LTM rangefinder adjustment lever

[agrokid]

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As far as I can see most other makes of coupled rangefinder cameras don't have this little lever. So is it used much in practice? Would your answer be different if you had a model II with 1.0 magnification, or a model III with 1.5 magnification?

[sabears]

This was not intended as a diopter adjustment, was used to increase the precision in focusing, mainly with the 135mm.

 

cheers.

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[agrokid]

Please, "sabears", are you saying it's not really needed with a standard lens?

[sabears]

Please, "sabears", are you saying it's not really needed with a standard lens?

 

Right, with normal lens you will not have appreciable advantages.

 

kind regards.

[TomB_tx]

Actually there is a need to have this lever correctly adjusted for your eye on the LTM Leica. The IIIf manual notes: "This permits focusing on near or distant objects to the greatest possible sharpness, compensating for slight deficiencies in the eye." It is a focus adjustment for the rangefinder, and when not adjusted the rangefinder image appears blurry regardless of the lens used.

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Perhaps sabears is confusing it with the eyepiece adjustment on Canon LTM cameras, where a lever in the same position changes the magnification of the viewfinder (combined RF-VF on the Canon).

Edited September 15, 2013 by TomB_tx

[sabears]

Thank you for the photos TomB: no, I was referring to the old one, the round ocular mounted with a lever on the left rear finder. It seems to me agrokid was referring to this, as he was talking about leica II-III.

Otherwise we were talking about different things.

 

kind regards.

[TomB_tx]

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Thanks for that clarification - I had missed the reference to the II-III. I don't have a III in my collection, just a III clone (Nicca) with the lever around the eyepiece. On that the lever still seems to function like the one on the IIIc-f, as a focus for the rangefinder. I agree with a normal-wide lens you can focus adequately with a slightly blurry rangefinder, but it is nicer to have the rf sharp.

[sabears]

Just to complete, the rear lens was 1.5 x.

[payasam]

The R/F adjustment does the same work, whether it is positioned like that of the III and the IIIa on the one hand or like that of the IIIb and later models on the other. Leitz called it a focussing telescope which increased image size and therefore accuracy: and they explicitly said, in manuals and other literature, that it helped with eyesight variations and defects.

[250swb]

I don't know what you guys are looking at but the lever changes the focus on the rangefinder patch. As you change lens focus from near to far the lever needs adjusting so the rangefinder patch is clear and sharp. It is absolutely necessary for clear focusing with any lens, although the contrast of the patch is also a clue and last resort if you are in a hurry.

 

Steve

[gyoung]

On my III it adjusts the focus of the rangefinder patch to cope with my eyesight, unless adjusted the coincident images are fuzzy. It doesn't matter whether the subject is near or far, nor does it magnify the image (except as a byproduct of sharpening it). It functions just the same as the adjustment on the viewfinder of my Nikon D7000, just for sharpness (of the r/f patch in this case).

The trouble with the version on the III is that it won't stay in the adjusted position, it gets easily knocked back to horizontal when I put the camera away, which is presumably why they changed to the later version, flat on the top plate.

 

Gerry

[payasam]

The R/F image is magnified, Gerry. Please compare a II with a III or later.

[gyoung]

I think we are at cross purposes, the r/f image is magnified, but altering the adjustment doesn't change the magnification.

Its 50 yrs since I had a IIf, only have a III in LTMs now so can't compare!

 

Gerry

[payasam]

The adjustment focusses the R/F telescope, whose magnification does not vary in any meaningful way. It is called a telescope because it magnifies. The same eye will need different settings for different distances and two different eyes may well need different settings for the same distance. Because the arrangement can handle defects in vision it is now called a "diopter adjustment": which is of course incorrect.

[sabears]

The adjustment focusses the R/F telescope, whose magnification does not vary in any meaningful way. It is called a telescope because it magnifies. The same eye will need different settings for different distances and two different eyes may well need different settings for the same distance. Because the arrangement can handle defects in vision it is now called a "diopter adjustment": which is of course incorrect.

 

Agree!

[payasam]

I knew I had it somewhere. This is an extract from the Leica IIIa manual:

 

"In order to increase the ease of measuring still further, the viewing aperture of the rangefinder of the Model III and IIIa Leica is fitted with a magnifying telescope system with a magnification of about 1.5 times.... The eyepiece is adjustable by turning the milled mount, so that everyone can focus near or distant objects to the greatest possible sharpness."

 

Note that "everyone" is used, not "the user".

[chris_livsey]

What that entry does not make clear is that this is not a "one off" adjustment. An individual user will need to change it when focussing distance changes appreciably, at least I do. So unlike an SLR dioptre adjustment it is not a fix and forget.

 

My "The Leica Way" 1959 is clearer I think:-

 

" The rangefinder eyepiece has a built in magnifier which can be focussed for near or distant subjects by means of a lever below the rewind button, On older models the focussing adjustment is fitted at the back to the eyepiece itself"

 

Pg 51 illustrated marks movement from infinity, forward towards the lens to 3 feet to the rear and on early models vertical to 3 feet horizontal to infinity.

[payasam]

One has "everyone can focus near or distant objects", the other has "magnifier which can be focussed for near or distant subjects". In one place, "adjustable", and "adjustment" in the other. Neither says that the adjustment is -- or is not -- once and for all.

[Michael Geschlecht]

Hello Everybody,

 

A telescope is a form of a magnifier.

 

If you move a telescope (in which the spacing of the elements is fixed) to or away from your eye you BOTH:

 

Change the effective magnification your eye sees

 

&

 

reposition the optics so your eye can accomodate.

 

If you move an element in a telescope where 1 element is at a fixed distance from your eye & the other moves:

 

You effectively do the same thing.

 

Best Regards,

 

Michael

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[chris_livsey]

One has "everyone can focus near or distant objects", the other has "magnifier which can be focussed for near or distant subjects". In one place, "adjustable", and "adjustment" in the other. Neither says that the adjustment is -- or is not -- once and for all.

 

As I said above: "An individual user will need to change it when focussing distance changes appreciably, at least I do"

 

I am not a manual or guide but I definitely need to change the setting on my IIIc/f when viewing near then distant objects to obtain a clear image. The patch is usable without but for accuracy a sharp image is preferable.

The magnification/image size does change, slightly, much as an SLR on a tripod will change as the edge of the frame changes on the screen as the lens is focussed. It is there but not significant and is more noticeable at close distances.

 

Returning to the OP "Is it much used in practice?" Actually in my case no because my work is at middle distances, mostly, but if I use a close up shot, here meanig 3 to 5 feet I will change it.