The Bahtinova mask is an unparalleled help in focusing in digital astrophotography; model for Celestron C11 telescopes. Focusing the image of a bright star (the clearer it is, the easier procedure is) we are sure to precisely "hit" the focal point. There is no need, as it often happens, to seek out the focus by trial and error.
• Active diameter: 280 mm
• greatly facilitates focusing for astrophotography
• is more sensitive to defocus than digital methods (FWHM, FocusMax, Robofocus etc.)
• Mask diameter: 340 mm
• mounting range (supported diameters): from 285 to 340 mm
• a universal system for attaching the mask on the tube
• made on a digital machine tool made of resistant plastic
>> FREQUENTLY ASKED QUESTIONS <<
Question : How does the Bahtinov mask work? When do I know that the image is sharp?
Answer : We choose the brightest possible star. We preset the focus. To set the focus precisely, let's see the appearance of the star near the sharpness setting.
• on the left: the center radius unevenly distant from the outside - we are away from the focus; radius
• measure: it is better but still not perfect
• on the right: the central ray is evenly distant from the external rays - the focus is set
Question : How do you attach the mask to the telescope?
Answer : It's best to make such a frame as for a solar filter, vide: http://teleskopy.pl/filtrsloneczny.html