Description
The Bahtinov Focus Mask is a tool designed for use with a Meade 10 FP413 telescope. It is used to achieve the best possible focus when taking images with a camera attached to the telescope. The process involves centering a bright star in the telescope, placing the mask over the front aperture, and adjusting the focus until the diffraction spike pattern is symmetrical. Once this is achieved, the mask can be removed and images can be taken.
Attach your camera to the telescope, center a fairly bright star in your telescope and achieve a rough focus. Then place the mask over the front aperture of your telescope. 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 telescope 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!