Bahtinov Mask

[ColHut]

How many of you fellows use them for visual use? I was wondering as I have sometimes difficulty getting good focus on the moon and wondered if I get proper focus on a small star it should be right despite the seeing for the moon?

cheers

[mithrandir]

Since for all practical purposes when it comes to focusing the Moon and stars are at infinity, using a star will be fine. The Moon and planets are too big and bright and the diffraction spikes are indistinct.

[Benno85]

Apologies on a stuuuuuupid question, but does that mean that one could use the mask and achieve focus on, say, Sirius, and then to M42 and commence imaging without the need for refocusing? :shrug:

[Geoff45]

In theory "yes". In practice, you may get mirror movement in a reflector as you go from one part of the sky to another. You'd be pretty safe doing it with a refractor.
Geoff

[Benno85]

Cheers Geoff, I'd be using a refractor so you've put my mind at ease :thumbsup: