Lens or rangefinder calibration m10r

[Kiran]

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How do you determine if a lens is out of calibration or the rangefinder?

thanks

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[Gobert]

With a 2nd lens

[Kiran]

17 minutes ago, Gobert said:

With a 2nd lens

How would you know the 2nd lens is calibrated?

 

[pippy]

Take both body and lens to a dealership.

Philip.

[Photoworks]

you can set lens scale to  2m distance and measure 2m from your subject to the sensor plane.

Should be in focus at 1.4 or f2.

If it is in focus in the rangefinder but not in Live View then it is probably the lens.

I needed the sensor calibrated on the M10P, I was not able to focus at infinity at 1.4, sent it to leica and every was wonderful in a few days.

[Gobert]

9 hours ago, Kiran said:

How would you know the 2nd lens is calibrated?

 

With the third one of course

[Matlock]

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Just now, Gobert said:

With the third one of course

And then a 4th, 5th, 6th, etc etc.😃

[Rob L]

If you look through the viewfinder and focus on something very far away, your images should coincide when lens hits the infinity lock. If this happens you are 99% assured to be in adjustment. Oversimplified, but true!

[Kiran]

7 hours ago, Rob L said:

If you look through the viewfinder and focus on something very far away, your images should coincide when lens hits the infinity lock. If this happens you are 99% assured to be in adjustment. Oversimplified, but true!

The lens or camera?

[jdlaing]

Mount a lens an shoot something 6-8 feet away.

Mount the second lens and do exactly the same.

If both photos are not focused it is the rangefinder mechanism. If one photo is focused it is likely the other lens.

[Kiran]

So if a lens is locked to infinity and the rangefinder shows a distant object properly aligned but the image comes out blurred, ie. focused beyond infinity.
Would that be a lens or body issue? 

[jdlaing]

1 hour ago, Kiran said:

So if a lens is locked to infinity and the rangefinder shows a distant object properly aligned but the image comes out blurred, ie. focused beyond infinity.
Would that be a lens or body issue? 

How distant is the object?

[jdlaing]

And is it the same with a second lens?

[Infantasy]

If you know the construction of a lenses and its focusing mechanism vs the focusing mechanism of a rangefinder then you may agree that the possibility of having a focus drift on a lenses is not that easy while a rangefinder is more vulnerable on the contrary.

I would compare the focus accuracy between the optical focusing and the peaking on live view. 

[Kiran]

1 hour ago, Infantasy said:

If you know the construction of a lenses and its focusing mechanism vs the focusing mechanism of a rangefinder then you may agree that the possibility of having a focus drift on a lenses is not that easy while a rangefinder is more vulnerable on the contrary.

I would compare the focus accuracy between the optical focusing and the peaking on live view. 

Comparing the optical to live view the out of focusness is visible and turning the focus back slightly from infinity will render the image back to peak sharpness.( however the rangefinder will now be misaligned)

The distant object is over a mile away. 

[Guest BlackBarn]

As a non techie -  Can anyone tell me what the difference is between optimizing a lens to a camera and calibrating a lens/camera.

I am in discussion with Leica through our NZ Leica rep regarding optimizing a lens with my M cameras.

This is the reply they received:  ‘They (Leica Germany) advised that it is always recommended to optimize all lenses to your camera. It is possible that if they will optimize your camera with only the 50mm lux, some other lenses will not focus perfectly on the camera anymore and needed to be optimized too’

[Gobert]

31 minutes ago, BlackBarn said:

As a non techie -  Can anyone tell me what the difference is between optimizing a lens to a camera and calibrating a lens/camera.

I am in discussion with Leica through our NZ Leica rep regarding optimizing a lens with my M cameras.

This is the reply they received:  ‘They (Leica Germany) advised that it is always recommended to optimize all lenses to your camera. It is possible that if they will optimize your camera with only the 50mm lux, some other lenses will not focus perfectly on the camera anymore and needed to be optimized too’

I have two bodies… optimization is not possible?

