Voigtlander Bessa RF (6x9) - Tried to vertically align the rangefinder, but. . .

[Peter G-falk]

Hello anybody that might be interested in old folding cameras and if you might have any type of information to share on this thing that happened to my Bessa today, I'd be very happy to hear your ideas.
I took the top cover of the camera off, I had found out what screw to manipulate to vertically align the two rangefinder sections, so that if the correct focus distance was set, it would show only one single image. Not like it was in my camera, one quite a bit above the other one.
I put the camera on a tripod and looked through the rangefinder eyepiece and turned the screw. How ever, I could only see one image. Not the two that I wanted to merge. So I thought I'd at the very least blow some dirt and dust away. What came loose was one of the small prisms inside the rangefinder. Luckily, I found it again and tried to find out where to put it back again. I'm still not sure and made a little video presenting the problem and showing it (hopefully) more clearly than I can do in just words here. Please have a look and see if you might be able to help me get this old camera back to life again.

 

[Alex Varas]

Next week I will open same model for adjusting the vertical as well. I will post photos.

 

[Dan Daniel]

Based on the black paint on the ends of one face and the black paint on the upper prism, looks to me as if the loose prism slide under the upper prism and you have it oriented. I am not familiar with this prism setup but it does remind me of the Kodak Medalist system. In that case, the two prisms create a true split, meaning and upper and lower image. Not a convergent image like your image in the beginning shot. So consider if this is the actual system- two images stacked on top where one side moves left to right and 'focus' is when they converge- a vertical line in the top image continues into the bottom image. It is by adjusting the mirrors feeding this system that you adjust the vertical position of the images. So the top and bottom image are continuous. Looking at a triangular shape will make this clear.

Not certain if there needs to be a tight cemented joint between the upper and lower prisms. On the Medalist thisis a cemented pair and the line between the two images gets ugly if this joint fails. But I wasn't seeing the top of the loose prism showing signs of an optical joint.

Well, I could be very wrong about all of this, just extrapolating from other cameras (Kodak Chevron has something similar but there is a small area of convergence where the top and bottom image meet, so you have both- a true split with a thin band of convergence).

 

[Alex Varas]

I have found a photo of a Bessa RF I did years ago.

 

[Peter G-falk]

Next week I will open same model for adjusting the vertical as well. I will post photos.

Sounds GREAT!

 

[Peter G-falk]

Based on the black paint on the ends of one face and the black paint on the upper prism, looks to me as if the loose prism slide under the upper prism and you have it oriented. I am not familiar with this prism setup but it does remind me of the Kodak Medalist system. In that case, the two prisms create a true split, meaning and upper and lower image. Not a convergent image like your image in the beginning shot. So consider if this is the actual system- two images stacked on top where one side moves left to right and 'focus' is when they converge- a vertical line in the top image continues into the bottom image. It is by adjusting the mirrors feeding this system that you adjust the vertical position of the images. So the top and bottom image are continuous. Looking at a triangular shape will make this clear.

Not certain if there needs to be a tight cemented joint between the upper and lower prisms. On the Medalist thisis a cemented pair and the line between the two images gets ugly if this joint fails. But I wasn't seeing the top of the loose prism showing signs of an optical joint.

Well, I could be very wrong about all of this, just extrapolating from other cameras (Kodak Chevron has something similar but there is a small area of convergence where the top and bottom image meet, so you have both- a true split with a thin band of convergence).

Thank you for a very interesting answer Dan Daniel. I will certainly look into this for a solution. I especially like your explanation of the two-prism system for how this rangefinder might work. Certainly makes the system with two prisms seam much more reasonable all of a sudden. Thanks again.

 

[Alex Varas]

Here it goes.

 

[Peter G-falk]

Here it goes.

View attachment 344879

Great shot! Thanks for posting it.
I just wonder how, and to what it was fastened? Glued to the surface underneath or to the prism on top?

 

[Alex Varas]

Only one image was moved by the vertical screw so it makes sense the lower prism is glued underneath but I can't know for certain. Camera is back to client.

 

[Peter G-falk]

Only one image was moved by the vertical screw so it makes sense the lower prism is glued underneath but I can't know for certain. Camera is back to client.

Thanks!
Gluing it to the surface underneath, is what I'll try first of all...