From: georgea{at}cam.org
To: tkrajci{at}san.osd.mil
Cc: atm{at}shore.net
Reply-To: georgea{at}cam.org


Hi Tom

I'd have to agree with you 100% on having solid measureable data for
judging scopes at competitions.
I know of way too many instances where it was impossible to star test the optics.
At CAFTA they positioned a sign with lines similar to the Air Force
resolution target about 1/4mile away and optical performance was based on
which was able to resolve the greatest number of lines. Not the ideal test
but since the clouds were there for two days...
Leaving optics performance, mount stability, damping, etc up to subjective
assesment is looking for biases to work their way in. Much of the
"test equipment" is inexepnsive or even simple to make. It would
just require a bit mor in the planning stage of the event (not that
organizers have a lot of spare time).
What would be interesting is the data logger for your cooling test, 200
thermocouples or semiconductor probes all connected to a datalogger and the
thermal graphs superimposed on a topo map.

George Anderson
Montreal Canada

Clear skies (someday next month I hope)


Quoting Tom Krajci :

> >From: georgea{at}cam.org [mailto:georgea{at}cam.org]
>
> >As a person who has actually used this scope for viewing on several
> >occasions
> >including public star parties I can say the following.
>
> Now that I try and wade through the vitriol of my initial post...my
> greatest concern is with the organizers of Stellafane, not the
> individual ATM's.
>
> I repeat that I think Stellafane, and all other big star parties, should
> seriously consider establishing testing criteria for telescope
> mechanical and optical performance that can be performed on cloudy
> nights or in daytime.  Accelerometers and artificial stars are not
> expensive or difficult for large clubs/organizations to acquire.  They
> provide an opportunity to standardize the testing process, and make it
> repeatable from telescope to telescope...and from night to night.  The
> subjective aspect of performance evaluation will be minimized to the
> maximum extent possible.
>
> This will help increase understanding in the ATM community of what
> design and fabrication features provide the best performance.
>
> There will always be competitions and judging with some, or a great deal
> of subjective evaluation...such as 'greatest innovation in design',
> etc....but think of a top fuel dragster on the quarter mile track...no
> subjective analysis required...just naked performance.
>
> And another thought came to me.  Stellafane and others could test the
> cooling performance of scopes.  Attach a temperature probe to the back
> of the main mirror in the evening, and also monitor the ambient air
> temperature.  The call of "Gentlemen...start your cooling fans" will
> echo across the observing field. ;-)  Measure how fast the mirror temp.
> approaches ambient temp.  Again, this helps take subjective judging out
> of the loop, and shows interested ATM's what works, and what does not.
>
> Tom Krajci
> Tashkent, Uzbekistan
>
>
> ---

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