Bronica S2A infinity focusing problem

[Bennybee]

Hi all,
A lot has been said and written on the web about this issue, and I think I have read most of it . The original focusing screen of my camera was a bit spotted and slightly cloudy on the frosted underside of the upper glass screen. I decided to replace the original combination of fresnel and glass screen by a single screen with split image from Rick Oleson : much brigher and sharper image - very happy. ...Until I ran my first test film with the new screen and noticed that everything beyond 3 metres or so seemed to require to focus the lens at infinity or almost. Furthermore, objects at infinity could not be focused properly anymore : those far away objects were split in the split image rangefinder and would require to focus the lens past the infinity mark . So back home I removed the new screen again and added some thin felt underneath it to lift it a tad : however, this increased the problem. Clearly the screen needs to sit lower -not higher- and I think I have two options to do that :
1- cut the new screen on all sides so it drops IN the VF well and comes to rest on the blade springs (like the old fresnel screen did)
2- remove the front and back rails of the VF well where the screen is resting on now, as well as removing the extremely thin shims underneath those rails (each rail is held by two tiny screws). Hopefully this will seat the screen low enough.
Yesterday I tried to clean the frosted side of the original focusing glass but without success. I guess the humidity (or mold?) has created a transparent but nevertheless slightly milky cloud in the microscopic pits of the glass.
Does anyone here have a Bronica S2/S2A please? Any thoughts on the above or other suggestions are very welcome. Thanks in advance!

[melek]

A couple of questions:

1) Have you checked the collimation of the lens? If the lens is set at infinity, is the image at the film plane also in focus?

2) Is it possible to adjust the angle of the mirror?

I probably would first check the collimation of the lens. And then once you are sure that is correct, then adjust the focus on the viewing screen.

Some cameras have a small post at the bottom of the mirror chamber that allows you to adjust the angle of the mirror, which also brings the image on the viewing screen in and out of focus.

I don't know the Bronica S2A, so I don't know if this is possible. However, this is what I would check.

[Bennybee]

Hi Mike,
Thanks for the input. I tried to check the infinity sharpness on the film plane with a piece of tracing paper in the filmgate, but I was not sure of what I saw. The image was too small and not clear enough, the paper not plane enough and my eyesight not 10/10 anymore. Ideally I would need a frosted glass or plastic, like a focusing screen cut to size and then perhaps a loupe to check that tiny telephone pole at infinity (or whatever small object at infinty).
With the original two-part focusing screen I did not have the issue that everything beyond 10ft needed focusing the lens at or near infinity. But in that case the original plastic fresnel screen -where the image is formed- was sitting a bit lower than the new one-piece Oleson screen, which is now resting where the original top glass screen was lying.
As for the angle of the mirror : I read somewhere that the S2(A) mirror hinge could sag with age although I can't see how, since the mirror sits in those side slots which it follows when sliding down during the exposure. I don't think there is a way to adjust its angle in the S2.

[melek]

Take a look at this page for instructions on how to check lens collimation.

http://elekm.net/zeiss-ikon/repair/collimate/

It's always best to eliminate as many possibilities as you can.

Have you sent a note to Rick Oleson? He's always been a very good guy. Plus, he really knows how to fix things, and he might have some advice for you.

[Bennybee]

Thanks Mike.
I sent a note to Rick Oleson and got a reply the next day! He is being very helpful and pointed out different complications that I hadn't thought off when cutting back the new screen, so I will not go that way.
I will first try to remove the front and back rails in the VF well to lower the screen a bit and see where this gets me. Since other Bronica S2 users have apparently reported the same problems, Rick is now working on another solution.
That S2 is one weird camera...

[Mike Kovacs]

If I had to guess, its probably that Rick's screen is thinner than your original and probably needs to either be shimmed, or for you to adjust the mirror.

[GrahamS]

Adjusting the mirror on any SLR system only results in a change of mirror angle, which changes the distance between the front and the rear sides of the mirror and the focussing screen differentially. If exagerated, this will produce a keystone effect on the focussing screen one way or the other, not a change in focussing distance over the entire focussing plane. If the camera produced sharp images when focussed at infinity before the focussing screen was changed, then it is reasonable to assume that the focussing surface of the replacement screen is in a different position.

[Bennybee]

Hi guys,
Extra thickness under the screen made the problem worse, so I figured that the screen needed to sit lower. I then removed the original metal rails in the front and the back of the well, but I put the four screws back in to keep the screen more or less in place - the pressure of the foam under the top frame Ould do the rest to keep the screen from twisting or rattling. I also removed the two shiny paper-thin metal (?) shims which were under the rails. And... Presto! Perfect infinity focusing now. I guess I was lucky that this was exactly right, because there is no way to lower the Oleson screen any further, it is sitting on the "bare metal" of the camera body now.
Adjusting the mirror would have been impossible without digging into the innards of the camera anyway, and I guess this would only have been necessary if the camera had been very used (which it doesn't look like) or misaligned due to sagging, which would have been obvious if the top and bottom of the image would have had different sharpness.
Thanks and all the best!

[melek]

You should post an image of how that looks. I'd be interested in seeing the camera, too.

[Bennybee]

Here are a couple of pictures of my camera. The second pic shows the camera with the complete extension ring set between body and lens.