This Canon Focusing Screen Y is a must-have for any photography enthusiast who is looking to enhance their film camera's performance. Designed specifically for Canon cameras, this focus screen is compatible with a range of Canon EOS cameras. With its precise focusing system, you can capture stunningly sharp and clear images with ease.

This unit quantity of 1 focus screen is perfect for those who are looking for a replacement or an additional focus screen for their Canon camera. It is an excellent addition to your camera accessories collection.

The "Y" screen is a specialized screen, offered by Canon Pro Services, that was not a catalogued item. The MIR site offers absolutely nothing regarding this screen

This screen is for the original F-1 and F-1n. It looks to be only for lenses with a focal length greater than 50mm. When used with a wide-angle lens, the view through the viewfinder is one of extreme "tunnel-like" vignetting. There is some mirror cutoff in the very upper part of the frame when used with a normal lens or telephoto. The bottom of the screen is not a matte surface like other F-1 view screens, but is crystal clear (but it has a fresnel surface). It has a large, fine-edged microprism spot that extends out nearly to the edges of the metering rectangle.

I'm guessing Canon experimented with several different focusing screens for the F-1back in the mid-1970's. They either gave these to professional photographers for evaluation, or to Canon reps who would show people these screens at camera shows.