Most popular solar scope mods

[wkyee]

I think there should be a sticky here for us beginners: The most common mods for the most popular scopes. Beginning with, what is

Stage I

Stage II

[peter drew]

Assuming the consideration is for a PST mod then Stage 1 refers to using the complete original black box assembly in conjunction with a donor telescope. In a Stage 2 mod either the complete black box or its internals are removed and the components are reconfigured in the same sequence but discarding the pentaprism which is often the source of optical issues.
To retain the full aperture of the donor telescope objective, the focal ratio should not be less than F10. Almost any good quality achromat of this focal length will be ideal. The common cost effective aperture seems to be 100mm, the Tal 100RS being a popular choice.