Focus images are at slightly different angles; cannot make them completely overlap

[tom in mpls]

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I am still rather new to rangefinders, having used an M8 for a couple of months and an M9 for the last couple of weeks. Really crummy weather here so I have not had much opportunity to get out and do a lot of shooting. However I believe I have a serious problem.

 

When focusing, I generally try to locate a straight line to make it easy to get the 2 images to coincide. However, with my M9, straight lines sometimes show up slightly non-parallel. That means that if I get the bottom of the 2 images to overlap, the tops of the 2 lines diverge rather than overlap. That means I cannot make the 2 lines fully overlap. Imagine 2 straight line images, but instead of parallel one is rotated a couple of degrees from the other. That's what I'm seeing. But not all the time.

 

The test images that I have processed look fine; I seem to be getting sharp focus without back or front focus. What gives?

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[chrism]

Sounds like the camera has been bumped or dropped in shipping and now the rangefinder needs adjusting.

 

Chris

[tom in mpls]

Sounds like the camera has been bumped or dropped in shipping and now the rangefinder needs adjusting.

 

That was my logical conclusion; bummer.

 

Have others seen such a problem?

[jaapv]

That will happen if the lines are not completely in the plane of focus, i.e. they are not exactly parallel to the surface of the sensor. If your images are in focus, I think there is nothing wrong with your camera.

On focussing: There are three types of rangefinder focussing - the coincidence of lines, as you are describing, which is the simplest method, the coincidence of a pattern, which, once mastered, is the most used, and the maximizing of contrast, which is the most precise.

To the last: when you have focussed according to one of the coincidence methods, a minimal adjustment will cause the image in the rangefinder window to "snap" into maximum contrast. That is when you have achieved maximum focus.

[tom in mpls]

Aaargh.

 

Jaap, that is the issue. Of course if the top of the line is farther from the lens than the bottom of the line, this phenomenon must occur since the focus distances are different. It seems obvious to me now. I was being seduced by the seemingly simple idea that I could just focus on any line.

 

Thanks for your comments about focusing.

[richfx]

I had precisely the same experience with my 50mm Summilux ASPH (you've described it well), but not with my 28mm Elmarit ASPH or 90mm Tele-Elmarit, and posed the question to the Forum last month. Collective wisdom ruled out the M9's RF, since only one of three lenses was affected during my shoot.

I don't know, but surmise that it may have been caused by the angle of the M9 and RF to my subject, which was about 45 degrees, while shooting a pamphlet-sized book during focus testing (although, again, only one lens was affected).

The problem seems to have resolved itself (at least I haven't noticed it of late with this lens), but I made an appointment right afterwards to visit Leica in NJ with the M9 and three lenses to find out what the cause was/is, and will be there this week.

Definitely troubling, especially with a new M9. If you like, I can post the results of my visit afterwards.

Rich

[Johnny_Johnson]

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I first ran across this "problem" while photographing a car with a new Zeiss ZM film rangefinder. I was in front of the car, using the gap between the hood and fender as a target and noticed the skewed lines that you describe. My immediate reaction was that I had a rangefinder alignment problem but then, a few minutes later, realized what was really going on. I will say though that it didn't really help my confidence that I could always focus accurately under similar conditions.

 

Later,

Johnny

[richfx]

I had precisely the same experience with my 50mm Summilux ASPH (you've described it well), but not with my 28mm Elmarit ASPH or 90mm Tele-Elmarit, and posed the question to the Forum last month. Collective wisdom ruled out the M9's RF, since only one of three lenses was affected during my shoot.

I don't know, but surmise that it may have been caused by the angle of the M9 and RF to my subject, which was about 45 degrees, while shooting a pamphlet-sized book during focus testing (although, again, only one lens was affected).

The problem seems to have resolved itself (at least I haven't noticed it of late with this lens), but I made an appointment right afterwards to visit Leica in NJ with the M9 and three lenses to find out what the cause was/is, and will be there this week.

Definitely troubling, especially with a new M9. If you like, I can post the results of my visit afterwards.

Rich

[lars_bergquist]

Jaap, you are of course completely right: If the line you focus on is at a varying distance from the sensor, you cannot make all parts of it coincide in the rangefinder patch simultaneously. I have been using RF cameras since the 1950's, so this was obvious to me -- but it is not necessarily obvious to a newcomer, so you have done us a service by alerting us to this.

 

Once upon a time my wife used a work computer with the DOS 'rune stone' interface. Then she phoned me from another workface where she had to temporarily use a Mac, mouse and all. How did you move that cursor? I explained, but heard lots of huffing and groaning from the other side. In the evening, I asked her what the problem had been. "Of course it was difficult -- the mouse moved in one direction, and the cursor in the opposite one."

 

She had ben gripping the mouse front end to the rear! "But everyone knows that a mouse has its tail back and its nose front." This is not to poke fun at my wife, who is at least as clever as I am. It is to illustrate the fact that interfaces and apparatus is really not as 'self-explanatory' as some people -- people who have long known how to use them -- often suppose. The poster's problem is another case.

 

The RF is a minority camera today, and people who come to it from SLR or point-and-shoot cameras enter a very different world. Someone should write a book about basic RF technique and the different 'shooting zen' they require and also give rise to.

 

The old man from the Age of the Leica IIIa

 

P.S. In the meantime I recommend Sean Reid's new piece about 'Seeing the Subject' at http://www.reidreviews.com/ Good to have you back, Sean!

[k-hawinkler]

That will happen if the lines are not completely in the plane of focus, i.e. they are not exactly parallel to the surface of the sensor. If your images are in focus, I think there is nothing wrong with your camera.

 

On focussing: There are three types of rangefinder focussing -

 

• the coincidence of lines, as you are describing, which is the simplest method,

• the coincidence of a pattern, which, once mastered, is the most used, and

• the maximizing of contrast, which is the most precise.

 

To the last: when you have focussed according to one of the coincidence methods, a minimal adjustment will cause the image in the rangefinder window to "snap" into maximum contrast. That is when you have achieved maximum focus.

 

Jaap,

 

Thanks. Perfect!

I apologize for putting your text in bold font, but your explanation deserves emphasis, IMHO.

I wish somebody had pointed out to me your insight above when I first got my M9.

Your description certainly explains my observations, obtained in a slow gradual learning process.

The "snap" effect never fails to amaze me - when I achieve it.

When using a magnifier though, I have never experienced the "snap" effect.

 

Again, thank you so much.

 

With best regards, K-H.