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Problem focusing with the rangefinder


wolan

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Hi

I bought a Leica M10 (second hand) some time ago and since then I have always focused with the Visofex.

Recently, I decided to try my hand at rangefinder focusing. However, I rarely get things properly in focus. Today I put the camera with the Visoflex mounted on a tripod and indeed focusing the subject with the rangefinder looks not in focus in the EVF and vice versa. I have tried with different lenses and at different distances.

What I can do to fix the problem?

 

Thanks.

 

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Depends on how goodyou are at rangefinder focusing.

If you can rule out pilot error, you might have somebody knowlegeable look at the calibration of both camera and lens, although miscalibration is not very common these days.

 

Quote

 

Question: I come from an autofocus camera background. What is the best way to get good focus on an M camera?

 

The M works the same way as any rangefinder camera, the central patch in the viewfinder is your focusing tool.

It is important to look through the viewfinder in the optical axis. Looking into the camera skewed will result in inaccurate focus.

 

The first thing to do is to ascertain that you can see the rangefinder patch properly. A correct match between the rangefinder and your eye is even more important than it is using an SLR.

Leica sells corrective diopter lenses. Determining which one you need - if any- can be done by going to your optician and holding his try-out lenses between your eye and the viewfinder. The one that allows you to see the rangefinder patch and framelines sharply is the correct one. Order the nearest value from Leica. In a pinch you can use over-the-counter reading glasses for this test. If your eyes need special corrections, you can use your spectacles, provided you can see clearly at 2 meters distance ( the virtual distance of the rangefinder patch). Note that the background will be at background distance,so your eye should ideally be able to accommodate over the distance differential. However, there is some tolerance here.

 

For special cases there are viewfinder magnifiers. They can help, especially with longer and fast lenses and they can give confidence, but they can also be not very useful; they cannot correct errors in the focusing mechanism or your eye, in fact they magnify them.

Also, one loses contrast and brightness.

Leica offers a 1.25x one and a 1.4x. These need diopter correction like the camera, but often of a different value than the camera viewfinder.

 

There are also third-party magnifiers, sold by Japan Exposures, that include a variable diopter correction. 1.15x and 1.35x. For patent reasons they cannot be sold in the USA and Germany for use on a Leica camera, but they can be purchased for use on for instance a rifle scope.

Basically, for an experienced user, magnifiers are not needed and will only lower contrast and brightness, but some users do like and use them.

 

Once the viewfinder is corrected optimally, there are three methods of focusing, in ascending order of difficulty aka training.

 

1. The broken line method. Look for a vertical line in the image and bring it together in the rangefinder patch to be continuous.

 

2. The coincidence method. Look for a pattern in the image and bring it together to coincide. This may lead to errors with repeating patterns.

 

3. The contrast method. Once you have focus by method 1. or 2. a small adjustment will cause the rangefinder patch to "jump" into optimum contrast. At that point you have the most precise focusing adjustment.

 

Side remarks:

 

If you try focusing on a subject emitting polarized light like a reflection it may happen that the polarizing effect of the prism system in the rangefinder will blot out the contrast in the rangefinder patch, making focusing difficult. In that case rotate the camera 90 degrees to focus.

 

 

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That is what I have done, I have tested focusing on vertical edges. If I first focus with the EVF and then I look into the rangefinder window, the vertical line looks broken. On the other hand, if I then correct the focus with the rangefinder so that the vertical line does not look broken and the focusing patch it is perfect aligned, then edge does not look focus in the EVF anymore. As I said every test done with the camera on a tripod.

 

 

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I am working in Zurich (USZ). We could meet. I could tell you instantly whether your M10 needs service. I could also bring an M and a couple of lenses.

Other options: There is a Leica Store in Zürich, and also Kochphoto (Börsenstrasse 12). 

 

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1 hour ago, wolan said:

That is what I have done, I have tested focusing on vertical edges. If I first focus with the EVF and then I look into the rangefinder window, the vertical line looks broken. On the other hand, if I then correct the focus with the rangefinder so that the vertical line does not look broken and the focusing patch it is perfect aligned, then edge does not look focus in the EVF anymore. As I said every test done with the camera on a tripod.

 

 

Are you sure that you are looking into the viewfinder in the optical axis? 

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Ah, ok Yes, I am keeping my left eye on the axis the goes through the center focusing patch. The camera seems to consistently front-focus.

I have focused on the edge of a building some 5 meters away from my window using the OVF. If then look into the EVF it looks the focus on the wall of the same building some half meter from the edge I have focused on. And so the other test pictures, the focus with OVF alway lays in front of the subject I have been focusing on, no matter which lens I use (I have just tried with 75mm f2)

Thanks

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  • 2 years later...

Hello. How you fixed this issue?

I have M10. It was focusing right with 50/2. Then I bought 35/2. Everything was fine. I used non original adapter for 500mm lens. After that, I got focusing error with 50 75 90 135 lenses. Focus still OK with 21 and 35mm. What should I do?

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The most common misalignment is that you can never match the focus patch and the image at infinity position (hard stop) of your Leica lenses. I faced this problem once with my M10R: When pointing the rangefinder to a remote object, let's say a vertical pole, it was impossible to align the pole with the rangefinder patch. (It might be also possible that you can align the images, but further setting the lens to infinity position will again lead to an offset of the images.)

If you face this problem, you may (comparatively) easily fix this by yourself with an Allen key by slightly turning the excenter of the rangefinder mechanism that you see when removing the lens. I did this and it was not a big deal. I think this was discussed already in the forum. Will try to find the video...

However, if you still face a focusing inaccuracy even though the images match at infinity, things get more complicated and I would recommend contacting a Leica repair service for adjusting the rangefinder.

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