RE: [ATM] 25" mirror possibilities

["Jerry Reddell" <jerry.p.reddell63@sbcglobal.net>]

-----Original Message-----
  I need to make a sturdy stand before I can set it up for testing.  I have
held a small led above the mirror at the end of a stick.  The ceiling is
about 9.5 ft above the mirror surface and with the led at that point, the
reflected image still appears somewhat larger in diameter than the mirror.
Consequently I assume that the focal length is greater than 9.5 ft.
According to what I've read, a Wright Schmidt design would have the
corrector plate near the focal plane of the primary.  The original
instrument had the corrector at about 12.5 ft from the primary.  So...that's
the basis for my guess of about f6 for the mirror.  At least I can be sure
that it is not really "fast" like f2.5.

Thanks,
Dennis


My response:

Whoa a second. If the projected image on the ceiling appears larger than the
mirror then that suggests to me that the focal point is less than the 9.5
feet and likely less than 5 feet...because the image is now expanding rather
than coming to a point which suggest it is beyond the focal point.  Maybe I
don't understand what you did....


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