Bahtinov focus mask 100 for 109mm to 145mm diameters, ASToptics

Product description:

Bahtinov focus mask

The focus mask is used to facilitate accurate focusing when doing astrophotography.

How to attach the mask to the telescope: Each mask is supplied with a pair of bolts and fitting plastic covers. Just push the bolts through the holes in the mask and slide the covers onto the bolts from the other side. Now the mask can be simply hinged onto the dewcap or the telescope tube. This adaptation is very universal and fits for widely varying tube diameters.

Specifications:

General

Colour black

Diameter (mm) 109 - 145