Re: ATM Catch a Wave

["Frédéric Géa" <GEAF@CSI.COM>]

Hi,

Some friends of mine explain me how to have a good edge support and mirror
cell. I have put most of this information in a web page at :
http://www.astrosurf.org/jupiter/altaz/astatique.htm

For the edge support, you can go at :
http://www.astrosurf.org/jupiter/altaz/ameliorersupport.htm

The small wire is a piano wire (Frankly, I don't know if it's a english word
:))

I'm currently finishing (I hope I will use it within 2 months) this cell for
my 22 inc. I have seen this setup works perfectly for a 24 inc, 1,6 inc
thick primary. Seems to be harder to make but their is not lot more do than
for an ordinary dobson mirror cell. I only got a press drill to make small
conical and spherical shape. That's not a lathe but that help a lot.


Sorry all this pages are in french but that could be intresting for drawing
and pic.

Hope this help.

Frederic Gea
http://www.astrosurf.org/jupiter/altaz/index.htm#index


-----Message d'origine-----
De : Krajci Tom J Maj 27 OSS/IN <Tom.Krajci@cannon.af.mil>
À : 'atm@shore.net' <atm@shore.net>
Date : mercredi 2 août 2000 01:30
Objet : RE: ATM Catch a Wave


>
>
>> From: Aplanatic@aol.com
>
>> To ask for great performance when the mirror is pointed at the zenith
>> and then ignore the performance when pointed near the horizon is
>> not so intelligent.  It's really this aspect that needs addressing.
>
>> The real problem with mirror cells is performance when the scope
>> is pointed at some large angle with respect to the zenith.  This can
>> cause quite a bit astigmatism for thin mirrors.  In my opinion this
>> effect is typically much larger than 1/60th wave RMS for a
>> large Dob.
>
>I have RTV'd my mirrors to their cell support points.  Do you consider this
>a reasonably good method to avoid the 'horizon potato chip' syndrome?
>
>>...I humbly suggest that the criteria for a good mirror cell be
>>more like 1/60 waves RMS.
>
>One of these years I hope to start work on a larger scope...in the 24-32
>inch class.  Hmmmm, I may give that some consideration...make a mirror cell
>with fewer supports that gives about 1/60 wave RMS deformation.  If this
>noticeably degrades the image...then all I have to do is re-work the mirror
>cell with more points.
>
>Tom Krajci
>