Re: Star Testing using large disc

On Nov 6, 10:32 am, canopus56 <canopu...@xxxxxxxxx> wrote:
On Nov 5, 6:28 pm, Tenifer <tensorsur...@xxxxxxxxx> wrote:

I wasn't able to test it at an airy disc
because the sky was not clear enough . . .

As noted in Suiter's book, a silver sphere Christmas ornament and a
small flashlight can be used to create a point source under cloudy
skies or at night. During normal daylight testing, the glint of the
Sun off the sphere or a ceramic telephone pole insulator is used to
create an artificial star. I use a ball bearings because they are
smaller and make smaller glints (either from a flashlight or the
Sun). Thus, they can be placed closer to the telescope than a larger
Christmas tree ornament and the glint still has the angular size of an
Airy disk. See Suiter's book for details. My artificial stars look
like this -

http://gallery.utahastronomy.com/v/kurt/atm/007.jpg.html

http://gallery.utahastronomy.com/v/kurt/atm/008.jpg.html

Cloudy skies, either at day or night, is not a constraint preventing
the creation of a point source artificial star.

- Canopus56

Do you know where I can get a tested Celestron C9.25" with
at least 1/8 wave optics? I read that you can push a Celestron
C9.25" to 450X with a 1/8 wave optics while you can only reach
250X with a 1/4 wave optics and only 150X with a 1/2 wave
optics so with the central obstruction, one needs to focus on
getting a good one to make use of the full resolution. Know
any dealer who sells tested one for additional fees? Just
email me in private if you know of one so I'd be the first
ones to reach the best of his stocks. Thanks.

Teni

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