The Farpoint Camera Filter Bahtinov Focus Mask is an ingenious new way to easily focus your DSLR camera, webcam or CCD camera for astrophotography. 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.
This Bahtinov Focus Mask snaps-in to your camera lenses that have the specified size filter thread.
The Bahtinov focus technique works best with longer focal lengths and becomes less useful with shorter focal lengths. The practical useful limit is around 100mm focal length or longer.
(Don’t confuse focal length and camera lens size).
Farpoint manufactures this “lifesaving” astrophotography tool out of virtually indestructible ABS plastic. In addition to Bahtinov masks for DSLR, webcam or CCD camera lenses, Farpoint also makes Bahtinov masks for telescopes.