Expert: Tom Whiting - 9/18/2010

Question
QUESTION: I want to make some light baffles to go inside my 12" metal-tube Dob. What would you recommend? Plywood? Cardboard would be susceptible to dew I think. I believe that in the USA people sometimes use Kydex, but that is not avalable AFAIK in New Zealand.
Thank you.

ANSWER: Hi Paul,
I don't think Kydex is suitable for that; you want light-weight black
flocking material.  I've never light baffled a tube with black flocking, but we have a club member that has with his 12 inch Meade scope, and is very religious about it, not allowing even one photon to escape his attention... so I asked him what he used, and here is his answer to me (cut and pasted)...


http://www.fpi-protostar.com/flock.htm

Protostar has the best black flocking paper, with an adhesive backing.  I also had to staple it in order to keep it on the tube, but that was the old stuff.  THey have detailed directions on keeping it in the tube, and as you know, it works very well.  Similar to velour, traps all stray light and does not reflect.  

So there is his best answer to you... I've viewed through his scope and for some objects, it nearly equals my open truss 18 inch, with his much higher contrast!!
Hope this helps,
Clear Skies,
Tom Whiting
Erie, PA USA



---------- FOLLOW-UP ----------

QUESTION: Thank you, that is an interesting site, but I meant the circular ring-shaped baffles like those many refractors use to block the light path at the very edge.

Answer
Sorry Paul, I can't help you there... I just assumed they were made out of thin plywood circles, and just spray painted flat black.  But as a further help, one of our astronomers on allexperts, Paul Wagner, has built many telescopes, including refractors, so he might be able to help you with this question far better than I can.  So please write your question to him.
Clear Skies,
Tom Whiting
Erie, PA USA