Strange mark on Summitar/Summicron

[marke]

Advertisement (gone after registration)

I have a 1946 coated 50/2 Summitar. I've been wondering three things about the markings on it.

 

First, can anyone tell me what the "R" in the middle of the DOF scale is supposed to mean? Possibly just "reference"?

 

My second question is what the diagonal short black line is that seems to point to the #2 mark on the scale.

 

And my third question is a small screw or pin that seems to lay in the middle of that line for #2. Anyone know what this is?

 

The first picture shows my Summitar, and the second picture is of an early collapsible Summicron when Leica was using Summitar barrels. The diagonal line and screw/pin is on both models.

 

BTW, I was thinking about picking up one of these early collapsible Summicrons in M mount, to use on my M3. But I'm wondering what others might think of how this lens compares to the Summitar, and whether the early 'cron would be a significant improvement over the 'tar.

 

[Advertisement]

The Leica Q3 is available for pre-order at B&H Photo Video and Adorama

[rubenkok]

First, can anyone tell me what the "R" in the middle of the DOF scale is supposed to mean? Possibly just "reference"?

 

My second question is what the diagonal short black line is that seems to point to the #2 mark on the scale.

 

And my third question is a small screw or pin that seems to lay in the middle of that line for #2. Anyone know what this is?

 

Hi Mark,

R and line indicate the R at f/2

R @ f/2 is the index for use with infrared film

Here is another: Leica 135mm f/4.5

 

Most manual focus 35 mm SLR and medium format SLR lenses have a red dot, line or diamond, often with a red "R" called the infrared index mark,

that can be used to achieve proper infrared focus; many autofocus lenses no longer have this mark.

found at Infrared photography - Wikipedia, the free encyclopedia

 

hope this is some help.

regards

Ruben

[doubice]

I have a 1946 coated 50/2 Summitar. I've been wondering three things about the markings on it.

 

First, can anyone tell me what the "R" in the middle of the DOF scale is supposed to mean? Possibly just "reference"?

 

My second question is what the diagonal short black line is that seems to point to the #2 mark on the scale.

 

And my third question is a small screw or pin that seems to lay in the middle of that line for #2. Anyone know what this is?

 

 

Hello Marke,

 

The 'R' is a focusing mark for infraRedfilm. When using infrared film, the focus plane has to be shifted and many older lenses had this mark. Basically, you focus the camera through the rangefinder as usual and than re-position the focus point to the 'R' mark.

 

The 'diagonal line' simply points to the indicator of where the 'R' line of focus should be.

 

The small screw has nothing to do with the above and probably is used to adjust the focusing mount or the focusing scale.

 

Best,

 

Jan

[marke]

Ruben and Jan, thanks for answering my question. I don't know why I never considered it to be an infrared focus mark, but that makes sense. It just didn't occur to me that the R had any relation to the diagonal line, because when I first found the line I just though it was a "typo" by the engraver. Then when I spotted it on the Summicron, I figured it was actually significant!