Re: ATM secondary thickness

["Bill Prewitt" <bprewitt@neo.rr.com>]

With a truss-tube scope, you do not have much choice in placing the secondary
hole.
Unless you have a very long cage, you should place it where the baffling is
best, and adjust the length of the tubes for best focus. (IMHO)

By supporting the cage in front of the mirror box, and trying to focus each
eyepiece, you can find the correct length for your poles by direct measurement.

If you ever plan to get a 31mm Nagler, or add a drive and do imaging, you will
need about 2 cm more in-travel.
I adjusted mine so a 35mm camera can reach focus, and use a short extension tube
for normal eyepieces.
The extension tube actually improves the baffling of stray light.
          Bill Prewitt

My webpage of telescope making and caving
http://home.neo.rr.com/imaging
> >>
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> >> One of the last things I have to make for my 20" truss telescope is a
> >> focuser hole. Therefore I need to know the thickness of a 3.1 inch
> >> secondary. Can someone please tell me the thickness?
> >>
> >> Thanks,
> >>
> >> Jan
> >> http://www.geocities.com/janvangastel/
> >>
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