Farpoint Focus Mask C9.25 (Fastar) fits Fastar/Hyperstar READY C9.25 SCT’s. It does NOT fit with the Hyperstar or Fastar camera installed. But if you look carefully, you will see a slit that goes almost all the way across one side. Just complete that slit and you can flex (twist) the mask to open it up to get around the camera.
Farpoint Bahtinov Mask – Celestron 9.25 SCT (Hyperstar/Fastar) is 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.
Adjustable Bahtinov Focus Mask C9.25 (Fastar) for all newer Celestron 9.25″ SCTs (post 2008). Virtually all newer Celestron SCTs have the larger secondary holder for Fastar or they are “Fastar Ready”. The FP415H also works without HyperStar.
Attach a camera to the telescope, center a fairly bright star and achieve rough focus. Then place the mask over the front aperture of your telescope by “hanging” it on the plastic screws from the front dew shield. 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 the telescope and re-expose the star, once again showing the diffraction spike pattern. Iterate the process until the central diffraction spike is centered against the star and the other spikes. When a symmetrical pattern is achieved, the best possible focus is then reached. Simply remove the mask, center the target object and take amazing, sharp images!
Farpoint manufactures this “lifesaving” astrophotography tool out of virtually indestructible ABS plastic, which comes in two major types and in a range of sizes. In addition to Bahtinov masks for telescopes, Farpoint also makes Bahtinov masks for DSLR camera lenses.
Bahtinov Masks Are one of the best tools for manually focusing your telescope available to astrophotographers. In 2005, Pavel Bahtinov, a Russian amateur telescope maker and astronomer detailed a new way to easily focus your DSLR, CMOS or CCD camera for astrophotography by adding a mask that matches the diameter of your telescope.
Bahtinov mask are a less expensive method of getting focus on objects in the night sky compared to a standard motor focuser.
With the right mask and setup it’s easy to get crystal clear focus on a star in less than 90 seconds.