Yes you are correct and I am glad you raised this.
I should have covered that aspect but simply forgot in my rush to put up the thread.
Mine could be a little better in the unit I am using but I did round things up.
I plan making a much better one that will incorporate a light box..it's on the to-do list..I bought the lights many months ago...I started one for the eight inch that was not perfect and I destroyed it...one of my perfection is only just good enough moments...
What I have been considering is another system which involves having the rings printed at a print shop but I have yet to price that approach.
What would be nice is aluminium disks with nice sharp edges and maybe down the track that could come to pass . . Maybe carbon fibre but I have not worked with carbon fibre as yet.. should not be too hard but again so much I have to do...I have the observatory to finish which is nearly there but two piers to construct as well..
Nevertheless I really believe the minimisation of stray light is just so important that in time I will probably get more professional with these dew tubes...
So you are a sand man and I favour saw dust (less weight
) do you have a reason to use sand over saw dust is my question.
Further I am so glad to have an endorsement from someone as capable as your self.
I promote the idea so often and end up feeling no one thinks much of the idea...Having Hubble do it is good but having you do it is even better.
I would have thought that someone would be making them and selling them really.
Thanks for your input I greatly appreciate you doing so
Alex