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How can 135mm frames be so inaccurate?


pico

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Leica M9. 135mm Hektor M mount. How can 135mm frames be so inaccurate? They cut off

about 20% of the top at minimum focusing distance which is a bit short of five feet.

 

It is not terribly important to me because I rarely use the thing. Just curious.

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M9 frame lines are optimized for 1m, while the M240 and M10 (and M8.2) lines are optimized for 2m.

 

Jeff

Thank you. The 135mm Hektor has minimum focus at some unmarked distance closer than 1.5 meters. No problem. I can compensate or put it on the shelf. :)

 

I should add that the RF is accurate at minimum distance!

Edited by pico
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The same principle of course applies to all focal lengths, and is why I lobbied here for a return to the 2m frame lines after the M9, since that better accommodates my shooting style. One can always learn to adapt, but it's nice to get it close from the start.

 

Jeff

Edited by Jeff S
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Of course I didn‘t measure it, but I am rather sure that the frames for 135mm are not calibrated to 1m for the M9 but - as originally for all lenses - to the shortest focus distance, which is 1.5 m. There is no M lens with 135mm which focusses to 1m, so calibrating the frames for this distance would make no sense.

 

If they really were calibrated for 1m, the frames would show more than the picture taken at minimum focus. pico was complaning about getting less. May be the problem arouse because he was able to focus the Hector a little bit closer than 1.5m - then you really get less on the picture by a whisker.

 

When I have time I‘ll try on a tripod, also if there are differences between the M9 and M10 for 135mm - which should be the case.

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Short version: Probably some play in an older lens**, especially one with a long tube and higher mag. factor. And/or some inadvertent shift in camera pointing when pressing the shutter button.

 

I began noticing about 2 years ago that my 135 Tele-Elmar (1969 build) seemed to be aiming "down and to the right" significantly with my M9 - probably close to 10-15%, maybe 20%. I determined that 1) there was some play in the old barrel/mount, and 2) that pushing down on the top of the shutter button front-right on the camera tended to produce a down-and-to-the-right camera movement. Especially with a long 135mm tube dangling off the front.

 

I began being more careful with handling the camera with the 135 - pulling the lens in tight against the mount, and being more careful to "squeeze" rather than push the shutter button. Problem went away.

______________

 

Short, short version: Pico, like me, you are getting old and shaky. Be a bit more careful with lens/camera holding and shutter release, especially with a 135! ;)

______________

 

Longer version: As we know, lenses change field of view slightly (or even more than slightly - scales with focal length) when focused at various distances. With fixed mechanical frames, the framelines will only be "perfect" at some one distance. At long distances we get more in the final picture than the frames show, and at very close distances (especially with the 2m optimization) we get less than the lines predict.

 

Leica even provides instruction-book guidance on this effect, and how to correct for it visually: https://d1ro734fq21xhf.cloudfront.net/attachments/003xIq-10016784.jpg

 

RTFM!

 

The optimized framing distance Leica chooses has changed over the years, from accurate at minimum focus (0.7m for a 75 or wider on film M6), to 1m, to 2m, to perhaps even 2.5m with the M10 (per my experience). Mostly because in the film era, slide mounts or negative holders "cropped" the image on the film as finally seen in a print or projection, whereas with digital, we get the whole 24mm by 36mm image area all the time. People began to notice and complain about getting "too much" in their final pictures.

 

I love this change, because it gives better accuracy at most and longer distances - but it does increase the chance of cutting things off at closer distances.

 

Additionally, Leica RFs always suffer from some parallax error, except using LV/EVF (recent development). By definition, the lens is seeing the world from a different point than the viewfinder and your eye, approximately two inches down and to the right. The frames move with focusing to compensate for this to some extent, but it's always approximate, especially given that the finder/movement has to average out the effect for all lenses from 28mm to 135mm.

 

I'm noticing framing difficulties again with the 75 Summarit f/2.4 on the M10 - probably because 1) the Summarit is ultra-light and thus again prone to move with shutter release or shake again (less mass), and 2) it now focuses really close (0.7 meters) so the final pictures are substantially cropped compared to the M10's 2/2.5m optimized framing distance. I just pay attention more.

_________________________

 

** in college, the lab had some old-beaten-up loaner lenses, one of which was perhaps the world's only "200mm PC-Nikkor-Q." The long barrel was so loose that you could wiggle it and see the image on the ground-glass move up, down, and sideways. You had to hold the lens steady on the camera as well as holding the whole package steady - or, "Tilt!"

 

Not that specific example - but the old "stovepipe" Nikkor-Q: https://www.picclickimg.com/d/l400/pict/322632006680_/Nikon-Nippon-Kogaku-NIKKOR-Q-200mm-f4-Lens.jpg

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I fear, we are making the issue more complicated than it is.

 

  • If a lens - especially a long one with an optical system far away from the sensor  - was fixed in any wrong angle to the body, it would be horrribly decentered. No focussed images possible. Pico said that the focus was good, just the frame was too small.
  • An ever so little movement  with a long lens has a much bigger impact than with a short one. Tripods were made to avoid this.
  • Viewfinder frames don't change by focussing, they are calibrated to a certain focussing distance. In this distance they are exact. With longer distances they are too small, with shorter distances they are wider than the actual picture result.
  • If the frame for 135mm was calibrated to a distance of 1m - even though you cannot focus any 135mm M-lens to 1 m - the frames would always be too small - never too wide.
  • Only if the frame was calibrated to more than 1.5m - say 2m as for the M10 - it could become too wide when you focussed it at it's minimum distance.
  • Since especially older lenses had very long focus throws, the real closest distance could go somewhere below the nominal value of 1.5m - making the frames a little bit too wide if they were calibrated to nominal closest focus distance - which was the traditional way before the digital cameras with their displays made users fuzzy about their frames.
Edited by UliWer
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It's not completely easy to try it out, since one has to use  a lot of guessing, where the little frame for 135mm is exactly. In all exables the upper left frame corner was on the vertical black stripe, the lower right corner at the horizontal black stripe.

 

Comparison between frames and results probably were closest for the M9 with a 135mm Apo-Telyt at a distance of something less than 170mm - say 168mm:

 

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With the M9 and an ancient 13.5cm Hector at something more than 170mm - say 172mm (the difference is perhaps due differences in real focal length or just in the scales).

 

 

 

 

 

 

And for the M10 - again with the Apo-Telyt: at something less than 170mm - say 168mm:

 

 

The differences between the example from the M10 and the M9 was mainly caused by the M10 directed to the target a little bit lower than the M9.

 

 

 

So I'd say: the frames for 135mm are calibrated for the M9 and the M10 at the same focussing distance of approx 170mm - certainly more than 150mm and certainly less than 200mm and of course not 1m for the M9.

 

 

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Before the M240 I used a Leitz brightline finder for 135, those are calbrated for accuracy at infinity, with parallax correction tilt and tickmarks for field size at maximum extension. With the M240 I mostly use EVF. I can compensate the finder framelines from experience, but the tiny area is more difficult to compose with.

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If you enjoy film, then consider using an M3 where the 135mm frame lines are quite reasonable in size. I have had accurate framing results (within my expectations) with both a 1961 Elmar-M and a 2015 Apo-Telyt-M using two M3's.

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