The Bahtinov or focusing mask is a brilliant aid to get a perfect focus. When the telescope is pointed toward a bright star, the mask generates a specific diffraction pattern that makes the focusing procedure easy. Adjust the focus of your telescope till you will see a symmetrical pattern.

The mask is laser cut from glossy black acrylic and has slots for the included bolts which makes it possible to clamp it onto either the outside or inside of your telescope tube.

Specifications

65mm - 100mm mask inner tube clamping range	77 mm - 108 mm
65mm - 100mm mask outer tube clamping range	62 mm - 96 mm
85mm - 120mm mask inner tube clamping range	97 mm - 131 mm
85mm - 120mm mask inner tube clamping range	81 mm - 115 mm
105mm - 150mm mask inner tube clamping range	120 mm - 167 mm
105mm - 150mm mask inner tube clamping range	105 mm - 152 mm
125mm - 180mm mask inner tube clamping range	145 - 192 mm
125mm - 180mm mask outer tube clamping range	130 - 179 mm
150mm - 200mm mask inner tube clamping range	166 mm - 213 mm
150mm - 200mm mask outer tube clamping range	151 mm - 198 mm
175mm - 220mm mask inner tube clamping range	186 mm - 232 mm
175mm - 220mm mask outer tube clamping range	170 mm - 218 mm
195mm - 240mm mask inner tube clamping range	204 - 255 mm
195mm - 240mm mask outer tube clamping range	192 - 239 mm
215mm - 260mm mask inner tube clamping range	229 - 276 mm
215mm - 260mm mask outer tube clamping range	212 - 261 mm
250mm - 290mm mask inner tube clamping range	264 - 310 mm
250mm - 290mm mask outer tube clamping range	247 - 295 mm
290mm - 340mm mask inner tube clamping range	306 - 354 mm
290mm - 340mm mask outer tube clamping range	292 - 340 mm

FOCUSING MASKS