Leica M 50 & 35 Summicrons Focus Rings at Infinity and Horizontal Alignmentr

[RayD28]

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I have both lenses and use them on an M9.  When I focus objects at 100 meters away at infinity using the viewfinder I get the horizontal lines lined up just just before the focus ring is fully turned.  In other words, if I turn the focus until it stops and then look at the viewfinder my subject at 100 MM is not perfectly aligned.  I then back down the ring away from infinity ever so slightly and then the image is perfectly aligned.  Is this common with my setup?  

 

I'm going to shoot some test shots tonight but in the meantime I'd like to know if anyone else experiences the same thing.  

 

Thanks.  

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[michaelwj]

How much by?

100m is about infinity meters shy of infinity

Jokes aside, try the moon (not the sun) and see how that works. At least something farther away that 100m.

 

Michael

[dem331]

^{I have both lenses and use them on an M9.  When I focus objects at 100 meters away at infinity using the viewfinder I get the horizontal lines lined up just just before the focus ring is fully turned.  In other words, if I turn the focus until it stops and then look at the viewfinder my subject at 100 MM is not perfectly aligned.  I then back down the ring away from infinity ever so slightly and then the image is perfectly aligned.  Is this common with my setup?}  

 

^{I'm going to shoot some test shots tonight but in the meantime I'd like to know if anyone else experiences the same thing.}  

 

^Thanks.  

 

 

I had this problem with a 50mm summicron and when I ran some tests (with and M8 back then) I realised that the lens was not focusing correctly at middle distances (10 to 30 meters).  Had it CLAd and problem solved.

 

If it is happening with both lenses, chances are that it is the rangefinder.

[semi-ambivalent]

For adjusting the RF with a 50mm lens I've seen a quarter mile suggested. Like a distant TV tower. Leica's RF can certainly discern 100m from infinity. But "horizontal" lines? Do you mean vertical? Or is the camera being held vertically? These are two different alignments, set by two different screws. Parallax adjustment is happening as well when you focus.

 

s-a

[RayD28]

For adjusting the RF with a 50mm lens I've seen a quarter mile suggested. Like a distant TV tower. Leica's RF can certainly discern 100m from infinity. But "horizontal" lines? Do you mean vertical? Or is the camera being held vertically? These are two different alignments, set by two different screws. Parallax adjustment is happening as well when you focus.

 

s-a

 

I meant to say vertical lines.  Handheld.  f2.8.  1/250th.  ISO 400.  I'll try the TV tower at 1/4 mile and some flag pole at 10 M and use a tripod, 160 ISO, and f2.8 and f5.6.  

 

By the way, are we saying focusing on an object at 100M would not put everything in focus that is beyond 100M even if the lens indicates 100M is infinity?  Sorry if that's an ignorant question.

 

Appreciate advice.  

[RayD28]

Did some tests shots and then some reading about depth of field.  I now understand that a 50mm lens on a full frame shot at 2.0 with subject at 100M does not include infinity in depth of field.  Here is a link to a depth of field calculator that is helpful.

 

http://www.dofmaster.com/dofjs.html 

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Did some tests shots and then some reading about depth of field.  I now understand that a 50mm lens on a full frame shot at 2.0 with subject at 100M does not include infinity in depth of field.  Here is a link to a depth of field calculator that is helpful.

 

http://www.dofmaster.com/dofjs.html 

However, this dof calculator seems to say that the DOF for a 50mm lens at f/2.0 will extend to infinity for a subject distance of 100m.

[jaapv]

Did some tests shots and then some reading about depth of field.  I now understand that a 50mm lens on a full frame shot at 2.0 with subject at 100M does not include infinity in depth of field.  Here is a link to a depth of field calculator that is helpful.

 

http://www.dofmaster.com/dofjs.html 

Depth of field is not an exact value. Nor is  everything in focus within DOF. It is an acceptable zone of unsharpness which depends amongst other on magnification, sensor/film resolution and acuity, subject matter, subject contrast and tolerance level of the photographer.

The sharpness is not equal throughout the zone of DOF but increases gradually to the plane of focus and decreases gradually behind it.

Thus a photograph is sharp ONLY in the plane of focus. If you want the horizon tack sharp, you must focus on the horizon.