180 Bahtinov Mask -------------------------- The role of the Bahtinov mask - When placed in the front of the telescope, the telescope focusing mask can easily achieve fast and precise focusing without guessing. These focusing aids are also called Bahtinov, and the groove pattern is cut by laser. The mask can achieve precise focusing with any type of telescope, which will produce a unique, intersecting 3-line pattern. Suitable telescope diameter range for Bahtinov mask - Fits telescope tubes with an outer diameter of 178-213mm (7.0" to 8.38") Suitable for use on all types of telescope - reflectors, rafractors, Dobsonians, Mak-Cas and SCTs. Bahtinov mask application - Astrophotography application, when fast and clear focusing is required. Help astrophotographers save time and avoid blurry images caused by slight defocusing of the exposure. Just focus on the celestial object you want to shoot or nearby bright stars and adjust the focus until the intersecting 3-line pattern is displayed, indicating that precise focus has been achieved. -------------------------- Package Include: Bahtinov Mask 3 X Brass boltCompatible with any type of telescope, especially suitable for astrophotography, to help you get more accurate images. Once mounted on the telescope, three unique adjustable cushion brass bolt provide a firm grip. The rubber sleeve on the surface of the brass bolt can effectively prevent scratches on the surface of the lens barrel, increase the fixed friction, and improve the stability of the installation. Once accurate focus is achieved, the mask produces a distinct, intersecting 3-line pattern.Its material composition is strengthened plexiglass, which is shaped by precision laser cutting, which is strong and durable. The plexiglass material is not easy to become brittle. Mask fits telescope tubes with an outer diameter of 178-213mm (7.0" to 8.38") Suitable for use on all types of telescope - reflectors, rafractors, Dobsonians, Mak-Cas and SCTs. Focusing mask will help you achieve precise focus in a few seconds. Provide the best focus for your telescope quickly and easily without guessing.Compatible Devices: Reflector telescopes,refractor telescopes,Astronomical Telescope. Item Weight: 3 Ounces. Finderscope: Reflex. Focus Type: Manual Focus. Brand: Starboosa. Manufacturer: starboosa. Date First Available: November 11, 2021. Best Sellers Rank: #2,767 in Camera & Photo Products. Customer Reviews: 3.5 out of 5 stars 2 ratings 3.5 out of 5 stars. Item model number: SB1127. : B09LLRRH3Y. Item Weight: 3 ounces. Package Dimensions: 8.7 x 8.7 x 1 inches.