Low contrast rangefinder fix

[maiko9]

I have a Zeiss Contina folder with an uncoupled rangefinder I've recently CLA'd that works beautifully, with one exception..... the contrast is so low, it's barely usable under anything other than extremely high contrast situations. I have a nice sheet of red plastic I can cut up that seems to greatly improve the situation, but I don't want to destroy the chrome finish around the eyepiece by applying it with a destructive substance. As I'm sure I'm not the only member to face this problem, can I have some suggestions for a reasonable solution?

 

[FallisPhoto]

I have a Zeiss Contina folder with an uncoupled rangefinder I've recently CLA'd that works beautifully, with one exception..... the contrast is so low, it's barely usable under anything other than extremely high contrast situations. I have a nice sheet of red plastic I can cut up that seems to greatly improve the situation, but I don't want to destroy the chrome finish around the eyepiece by applying it with a destructive substance. As I'm sure I'm not the only member to face this problem, can I have some suggestions for a reasonable solution?

Get a beam splitter mirror (used with lasers) from edmund scientific, cut it up, and replace your semitransparent mirror.

 

[Matthew Allen]

This is fairly non-invasive:

http://rick_oleson.tripod.com/index-165.html

Matthew

 

[FallisPhoto]

This is fairly non-invasive:

http://rick_oleson.tripod.com/index-165.html

Matthew

About 6 or 7 out of 10 times, in my experience, a dim rangefinder is due to some well-meaning, but inexperienced, soul who has tried to clean the semitransparent mirror. They wind up "cleaning" all or most of the silvering off of it. The only serious solution to this is to replace the mirror. The beam splitter mirrors that Edmund Scientific sells, for use with lasers, work well and the silvering on them sticks to the glass better than it does to your fingers (not usually the case with rangefinder mirrors).

 

[SteelerFan]

What should the reflectivity to transmission ratio be?
50-50
40-60
30-70
Just wondering as these are the three types of beam splitters that Edmunds sells.

 

[FallisPhoto]

What should the reflectivity to transmission ratio be?
50-50
40-60
30-70
Just wondering as these are the three types of beam splitters that Edmunds sells.

The ones I got were 50-50.

 

[Murray Kelly]

Some recommend that a quick fix is to put a clear piece of film as a neutral density filter in the direct vision side between the mirror and the front lens thus increasing the percieved contrast of the patch, which gets its view thru the other window.
I have noticed some of the old rangefinders I here have a slightly darkened viewfinder front lens by design.
Some film is crystal clear but most have a slightly grey base and that is enough to make a difference.
Hold a piece over the viewfinder as an experiment to see if the difference is enough to do what you want.
Murray

 

[SteelerFan]

The ones I got were 50-50.

Thanks. That is the one I would have tried as it seemed to make sense but it’s nice to hear that someone else actually has used them.

Some recommend that a quick fix is to put a clear piece of film as a neutral density filter in the direct vision side between the mirror and the front lens thus increasing the percieved contrast of the patch, which gets its view thru the other window.
I have noticed some of the old rangefinders I here have a slightly darkened viewfinder front lens by design.
Some film is crystal clear but most have a slightly grey base and that is enough to make a difference.
Hold a piece over the viewfinder as an experiment to see if the difference is enough to do what you want.
Murray

Thanks Murray. The rangefinder I wanted to work on is a stand alone one that had been dropped 😡 and the beam splitter was gone. This may work for a Voigtlander Automatic I have that has an extremely weak image

 

[retro]

About 6 or 7 out of 10 times, in my experience, a dim rangefinder is due to some well-meaning, but inexperienced, soul who has tried to clean the semitransparent mirror. They wind up "cleaning" all or most of the silvering off of it. The only serious solution to this is to replace the mirror. The beam splitter mirrors that Edmund Scientific sells, for use with lasers, work well and the silvering on them sticks to the glass better than it does to your fingers (not usually the case with rangefinder mirrors).

Are the Edmund beam splitters made of glass? How do you cut
them down?

 

[FallisPhoto]

Are the Edmund beam splitters made of glass? How do you cut
them down?

Back about 10 years ago, when I bought two of them there, they were glass. I still have a few small pieces of that left and have not bought any recently. I cut them with a Dremel and a cut-off disk.