Rangefinder focus depends on which direction you turn the focusing ring: why?

[paulsydaus]

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On 8/12/2020 at 2:37 PM, Pyrogallol said:

Tricky if you use both Leica and Nikon, they focus in opposite directions !

No worse than using Leica MP and M10, with shutter speed in opposite directions!

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[jaapv]

On 8/11/2020 at 11:29 PM, FlashGordonPhotography said:

With the M240 I noticed it was less of an issue. And less again with the M10.

Which is hardly surprising. Leica tightened up tolerances to the level obtainable nowadays on the M240 and did a redesign again on the M10, making it even more precise.

[jdlaing]

3 hours ago, paulsydaus said:

I’m always a tad off infinity which usually works well for the 5m to infinity range.

Either that or zone focused further off infinity if I know I’m not going to open the aperture too much.

At most apertures you don’t need to be sitting on the hard stop to have infinity in focus plus it gives you less distance to move.

Let me clarify a little. 
 

I keep the lens on infinity while carrying so that when I bring it up to my eye I only have to turn the focus ring in one direction to focus. With practice it becomes very fast instead of hunting back and forth looking for focus. I never zone focus.

[Guest]

Am i part of some miracle?

My focus hit rate with my tele-elmarit at f2.8 is about 85%  and with my zeiss distagon 35mm at f1.4 is 90% .

On my olympus pen digital computer it was 90% on auto-focus and 60% on focus coloured peaking.

Am i the only person in the world that finds a rangefinder focus very competitive with other focus systems?

 

[adan]

50 minutes ago, steve 1959 said:

Am i part of some miracle?

My focus hit rate with my tele-elmarit at f2.8 is about 85%  and with my zeiss distagon 35mm at f1.4 is 90% .

Are you taking into account the combined effects of focal length and aperture? As well as other physical differences between lenses?

Depth of field or "focusing leeway" for the lenses you mention, compared to a 75 f/1.4, at, for example, 2 meters (6.6 feet)

75 at f/1.25 - 5.5mm
75 at f/1.4 - 6.5mm
90 at f/2.8 - 8.4mm
35 at f/1.4 - 28.5mm

The precision of a rangefinder is "fixed" in that it will deliver a certain ability to measure the distance correctly, regardless of the lens being used. The problem is that lenses of different apertures and focal lengths have different needs. A precision of ±4mm at 2m will be adequate for a 90 f/2.8, and vast overkill for a 35 at f/1.4, but marginal with a fast 75.

As it happens, I've always found the 90 TEs, especially the "thin" version, to be reliable to focus. But that is because of the limited aperture. And also that fact they are 45/55-year-old designs that are less obviously sharp at full aperture anyway - and have fairly long, damped focus throws of about 165° - and have residual spherical aberration wide-open that "spreads out" the focusing leeway for "as sharp as possible" over a bit wider range than the theoretical value listed above.

And of course, the photographer's visual acuity is a critical link in the focusing chain, as well as the individual camera's viewfinder magnification (.68x, .72x, .73x, .85x, .9x)

 

[Guest]

7 hours ago, adan said:

Are you taking into account the combined effects of focal length and aperture? As well as other physical differences between lenses?

Depth of field or "focusing leeway" for the lenses you mention, compared to a 75 f/1.4, at, for example, 2 meters (6.6 feet)

75 at f/1.25 - 5.5mm
75 at f/1.4 - 6.5mm
90 at f/2.8 - 8.4mm
35 at f/1.4 - 28.5mm

The precision of a rangefinder is "fixed" in that it will deliver a certain ability to measure the distance correctly, regardless of the lens being used. The problem is that lenses of different apertures and focal lengths have different needs. A precision of ±4mm at 2m will be adequate for a 90 f/2.8, and vast overkill for a 35 at f/1.4, but marginal with a fast 75.

As it happens, I've always found the 90 TEs, especially the "thin" version, to be reliable to focus. But that is because of the limited aperture. And also that fact they are 45/55-year-old designs that are less obviously sharp at full aperture anyway - and have fairly long, damped focus throws of about 165° - and have residual spherical aberration wide-open that "spreads out" the focusing leeway for "as sharp as possible" over a bit wider range than the theoretical value listed above.

And of course, the photographer's visual acuity is a critical link in the focusing chain, as well as the individual camera's viewfinder magnification (.68x, .72x, .73x, .85x, .9x)

 

Thanks,certainly explains why i seem fine with the 35mm distagon at f1.4.which surprised me at first.

I use the 1.4 magnifier with the 90mm and the 1.25 with the 35mm as they work very well for me on my m262[.68x].

I think its good to learn and adapt to the limitations  of the rangefinder and accept the camera type for what it actually is [ a rangefinder].