Bahtinov focus mask for Meade 12" SCT LX 850, FP417 Bahtinov focus mask. fits Meade 12" SCT LX 850 Bahtinov Focus Masks make focusing for astrophotography easy; instructions included Works with all DSLR cameras or CCD imagers Simply place the Bahtinov Focus Mask over the end of your telescope Made in the USA by Farpoint Astro