Kendrick Astro Bahtinov Focusing mask for 90 to 105 mm optic

Kendrick Astro Bahtinov Focusing mask for 90 to 105 mm optic

How to Use a Bahtinov Mask
First of all, the masks come with three adjustable rubber bumpers. This allows them to fit to a wide variety of tube diameters. Simply push the bumper to the desired location on the slot to ensure that the mask is properly centered over your optic. Then focus. The graphic below describes visually what you will see on either side of being focused. This graphic represents movement of the focuser in very small amounts (fractions of a mm). It is extremely sensitive.

NOTE: There are three ways to use the bumpers on our masks to achieve a proper fit to your telescope:

• Bumpers can be adjusted to fit “outside” of the tube or dewcap.
• Bumpers can be adjusted to fit “inside” the tube or dewcap.
• If fit cannot be achieved using the two methods above, flip the mask over to use the smaller bumper footprint on the flip side.

The Bahtinov Mask is probably the easiest product on the market to achieve tight focus for visual use and for digital astrophotographers, regardless of whether you use a DSLR or CCD camera.