Maybe it is the first time you see a mask like this one. It is the first time for me at least. If you have a big Schmidt-Cassegrain telescope and had problems trying to collimate it due to atmospheric turbulence, you should try this mask.

Samir Kharusi employs it to reduce the effective aperture of the optical tube and soften turbulence. More details in his webpage; below you'll find the link.

by Samir Kharusi on 2009-05-23 15:04:03 [Original Size] - [Next Image] - [Author's gallery]