A better anti-reflective coating (velour, (velour, velour), blackboard varnish, Berger anti-reflective paint) increases the contrast and sharpness.

The manufacturer's internal blackening on most telescopes is already sufficiently applied to protect against stray light. However, a better anti-reflective coating (velour, blackboard paint, Berger anti-reflective paint) will increase contrast and sharpness.

The effort is relatively minimal with a Newtonian:

Remove the secondary mirror spider using the four screws.

Remove the primary mirror and mirror cell.

Clean the tube and the drawtube of any dust.

Then either line the tube with velour or coat it with Berger anti-reflective paint or blackboard paint.

Reinstall and adjust everything.

We always recommend anti-reflective paint. Berger's water-based silicone resin paint is specially formulated to create a rough surface and thus provide slightly better protection against stray light in the tube.

With velour, abrasion from the velour often remains on the mirror. The velour isn't that difficult to clean, so some of the velour won't still release "material."

And blackboard paint is less effective than anti-reflective paint.

We usually apply the anti-reflective paint in three coats, which we then dry with a hot air dryer after each coat. We use paint rollers from the hardware store for this. We also blacken the secondary mirror struts and edges with a paintbrush. And anything else that might shine.

In the image, the Berger anti-reflective paint has been applied on the left, and the manufacturer's interior blackening is on the right.

http://www.astrogeraete.de/Antireflexfarbe.html

http://www.teleskop-spezialisten.de/shop/Optimierung-von-Tubus-und-Equipment:_:30.html