[Mokusatsu (Australia)]

What sort of fabric is considered appropriate for a light shroud on a truss scope?

I have a Skywatcher dob, with the three rod extending tube design, which can be tricky because if the fabric is stretched around the circumference of the tube it will form a triangle and partly obstruct the light path.

If I attach it (via Velcro) to the circular tubes so the fabric is relatively taut when the tube is fully extended it will work, but when the fabric loses its elasticity it would again sag in the light path, so I suspect a stretchy elastic t-shirt type of fabric would not last very long.

So... I am thinking of black linen?

Does anyone have any suggestions?