Flock It!

Photo of Protostar peel-and-stick flocking paperIf you have a Dobsonian or Newtonian reflector, flocking is a great way to reduce stray light and improve the contrast. What is flocking? It simply means lining or painting the inside of your telescope with something that absorbs light—ideally something that absorbs close to 100% of visible light. Most telescope insides are painted flat black, but that usually doesn’t do a particularly good job of absorbing incident light. If you don’t believe me, look down the inside of your telescope tube in the daylight: is it truly pitch black or just dark gray?

Flocking is particularly helpful in light-polluted environments because there is so much more stray light to eliminate. Think of it this way: if you are in a really, really dark site, flocking doesn’t matter much because there is essentially no stray light. In fact, in really dark skies, you don’t even need a light shroud around a truss-tube telescope—there is just no light to leak into your light path. In contrast, your typical urban or sub-urban environment has plenty of stray light sources: the neighbor’s porch light or bedroom light, the nearby street light, the sky-glow from downtown, and even the light-gray background of the sky itself. If any of this light gets into your eyepiece, it contributes to brightening the background and killing the contrast.

Now flocking is pretty easy and one of the secrets is that you only need to flock relatively small portions of your telescope to get essentially all of the benefits...


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