Using a 135mm lens on a Leica IIIF

[AnthonyM]

I just purchased on line, a 135mm Leica Screw mount lens for my IIIF. It will take about a week to get here. In the mean time, I was wondering how the camera knows it has a 135mm lens on it. Is there a cam or something that connects it to the rangefinder, allowing me to focus correctly? Or, do you zone focus? I plan on getting a 135mm bright line finder from Steve Gandy so I can at least get an idea of what will be on the film.

 

[FPjohn]

A following lever-roller in the IIIf body, you can see it by looking in the body lens mount , adjusts the rangefinder to a specific cam on each lens.

yours
FPJ

 

[Luddite Frank]

As long as the lens is RF-coupled, the mount is standardized; there's no (functional) difference from one focal-legnth lens to another as far as the integral Leica rangefinder is concerned.

If you have an LTM lens off the camera, thread-mount facing you, there is either a tab or a ring that projects from inside the mounting-ring, that retracts into the lens barrel as you focus "closer" from Infinity. This in turn, operates that lever-follower in the body that FP John mentioned.

Except for the III-g (?) there are no frame-masks or the like that are deployed by the different focal-legnth lenses.

The M-cameras were the first Leicas that "knew" (or "cared") what lens was mounted.

From the Leica-II (1932) onward, all LTM RF-Leicas have the same standardized Lens / RF interface.

Leica considered 135mm to be the longest focal-legnth practical on an RF camera, due to the increasingly shallow depth of field with the longer lenses. For lens longer, Leica made them only for use with the Visoflex Mirror-reflex housing, which essentially turned the Barnack into a cumbersome SLR.


My 1950's Hektor 135 has a very shallow DOF at minimum focus ( 5 ft) at full aperture (f:4,5): less the one foot either way...

Set at 300 ft on the scale, at f:4,5, DOF covers 100 ft to Inf.


Luddite Frank

 

[AnthonyM]

Thank you gentlemen.

 

[polaski]

The IIIf may not "know" the focal length of the lens you are using, but it orobably knows other things about you, so be discrete.

Or, put the lens on the camera and see what it does.

 

[payasam]

If the lens has R/F coupling, you're set: 135 mm is too long for zone focussing except at considerable distances.