Originally Posted by binofied
I am putting a 450mm long dew shield onto my 10" Meade F10 OTA. It is actually running at F6.3 or 1600mm with a celestron focal reducer.
What size should the open end be?
The normal tubes from Meade are 300mm and parallel. However this is for F10.
Also i am going to make it like a baffled tube with rings about 20mm wide and 300mm ID then covering the outside with balsa sheet. There will be three rings bottom mid and end of tube. This way there will be less reflection from the sides as they will be in the shade of the rings.
So is 300mm wide enough at the open end? Or does it need to be a tapered tube?
I use a astrozap flexible dew shield on my LX200 10" and this also runs parrallel to the tube. I use my scope at F10, F6.3 and F3.3. The dewsheild does not interfear in any way so tapering is not necessary. Why would you bother to baffle the dew shield??? Mine does a great job of keeping stray light out and you really do not want to add any extra weight to the tube espeacially if there is little or no gain optically. The OTA is well baffled in anycase.