Re: ATM A few questions before I screw my Dob together for the firsttime..

[NGC704@aol.com]

In a message dated 6/21/99 10:03:53 PM Central Daylight Time, 
Richard.Rovelstad@worldnet.att.net writes:

> I have used a black marker to darken the edge of the diagonal mirror, should
>  I do the same for the primary?  Also, should I put a mark or a sticker in
>  the center of the primary to aid in collimation?  Lastly, I remember 
reading
>  about making a collimation tool from a 35mm film container, but I can't 
seem
>  to find the reference now that I need it.  Any replies appreciated.  Thanks
>  for reading.
>  
Hello, Peder!
        I'll defer on the question of darkening the diagonal mirror's edge in 
deference to more expert opinion than my own, and await with equal interest 
the replies. But the other two I'll take a swing at..
        I like to use a hole reinforcer as a center dot on the primary 
mirror, as it allows use of laser collimators if desired. Paint it black with 
your marker before installing it. To place it dead center, cut a mirror sized 
circle of paper with an Xacto knife or razor, using the mirror as a guide. 
Then fold the paper circle twice. Then cut the tip off the resulting "pie 
slice". Then unfold the paper and use it as a center-finding template on the 
mirror's face (easy - no pressure!). With a Q-Tip, apply a small dot of latex 
house paint to the exact center of the mirror, then use this as a guide to 
place the hole reinforcer. Finally, wipe off the latex with the other end of 
the Q-Tip (moistened - the paint hasn't had time to dry).
        For the film can collimating tool, get an ordinary plastic 35mm film 
can and cut the bottom off. Then drill a 1/16" diameter hole in the center of 
the film can's cap, using the molding dimple to find the center. Put the cap 
back on the can, and voila! you have a collimating tool. It will fit into a 1 
1/4" focuser perfectly.
        To gussy it up and make it more "professional", cut 1/16" to 1/8" 
strips of aluminum foil and glue 'em to the inside of the film can's cap, 
centered on the hole, to make "crosshairs". Then you'll have an official Al 
Kelly Collimating Tool!!
Regards,
Kurt Maurer
League City, Texas
http://members.aol.com/Funyfrm/index.html