Quote:I got a Discovery split tube PDHQ 12.5" several years ago. I don't remember gluing the primary mirror to the cell when I put it together. It has retainer clips. I don't use it that often and always transport it vertically. How important is it that the mirror is glued to the cell? If the mirror was glued, would it be safe to transport the tube on its side? A small picture of the cell is on discovery's web site. I don't know what brand it is.
George RoffeKingwood, TX
Celestron 8SE Dobstuff 13.1": Swayze refigured Coulter mirror, 6 pt mirror cell (2 pt edge support) and CF focuser board made by me StarBlast 4.5 ST80/PortaMount II Zhumell 20x80/Oberwerk 15x70 on a Seronik-style tripod boom mount Hubble Optics 18 inch F/4 mirror.
A 60mm department store refractor started it all....
-DannyMy warehouseMy Channel
Quote: You don't want the mirror glued to the cell, you want it floating.
Quote:Quote: You don't want the mirror glued to the cell, you want it floating. This is really an over generalization. As Carey explained very well, larger mirrors can suffer astigmatism when glued. On the other hand Portaball telescopes use a glued mirror on their 12" scopes, and I have never heard of anyone in many years experiencing primary mirror astigmatism caused from the mounting in one of these scopes. Carl Zambuto swears by the set-up. As mentioned, Rob Teeter also is using glued mirrors in some of his scopes. That being said, I generally feel more comfortable with floating mirrors in my scopes. To see if it is an issue in your scope, you need to star test it. It is very easy.
- Stephen - www.zytratech.com - Gallery on Flickr Twitter Working on my 17" CDK and its Equatorial Mounting: Build Log on CN