Type of bahtinov mask for SCT / Mak

[bendiddley]

Does anyone know if its essential for an SCT or Mak to have a Bahtinov mask with the hole in the middle for the secondary mirror or can a standard Bahtinov mask be used?

[GuLinux]

The hole is never needed for optical reasons. It is only needed for mechanical reason, i.e. letting the secondary holder pass through the mask.

Since this is not a problem on a Mak, it's unnecessary to make one

[bendiddley]

Thanks

[johninderby]

A farpoint mask for a C11 SCT with the centre hole.