Going for a Stage 2 mod ..

[Merlin]

Is it possible to do a PST stage 2 mod without the need for a centre lathe? Can the mod be done using already existing bits'n'pieces cobbled together?

[Merlin66]

Yes and no.....

It involves using a ERF up front which needs a rigid cell to fit the scope...I used a ol' solar filter cell on one mod.

Then the adaptors for the PST etalon - usually bought...

The spacers between the etalon and the BF can be T thread spacers....

Which donor scope are you considering??

[Merlin]

I made an ERF cell from a metal can for a Stage 1 mod Ken, that was easy to do! The snag is that I can't download your Stage 2 instructions ( remember when we tried a while ago? ), so I'll just have to play it by ear.

The Stage 1 mod donor 'scope is a 70mm/f.10 achromat.

[Peter Drew]

Depends on how good you are at metal work. As I was a bit concerned about holding the rear end of a PST in my lathe I managed to open out the rear face of the black box by drilling out the periphery of a pre-marked off circle and then carefully filed it out to a good 1.25" fit for a RA diagonal as replacement for the pentaprism.

[Merlin]

Thanks for that info'. Yes, the blackbox would be way out of balance in a chuck.