Is a SNT an APO??

Check out this ad...


http://www.astromart.com/classifieds/details.asp?classified_id=385542

Seems pretty questionable to me.

Jon

I guess it's a SC so it has a "lens", and it's also well color corrected ... but the "Walks, sounds like, and looks like a duck" don't make it a REAL duck (otherwise all the Newt owners will be seeling their scopes as APOs and hiking up the price - smile).

My Questar has the word apochromat on it's tube. Raytracing of SCTs, Maks, Schmidt-Newts, Schmidt-Casss, Houghtons, etc., typcially have a residual color error similar to a fluorite doublet. Check out Rutten, etc., Telescope Optics, Willman-Bell. It is all rather academic, because the secondary obstruction causes quite a bit of contrast loss, as much or more than the chromatic abberation of an equivalent achromat.

If that's an APO, then I'm going to start calling my Fiat Spyder a Ferrari. What, they're both red and Italian!

-Jason

Well, if your definition of apochromatic is "all colors coming to focus at the same point", then I guess...
I might feel differently if I had paid $1000 per inch for a TMB

Tim Iafolla