Mamiya RB67 CDS Prism Finder on RB67 Pro SD

I need some help with this one... I bought a RB67 CDS Prism Finder on ebay. Everything works, but the image through the prism is blurred when the prism is mounted and looking through the lens. Looking through the prism off the camera, the image is perfect. The image through the WLF through the lens is perfect. Does anyone know if the CDS Prism can be used on the SD body, or what the problem may be? I looked at Bob Shell's book, and the system chart for the Pro S shows the CDS Prism. The system chart for the Pro SD does not. THANKS!

Does the prism have it's viewfinder lens? The only time I've ever seen this happen it was missing. Where you look into the prism should have glass right to the edge of the frame - if it doesn't you need to contact the seller that it's faulty

I am not aware that there could be a difference between S and SD concerning the finder. I think there is a problem with the optics of the prism finder itself.

Edit: Do you want to share an image of the finder?

Joachim

I suspect that the prism either has been dismantled by unskilled labour who has tried to clean it internally and re-assembled it without the components being in proper optical alignment, or it's been subject to shock damage that has displaced some of the internal optics, either way it needs some professional attention.

Another possibility is that there are diopter correction lens that fit the Mamiya prisms. Perhaps your prism has one installed.

There are little red dots on the bottom left edge that indicate the diopter correction. IE, one red dot equals one diopter, two red dots equals two diopters etc.

JD

According to the copy of the instruction manual for the Mamiya RB67 CDS finder that I have, there is a "Visibility adjusting ring" at the base of the eyecup.

Have you adjusted the visibility?

Thank you all for you help! I think Andrew K hit it on the head. It looks like the focus lens is missing. When I look in the eyepiece I can see the exposed edges of the CDS cells and then there is solid glass which I assume is the prism itself. The distance from the frame to the glass is about 1/2 inch. I wonder if it may have come out in shipping, or does the finder have to be disassembled to remove it? I did not see it in the box. Nonetheless, I will be returning the prism. I'm a newcomer to the RB67 and was surprised the prism was so heavy. I may look for a chimney finder instead. I assume it's less than half the weight of the prism. I'd be interested in your experience with the CDS chimney finder. Thank you again...