[vincent212]

I know removing focusing screen in the 67/6x6 was discussed on the internet but I have not found anything on how to actually remove the silver pentaprism guides. Is there a special tool for this?

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[gofour3]

Welcome to the forum!.

The 6x7/67 focus screens are changeable, but as the manual indicates it was to be done by a Pentax service rep. So yes there many be a special tool involved. Also if misaligned when changing them, will result in focusing issues.

Eric can do this for you, Eric's website:

Pentax Repairs

Phil.

[vincent212]

thank you

I was trying to see if I could tweak it instead of sending it to him.

[pentaxus]

Yes there is a special tool. More than that you can't just pop in a replacement. When you re-assemble the focusing screen you have to be able to align everything so the focus is correct across the whole screen. Don't touch any of the internal screws holding the screen in place unless you know what you are doing. Just turning a screw can lead to great sadness.

[Not a Number]

The slots on the sides of the pins suggest a lens spanner type tool would work. However as cautioned above moving these pins may change the plane alignment of the screen and or prism. Probably special equipment would be needed such as an optical bench to properly realign the screen.

[vincent212]

Yes there is a special tool. More than that you can't just pop in a replacement. When you re-assemble the focusing screen you have to be able to align everything so the focus is correct across the whole screen. Don't touch any of the internal screws holding the screen in place unless you know what you are doing. Just turning a screw can lead to great sadness.

Ok I see. Sounds a bit difficult. Although people on this forum in the past claim that they were able to do it. In any case I am not planning to go to far here. Will probably just take a look if I can remove the cover.

---------- Post added 09-24-20 at 07:59 PM ----------

The slots on the sides of the pins suggest a lens spanner type tool would work. However as cautioned above moving these pins may change the plane alignment of the screen and or prism. Probably special equipment would be needed such as an optical bench to properly realign the screen.

If I'm not mistaken the silver pins do not change the position of focusing screen. They just hold the metal plate on top of the screen in place and serve as guides for the prism. There are three additional screws underneath that control position of the screen.

[tuco]

You can optionally use a pliers with tape around those special screws (to not gouge them) you have indicated in the picture to remove them. And I would exercise caution removing them. There are small, thin brass shims under them that control the fit of the prisim/folding hoods. Once that and the shroud is removed, the focus screen can be accessed. Note the focus screen is spring loaded to press up in to its place. There is no adjustment to be made.

[vincent212]

You can optionally use a pliers with tape around those special screws (to not gouge them) you have indicated in the picture to remove them. And I would exercise caution removing them. There are small, thin brass shims under them that control the fit of the prisim/folding hoods. Once that and the shroud is removed, the focus screen can be accessed. Note the focus screen is spring loaded to press up in to its place. There is no adjustment to be made.

Thanks for the suggestions but I wasnt able to unscrew them. I cant see a way of getting them out without making a special tool for it. Sending off to Eric tomorrow.