What is flocking a telescope?

BBC Sky at Night Magazine's Scope Doctor Steve Richards solves your practical astronomy ailments.

BBC Sky at Night Magazine's Will Gater reveals what to look for when buying your first telescope.

What is flocking a telescope?

It is important to stop internal reflections within a telescope in order to avoid any loss of contrast, which is why telescopes have a matt black interior. However, the paint that’s used is rarely completely non-reflective or pure black.

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Lining the inside of the telescope tube with black flocking material is a very effective way to kill unwanted reflections, as stray light is absorbed by the rough and very black surface.

If you remove the eyepiece and dust cover and look through the focus tube, every surface that you can see (with the exception of the mirrors) should be covered with flocking material.

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Email your astronomy queries to Steve at scopedoctor@skyatnightmagazine.com and they could get answered in a future issue of BBC Sky at Night Magazine.