Bahtinov mask

The Bahtinov mask ( after its inventor Pavel Bahtinov ) is a focusing aid for amateur telescopes, similar to the Scheiner aperture. The Bahtinov mask is required for astrophotography because it is' arrives here on the highest accuracy in adjusting the focus. The Bahtinov mask is placed in front of the foremost optical element and produces a beam -shaped pattern in the field of vision. The more closely the ideal focus point is set, the more central is to see the longest of the rays. In complete symmetry of the image of the point of focus is reached. Due to the high number of slot-shaped openings reaches a relatively large amount of light to the observer; Scheiner the aperture, however, is more suitable due to their low light intensity to bright stars.

Disadvantage in self-made, however, the production cost since the corresponding number of slots must be cut from a sufficiently rigid material. Moreover, the number, position and size of the slots on the focal length and the aperture of the instrument is dependent, so that a new Bahtinov mask must be made ​​for each additional telescopes.

Picture of the Bahtinov mask in the camera viewfinder or eyepiece