Re: [ATM] Looking for 16" Ritchey Chrétien information

["Bob May" <bobmay@nethere.com>]

I have an early Star Instruments RC in the 10" size and the instrument works
very nicely although the Ronchi testing of the instrument shows a bit of
stepping in the curvature of the secondary's shape which looks like it was
figured locally with small laps.  The overall shape of the focused wavefront
is well within the 1/4 wave wavefront error criteria for a telescope tho and
it is a nice instrument to pull out for viewing the sky.  I wish that the
mechanical parts of the mount (Star Instruments just made the optics and a
previous owner did all of the mounting and so forth of those optics) were up
to the level that the optics are.
The OTA is only part of a telescope and you can easily get frustrated with a
telescope if the mount (mine was not made by Star Instruments!) is
substandard as mine is.
The Parallax scope doesn't mention how accurate their surfaces are much less
the total error to be expected so I'd find out what it is before considering
that maker.
I'll also note that the RC design can allow a nice flat field (best suitable
for the CCD camera work as you can't bend a CCD) with the right design.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net


_______________________________________________
ATM mailing list http://www.atmlist.net/