can I convert a newtonian telescope to a schmitt-casegrain ?

Question

I have a 10" newtonian mirror in a semi-working home made telescope. Can I send the primary mirror to a lab and have them cut a hole in it to make a schmidt casegrain ? I know I need a special secondary concave mirror, but can they drill a hole in the primary mirror once its coated or do I have to pay for a new coating ?

Answer 1

I think you run a considerable risk of scratching the mirror when the hole is bored. Cassegrain mirrors are usually bored before grinding and polishing. Also, as stork5100 points out, the figure of a Newtonian mirror is wrong for a Schmidt-Cassegrain.

But the bigger difference is that Cassegrain systems are generally based on a short focal ratio primary. You could build a classical Cassegrain based on your Newtonian mirror, but it would probably be f/30 or longer. The primary in a typical SCT is around f/2.

You're also going to have to figure a way to make that corrector plate if you want a Schmidt-Cassegrain. (And the secondary is convex, not concave.)

Answer 2

Sorry, but that won't work. Newtonian reflectors have a primary mirror with a parabolic curvature. Schmidt-Cassegrain's primary have a hyperbolic curvature. Even if you have a hole drilled into it, lights rays on your Newtonian will not converge correctly in a Schmidt-Cassegrain configuration.

If you want to convert, you'll need a new set of mirrors. But, you'll be able to reuse the tube, mount, eye-pieces and and sighting scopes.

Answer 3

That relies upon on what you're drawn to doing maximum. For seen gazing of galaxies, nebulae and the planets too, a 10-inch or greater Newtonian or Dobsonian is tricky to conquer. in case you intend to do astrophotography, an 8-inch or better Schmidt-Cassegrain, a 4-inch or better apochromatic refractor or a 6-inch or better Maksutov-Newtonian are difficult to conquer while paired with the amazing equatorial mount. different factors you are able to desire to evaluate are the place you reside, what style of motor vehicle you have and your wellbeing. a sturdy place to start up answering those questions is a neighborhood astronomy club, or attending nationwide or close by megastar events. There you are able to attempt all forms of telescopes in guy or woman, and get an thought of what you want.