Quick easy focus for your astrophotos! Farpoint Bahtinov Masks are an ingenious new way to easily focus a telescope. Pavel Bahtinov, a Russian amateur telescope maker and astronomer, created this simple, very intuitive method and the device has universally been named after him: The Bahtinov Mask.
To know what size to choose, measure the diameter of the outside of your dew shield (or OTA) and select your Focus Mask size accordingly. For more information: https://youtu.be/65TLAzl75lw