Many astrophotographers know the problem: after accurate focusing, in one or two corners the stars are not pinpoints. Often, the sharpness of the image is compromise to a level that the image has to be cropped. Some possible causes of this problem are: a tilted camera sensor (fraction of a millimetre are enough) a tilted focuser a tilted focal plane of the telescope (common in Newtonian telescopes) tilted optical accessories by imprecise clamping As solution, a tilter can re-establish the parallelism between elements and therefore the details on the corners of your photo will return sharp. The best way is to calibrate it is using test images: Identify the corner of your photo which has unsharp / aberrated stars. Loosen the 3 pull screws (the smaller one). Slightly turn the push screws in correspondence of for the corner of the photo that is unsharp. Take a second image. If the sharpness has deteriorated, turn the adjustment screw in the other direction until all 4 corners of your photos has the same sharpness. Tighten the pull screws. Specifications Telescope connection thread M68 x1 female Camera connection thread M68 x 1 male Optical thickness between 9.3 to 12mm Female M68x1 thread length 4 mm Male M68x1 thread length 4 mm Outer diameter 95 mm
