This innovative focus mask concept was invented by a Russian amatuer astronomer, Paul Bahtinov, and Kendrick is producing these masks with his permission. The Bahtinov mask allows digital astrophotographers and visual observers to get razor sharp focus in seconds!
The method is very fast and incredibly sensitive. There is no guessing when you are focused during times of poor to moderate seeing. Simply put the mask and the status of your focus will become immediately apparent.
The masks have a series of slots that create a unique diffraction pattern that can be used to quickly bring your telescope to focus with an absolute minimum of fuss.
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. The plastic masks will require the user to devise a method of attachment. We suggest masking tape.
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.
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.