My Polaroid 900/160 Conversion

[Ezzie]

Not easy. Adjusting the infinity stop is not a problem, but different focal lengths go from close focus to infinity at different rates. You would need to make a new cam for the rangefinder. I suspect they can be sourced from someone who knows his stuff, but if not you will have to try to make one yourself, either by trial and error or find out how to calculate the profile.

The cam is under the top plate. Mine needed recalibraring for infinity, even if I retained the original 127mm focal length.

 

[Ezzie]

Why did this thread get moved? It is about a 4x5 RF, the fact that the camera is from Polaroid has little to do with it.

 

[Hogarth Ferguson]

Did you have to cut the 4x5 back? Or did it just come apart pretty easily?

Any update on how you have been liking it?

 

[raid]

Any updates? I just saw your thread.

 

[murrayatuptown]

Old thread, but maybe someone is or will he interested in the Olympus 4x5 back.

It was an accessory for the Olympus PM-10A microscope camera.

There was a 35mm camera and a 4x5 adapter, a metal pyramidal box with relay lens to extend the image from the 35mm filmplane. The 4x5 adapter was PM-DL, and the 4x5 back was PM-C4x5. It allowed use of Polaroid, Graflex, etc. filmholders.

There was no groundglass...everything was aligned to agree with the microscope eyepiece view.

I could not copy the links on my phone, but there are several PDF manuals that show all the components of the PM-10(A) system.

You could adapt a removable ground glass screen by gluing a ground glass to spacers than mimic the film depth in a 4x5 holder...it's something like 0.196 or 0.2 or 0.223" (I don't remember).

Then on the back side of the ground glass, use add'l edge spacers to make the whole screen adapter the same thickness as a filmholders.

There is no room in the Olympus 4x5 back to have a spring-based permanent viewing screen...it wasn't needed.

So you would need to swap your spaced screen with a film holder

If you achieved the RF focus to be the same as the film plane, you don't need it, but a cruder adaptation, or different lens that presents a RF cam problem would make the screen relevant.

Murray

 

[keytarjunkie]

Wow, here's an old thread. Thank you for this info, Murray. I always wondered the history of that particular piece.

Sorry for the lack of updates. I sold the camera years ago; I found I kept reaching for the Mamiya 7 instead because I preferred the rendering of the Mamiya lens, and a field 4x5 when I wanted to really shoot large format. So it just didn't fit for me.

I think I would consider making another one of these out of the Polaroid 250 style cameras, a la Chamonix Saber, but only if I could fit a modern 4x5 lens. This requires machining a new cam, which was beyond my skills at the time. Maybe now I could figure out how to do it.

 

[raid]

Would a Land 250 be useful for such a conversion?

 

[keytarjunkie]

Would a Land 250 be useful for such a conversion?

Yup, these are ideal because they're not so expensive and have an excellent Zeiss rangefinder attached. I have one already in pieces somewhere, but I'm living abroad and haven't had access to the tools I need to start work on such a camera project.

 

[raid]

Mine is still in perfect condition, and I bought it refurbished. It was not a cheap camera. I still need to use up all film that I have for it.

 

[Forest_rain]

Wow, those pictures look absolutely fantastic! Great job!

 

[charjohncarter]

I did something similar with a Model 95. It works; here are some shots. I just used the Polaroid lens, no RF just ground glass:

$60 Polaroid Conversion by John Carter, on Flickr

Arista EDU Ultra 400 Rodinal by John Carter, on Flickr

and Type 55 Polaroid (a friend gave me a Polaroid back and some type 55):

Type 55 scan for negative by John Carter, on Flickr

 

[murrayatuptown]

Nice jobs charjohncharter & keytarjunkie.

I started conversions on various rollfilm Polaroids but I took the hinged backs completely off, rather than fight with the RF issues.

Updating a previous comment on ground glass spacer to agree with film distance when in a film holder...
on photo.net Michael Briggs 2 said:
The word is that the ANSI standard for the depth of 4x5 filmholders is a depth of 0.197 +/- 0.007 inches (e.g., http://home.earthlink.net/~eahoo/page8/filmhold.html). No doubt 0.197 inch was selected as 5.0 mm. What you really care about is the front of the film (or maybe a few thousands of an inch into the film), so allowing for this, the ground glass should be about 0.191 inches deep compared to the front of the film holder -- agreeing with the value that Diwan remembered.

 

[murrayatuptown]

There is an Olympus PM-10M Microscope attachment (adapter from 35mm camera mount to 4x5 film. No groundglass because the whole system was fixed-focus.

This is the cheapest I have ever seen one (other than the two I got free).

https://www.ebay.com/itm/255068764699?epid=1801528549&hash=item3b63487a1b:g:W08AAOSwsHNhAG58