measurements are only approximate but I believe they are within reasonable tolerances, and my calculations are according to my elementary familiarity with trigonometry.

 

I have only my IIf readily at hand bit assume that its geometry is similar to that of the M cameras. The measured diameter of the rolling cam follower is 8mm, more or less. Assuming that the follower is positioned at the centerline of the lens, the accompanying sketch diagram was constructed in order to calculate the possible difference in travel of the follower due to the sloping face of the cam on the C lenses compared to that of the level face on the M lenses.

I believe that the accompanying sketch diagram and the calculations are self explanatory so I will not attempt to describe them in detail. Suffice it to say that it was determined that there might be a possible difference of 0.0167mm in cam follower displacement between the two systems for the 40mm lens.

 

Though I am not privy to the design tolerances of the lenses I am inclined to the opinion that the difference is within the focusing tolerance expected of those lenses.

 

Recognizing that I might be ignorant of the total factors involved, I would be interested in observations regarding this issue. Jay, in particular, may have some well considered input on the matter.<div></div>

[joel_matherson]

I have the 40 and 90 C lenses and also their CLE conventionally cammed equivalents and cannot note any focusing differences or iregualarities between the two types, tried on various M's and CLE's. I would guess a rangefinder problem in this case provided that the cam in the lens isnt faulty which is always a possibilty on any RF lens but far more likely its camera rangefinder alignment.

[joel_matherson]

Harry, I would be interested to hear more of your use of the 135 and the CL. I have always heard good things about the 135 Tele Elmar but have been reluctant to get one because i mainly use CL's/CLE's. Does it focus well close up wide open? THanks

[dan flanders]

First off, I should admit that presently I do very little work with the 135 directly on the my Leica, rather in the past I have used it more with one or the other Visoflexes. When I lived in Alaska I was particularly interested in waterfoul and other birding photography and used the 135, 200, and a 500mm converted Takumar for such work. Early in the game I sold the CL and acquired a CLE outfit. You are probably aware that though the RF base of the CLE is shorter than that of the M, it is longer that that of the CL or LTM. (Rats, I hate the LTM designation. I don't know the rationale of its adoption but until recently it was logically known as SM as opposed to BM, and think I just might defiantly revert thereto in future imusings.)Thus, having the same cam system as the LTMs it is reasonable to assume that the 135s performance on the CLE should at least match that of the LTMs and since the base length on the CL was approximately that of the LTM, then why should that make a difference? The reason just might be the possibility that the RF geometry of the CL differed in some significant way from the LTM and the M, and Leica, adhering to a policy of strict specification wanted to cover their behinds. To make a long story short, eventually I traded the 135/4.0 for a Snap Shot Skopar, and due to health and physical limitations have not indulged in long lens photography since moving to Texas six years ago. I might be able to scare up a couple of images taken with the 135 and th 500, and will post them if you are interested.

Regards,

HG

[tom_brabant]

If my memory serves me correctly, I have to in some degree give credence(sp) to the advice of the Holland repairman. About l976, I bought and used a CL. Used a 50mm M and 90mm M on it. BUT I read in Leica Photografie, or somewhere, that there could be a slight problem the other way around--with the C lenses used on the M cameras. And it had to do with the angle of the cams. Gee, that's been years ago; I don't remember exactly. I didn't pay much attention, as I was going the other way.

[gary e]

I have the 40/2 summicron-c and 90/4 elmar-c and use them on an M3 with no problems. There is a slight difference with the infinity focus between them, but I've shot countless rolls of chrome with both these lenses and find them sharp as with my other Leica lenses. Mind you that when shot at close distances and wide open, there were some photos slightly off in the focus point; though my M3 only focus' down to 3ft.

 

Regards

[john_collier2]

The CL lenses use a different cam system (simpler*) than M lenses. While many times

a CL lens will work OK with an M camera, it also possible for the CL lens not to couple

properly to the rangefinder on an M camera with a properly adjusted rangefinder.

Leica is aware of this problem and has made it known from the start of CL lens

production. I have also had this backed up by noted Leica repair people and the

personal experiences of photographer friends I trust.

 

* The CL lens cam is very demanding of the rangefinder arm's roller horizontal

position. M lens cams are not. The length of the M rangefinder arm is adjusted to give

accurate focus of wide aperture lenses through out the focus range. So different M

cameras, which will focus all the M lenses perfectly, can have the horizontal position

of the arm roller in slightly different places. This will mean that some M cameras wil

not focus accurately with CL lenses period.

[d._p.1]

thanks very much for your responses. In sum, it seems you need a slight bit of luck to have a combination that performs within limits.