Rollei 45 degree Prism Repair

ic-racer · Oct 16, 2019

I have had this 45 degree prism since about 1993. Recently it sounded loose, and the glass is rattling around.

ic-racer · Oct 16, 2019

Under the covering are 5 screws to take to top off.

ic-racer · Oct 16, 2019

With the top off, one can see there is nothing in there except the prism. No other optical elements are anything else. The prism sits freely on the base, only held in place by foam rubber.
As you can see the orange foam has deteriorated.

ic-racer · Oct 16, 2019

I cleaned the prism surfaces and fitted new foam to the top and re-attached it with the 5 screws. The covering was re-affixed with contact cement.

EdSawyer · Oct 17, 2019

Nice! Well done.

Dan Daniel · Oct 17, 2019

Very nice. Thanks for putting this up.

Question- Is there a hard reference edge in the case that puts the prism back where it was at the factory? I don't know if the final position of prism affect focus? Obviously you want the eye surface pretty close to the center of the opening, but I don't know enough about how a prism works in a situation like this to know how precisely it needs to be placed.

ic-racer · Oct 17, 2019

Yes, the prism fits in a specific location, outlined by a 2mm ridge of metal on the base plate. This ridge (indicated by the arrows) is obscured in the picture, because the bottom of the prism tapers inward. It is not a tight fit, so if the foam deteriorates, the prism shifts about one millimeter right, left and front to back. This causes a knocking sound as the prism moves around.

ic-racer · Oct 17, 2019

Dan Daniel said:
Very nice. Thanks for putting this up.

Question- Is there a hard reference edge in the case that puts the prism back where it was at the factory? I don't know if the final position of prism affect focus? Obviously you want the eye surface pretty close to the center of the opening, but I don't know enough about how a prism works in a situation like this to know how precisely it needs to be placed.

Since the ground glass is separate and fixed firmly, slight movement of the prism does not change focus at all. As with most medium format prisms, it does not show the whole frame anyway, so a millimeter shift right or left is inconsequential. In fact I tried to notice any change in the viewed image as the prism moved around but could not detect it by looking, only could tell it moved by the knocking sound.

This is crazy but this foam must have deteriorated years ago, these Rollei prisms can have a little play where they lock on the top of the camera, so for years I thought the knocking was the whole prism assembly shifting, rather than what turned out to be just the glass shifting inside the assembly.

Dan Daniel · Oct 17, 2019

Ah, nice to know the prism is indexed by a groove or lip, and then the foam acting as pressure to keep it in place.

I have taken a Hasselblad NC-2 prism and put them on TLRs (Yashica, Minolta, and Rollei), and found that I needed to set the height fairly precisely to get a focused image through the viewfinder. Still, there was maybe close to a millimeter of height variation, probably well within the receding foam holding it in place.

Pieter12 · Oct 17, 2019

ic-racer said:
Since the ground glass is separate and fixed firmly, slight movement of the prism does not change focus at all. As with most medium format prisms, it does not show the whole frame anyway, so a millimeter shift right or left is inconsequential. In fact I tried to notice any change in the viewed image as the prism moved around but could not detect it by looking, only could tell it moved by the knocking sound.

This is crazy but this foam must have deteriorated years ago, these Rollei prisms can have a little play where they lock on the top of the camera, so for years I thought the knocking was the whole prism assembly shifting, rather than what turned out to be just the glass shifting inside the assembly.

I'll have to check my prism. It rattles, but I thought that was movement around the axis since the whole unit rotates 180º. How thick is the foam you used?

ic-racer · Oct 18, 2019

I got the foam from my box of foam rubber. Looks like 10mm by 5mm.
Went to use the newly fixed prism today but I'm out of 120 film, so just ordered some from Freestyle.

sharpnikkor · Oct 19, 2019

Excellent post with some well outlined information.

I have that same Rollei 45 degree prism in both SL66 mount and Rollei TLR mount.

As far as I can tell, Rollei used that same 45 degree prism from the SL66 mount, adapted to the TLR mount, then the SLX and 6000 series,
used again with the Rollei HY6 ll and finally the Sinar HY6.

That prism design has been around for over 50 years with different mounting plates. A very well designed prism.

ic-racer · Oct 21, 2019

sharpnikkor said:
Excellent post with some well outlined information.

I have that same Rollei 45 degree prism in both SL66 mount and Rollei TLR mount.

As far as I can tell, Rollei used that same 45 degree prism from the SL66 mount, adapted to the TLR mount, then the SLX and 6000 series,
used again with the Rollei HY6 ll and finally the Sinar HY6.

That prism design has been around for over 50 years with different mounting plates. A very well designed prism.

Yes, I really like that 45 degree prism. It is brighter than the 90 degree prism. I got the 45 degree prism with my SLX and the badge reads "SLX," but when I sold the SLX I kept the prism and now use it on my 6008i. The percentage of Earth population that would be confused by the SLX label on the 6008i would likely be small.

ic-racer · Oct 21, 2019

Somewhat related, I'll have to start another thread. I'm waiting for a new Schneider Angulon PQ 40mm lens in the mail!! That old SLX Distagon 40mm does indeed work on the 6008i but it is a little cumbersome using it in 'stop-down' mode. Also, the camera won't meter in dim light with that lens in stop-down mode and dim light is where I most want to use a 40mm lens.

Pieter12 · Oct 21, 2019

ic-racer said:
Somewhat related, I'll have to start another thread. I'm waiting for a new Schneider Angulon PQ 40mm lens in the mail!! That old SLX Distagon 40mm does indeed work on the 6008i but it is a little cumbersome using it in 'stop-down' mode. Also, the camera won't meter in dim light with that lens in stop-down mode and dim light is where I most want to use a 40mm lens.

View attachment 233279

I have the 40mm Schneider and I really love it. It's small and like all the lenses I have used on the Rollei, quite sharp.

Rollei 45 degree Prism Repair

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