[stevebrot]

I am not sure just how that would work since my memory is that top of the mount is spring-loaded to provide tension and don't really want to fiddle with my camera to confirm

Well! I spent some time (too much) looking at my camera and the installation JPEGs for various Pentax models on the Katz Eye Web site and low and behold, the spring-loading is on the retainer frame with registration being set by the upper (fixed) part of the frame assembly. That being the case, screen thickness would be critical per the comments above with screens possibly requiring shims between the top surface of the screen and the fixed portion of the mounting frame. I will revise my earlier comments.




Steve


* it is unclear what action could be taken if the new screen is overly thick (front-focused)

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Last edited by stevebrot; 01-21-2014 at 12:38 PM.

[mrNewt]

...

* it is unclear what action could be taken if the new screen is overly thick (front-focused)

I doubt if that was ever the problem... at least I have never heard anything about an issue like that.
The area where the focus screen is sitting in is "deeper" on purpose and as far as I know, all cameras are coming with shims on their stock focus screens - and they are usually on spot.

Again, as far as I know (and I'll stand corrected if I am wrong), all these aftermarket screens are actual re-cut focus screens that were originally built for film cameras. And they are using a wide variety of brands... since the different thicknesses for different types.

If there are actual companies that are building aftermarket screens from scratch dedicated for specific cameras, I guess they would choose the right thickness so you won't need to change the shim.
However, personally I am not aware of any company that actually does that though (obviously I could be wrong)... maybe Katz Eye does it since they seem to be the most expensive.

[stevebrot]

I doubt if that was ever the problem... at least I have never heard anything about an issue like that.
The area where the focus screen is sitting in is "deeper" on purpose and as far as I know, all cameras are coming with shims on their stock focus screens - and they are usually on spot.

My thoughts as well, though I would mention that my K10D was not shimmed. Current cameras may all be shimmed for all I know.

Again, as far as I know (and I'll stand corrected if I am wrong), all these aftermarket screens are actual re-cut focus screens that were originally built for film cameras. And they are using a wide variety of brands... since the different thicknesses for different types.

If there are actual companies that are building aftermarket screens from scratch dedicated for specific cameras, I guess they would choose the right thickness so you won't need to change the shim.
However, personally I am not aware of any company that actually does that though (obviously I could be wrong)... maybe Katz Eye does it since they seem to be the most expensive.

Most aftermarket screens are, as you said, cut-down versions of readily available screens originally intended for use with the 35mm format. The one exception might be the Katz Eye product. Despite similarities to the Nikon K-3 screen, Katz Eye maintains that their products are fabricated by them and are not repurposed screens from other makers. That may explain why they do not supply shims with their screens. Perhaps their screens are made to the same thickness as the Pentax original. Katz Eye does offer screen installation as a service ($65 USD) during which they will calibrate the manual focus if needed.


Steve