Starboosa Telescope T2-Extension Tube Kit for SLR Cameras and Eyepieces - Length 3mm 5mm 7mm 15mm 20mm 30mm 55mm - M42x0.75 on Both Sides (Upgraded)

Extension tube kit is used to obtain the correct image focal length or exact spacing required, thereby solving the spacing problem in astrophotography. This set adds 55mm to the original 3mm 5mm 7mm 15mm 20mm 30mm. An upgraded package of 7 Extension Tubes.(Tips: The inner side of the added 55mm has no thread for eliminating reflection. The connection port thread at both ends is M42x0.75.). The required spacing can be achieved by combining several extenders of differing lengths;you can use 1 piece;2 pieces;3 pieces ;4 pieces;5 pieces;6 pieces; 7 pieces of the extension rings as you like.. The M42x0.75 threads on both ends make it versatile. External thread M42 * 0.75; internal thread M42 * 0.75; a series of focusing problems are eliminated.. By combining multiple extenders of different lengths, you get the right focal length to focus with the camera or eyepiece.. All metal construction and anodizing aluminium process;durable for long time use.