OO> > Anyway, this prompted me to wonder how others do the Foucault OO> test. Do > you set the knife edge in the beam and then move it OO> closer or further Michael,
Someone mentioned that a separate mask was used on a particular telescope featured in S&T (Christine I believe). I do something similar, but economize a bit. I use tape to form a hinge on paper flaps that cover zones not being tested. I found that this really did help me in being more objective in reading the shadows...especially on long focal length mirrors, but the same thing would benefit on the shorter lengths.
Mike
* RM 1.3 * Two can live as cheaply as one, for half as long.