This is the image of a moderately bright star (Markab, in the constellation Pegasus), photographed through the 8" reflector with a Bahtinov mask installed. The focus is very close but not quite perfect. A very slight adjustment will bring the horizontal line up slightly so that it intersects the other two lines exactly where they cross.

Unlike many other focusing aids, the Bahtinov mask works quite well with less than optimal sky conditions. I usually focus my telescope using the Bahtinov mask just after acquiring the flat field images, before the sky is fully dark. Poor astronomical seeing conditions, which cause blurry images and interfere with other focusing methods, have little or no effect on the Bahtinov mask process.