ATM commercial optics

[Matt Devine <mdevine@nuera.com>]

Hi guys, I'm in the process of building a six inch f/8 Dob.  I have run the
numbers in Berry's book many times and am confident that I am on the right
track with the hardware I plan to buy.  I do not plan to grind my own mirror
this time, that will be the next scope.  Does anyone have a good source for a
six inch mirror.  I had assumed that you could not go wrong using some of the
"larger" telescope manufacturing companies, but I'm not so sure now having read
some of the past mail.  Any happy customers or info would be appreciated.  Also
I plan on using a low profile focuser (JMI), and a 1.30" secondary.  According
to the math, the exact secondary size would need to be 1.21".  Can I reduce
this size, or would it be advantageous?  I plan to use this scope for visual
only.  The last question I have is on focal length.  If a commercial 6" mirror
(f/8) can vary +/- 3%, how do you know what the exact focal length is?  Are
they stamped with this info?  Thanks in advance.

Matt Devine
San Diego, Ca.