From: "Mike and Sara" 
To: 
Reply-To: "Mike and Sara" 


Hello!

    I plan on trepanning the secondary to 2 1/2 inches, as I did the
spherical secondary I made.  Using classical 1:6, the thickness should be
just under 1/2 inch, which is what I made the spherical secondary for my
proposed D-K system.  Would 1/4 inch be too thin if I try and convert to a
classical cassegrain?

The I see it, the advantage to using the lens would be that there should be
no zones and minimal edge problem if I get a high quality lens such as from
Melles Griot, and with the BK7 higquality glass, I should be able to using
through the back testing to get a rough figure, then star test the final
system.  I don't know what the foucault numbers would be; if anyone has
such expertise, it would help me see if I should attempt it.  Regardless,
it may be more than I can do in any case, and I would hate to figure the
primary as paraboloid, only then to have to return to ellipsoid and use my
spherical secondary if I fail in making a classical cassegrain hyperboloid
secondary with the BK7 lens.  Best regards.

Mike

--- BBBS/NT v4.01 Flag-5