[JonPB]

For a rangefinder camera to focus accurately, both lens and camera must agree on what indicates nearest, what indicates infinity, and the curve that plots all points in between. This is because the rangefinder, unlike a view camera, SLR, or EVF camera, does not inspect the lens’ image directly to evaluate focus. Instead, one mechanism gauges distance to subject (the wheel at the top of the shutter box and the mechanics it attaches to in the camera, and the ring that moves in and out of the inside of the mount of the lens), and an independent mechanism adjusts the lens to focus at that distance (the distance between sensor and lens mount in the camera, including film plane flatness where relevant, and the movement of the optical cell(s) relative to the mount in the lens). Both systems must agree in box camera and lens to achieve optimum focus.

This is a surprisingly complex problem. Possibilities that come to mind for a system that focuses past infinity in the center of the frame include:

It might be working as intended. The lens might have field curvature and the lens designer optimized it to attain maximum resolution, i.e. to be in focus, in a ring around the center of the image, not the axis or corners. With recent lenses, you might look at the MTF curves; in the curve for the appropriate aperture, if the lowest dashed/solid pair of curves slopes upward from the left edge before falling down toward the right edge, then this behavior can be expected (but is unlikely to be visible when viewing the full image).

It might be working as intended, part two: the lens was calibrated to place focus in the middle of the thickness of a sheet of film, but it is being used on a digital sensor which does not behave as if it has thickness. In this case, the lens is effectively focusing behind the sensor, so focusing closer (moving the lens away from the sensor) improves resolution.

It might be working as intended, part three: all lenses have aberrations, some of these aberrations occur mostly in front of or behind the focus plane, and some of those are reduced when changing aperture. Removing aberrations in front of the focus plane will shift optimum focus backwards without changing actual focus at all. Designers of lenses with this focus shift behavior must choose which aperture the focus setting is optimized for.

It might be working as intended, part four: our metal lenses are more responsive to temperature changes than a well-designed plastic housing, so hot or cold temperatures have elongated/constricted enough material to change focus. I haven’t heard of this in practice, though; or, if it has changed enough to alter focus, the photographer has more pressing issues.

It is working as intended, part five: your demand for focus has exceeded the design specifications. This may well be expected of extreme lenses: 135/3.4, 90/2, 50/1.2 lenses or with wider aperture might be within allowable tolerances yet still not perform well together. Changing both or either might improve performance in that equipment pairing yet impair performance of the calibrated device with most other M systems.

Neither are working as intended, but they both agree with each other, mostly. To make the system work, all M lenses and cameras are designed to align within a given tolerance of a certain specification. But the spec doesn’t matter so long as the parts interacting do so agreeably. This is why testing multiple items helps identify the problem: if you have lens A, lens B, and camera 1, and two of them agree with each other but not the third, most likely the third would benefit from calibration.

The camera is miscalibrated for focus throw: the shouldn’t be a problem at infinity, but might be at any other distance.

The camera is miscalibrated for infinity: all properly calibrated lenses tend to show the same error. Adjusting camera will improve its performance with most lenses.

The lens is miscalibrated for focus throw: some lenses have been modified by people who didn’t understand the system; sometimes this can be fixed by rotating the modified part out of the way.

The lens is miscalibrated for infinity: as above or can be adjusted with shims.

The camera and/or lens are misaligned. This can be expected with devices that show significant dents, and also when using imprecise adapters. 

So, there can be no generic answer to satisfy this kind of problem. It is not uncommon for rangefinder shooters to learn that lens a at aperture b needs to be adjusted like so when working at distance c, and so forth. I know that this is not a satisfying answer, but it is part of the package deal when extracting such high image quality from mechanical devices of this size.

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[Infantasy]

You may refer to the attached post to understand the focusing mechanism of a rangefinder then adjust yourself. To my experience,  use a long lenses, e.g. 90mm, to calibrate is more effective.  Don't use wide angle lenses.

 

[jaapv]

This is  the very reason that technical services, including Leica, prefer to have the complete system sent in, not just a single lens or body. The lenses and body will be adjusted separately to a common standard. On very sensitive lenses, like a  Noctilux, there  may be tolerance matching between lens and body.