In 2008, Pavel Bahtinov, a Russian amateur telescope maker and astronomer, published an ingenious new way to easily focus your DSLR camera, webcam or CCD camera for astrophotography. The method is simple, very intuitive, and the device has universally been named after the inventor: The Bahtinov Mask.
Farpoint manufactures this great astrophotography tool out of virtually indestructible ABS plastic, which comes in two major types and in a range of sizes. We carry masks designed to fit DSLRs, refractors, Newtonian telescopes, as well as SCTs.
Focusing with your Bahtinov mask is simple. Start by snapping the Bahtinov mask into an inexpensive UV or Skylight filter that fits your camera lens. [FILTER NOT INCLUDED, MUST BE PURCHASED SEPARATELY] Center a fairly bright start in your camera and achieve a rough focus, then loosely screw the filter holding the mask onto your camera lens.
Take a short exposure. The image of the star will show diffraction spikes. The “center” set will most likely be shifted to one side or the other. This is showing the defocus.
Adjust the focus of your camera and re-expose the star, once again showing the diffraction spike pattern. Iterate the process until you get the central diffraction spike centered against the star and the other spikes. When you achieve a symmetrical pattern, you have achieved the best possible focus. Remove the mask, center your target object and take your images!
Farpoint manufactures this "lifesaving" astrophotography tool out of virtually indestructible ABS plastic in a range of sizes for DSLR camera lenses. We currently offer 52mm, 58mm, 62mm, 67mm, 72mm, 77mm, and 82mm. These masks are designed to snap onto a UV filter. The Farpoint snap-in Bahtinov Masks do NOT include a filter. Typically, photographers keep a UV filter on their lens permanently just to protect the lens. Since camera lens filters are stackable, Farpoint recommends that you keep a UV filter permanently on your lens and then LOOSELY thread a second UV filter with the snap-in Bahtinov onto your protective UV filter. That way, your lens will always be protected and you will be able to easily remove the Bahtinov to take your photos.