Focuser extension tube M117x1 25mm for Richey Crétien Telescope
Place the 25mm RC focuser extension ring between focuser and telescope rear mounting plate to increase the distance of your focuser from the optical tube rear plate.
This forms a very rigid connection and allows you to rack your focuser inwards as much as possible, reducing flex and strain on the focuser, and improving imaging performance.
Fits 10" or larger Richey Crétien Telescopes
Extension rings can be stacked on top of each other to get different extension distances, for example:
2x 25mm rings = 50mm total
1x 25mm ring and 1x 50mm ring = 75mm total
Generally speaking, 2x 25mm and 1x 50mm rings are used to get focus with a CCD camera and filter wheel for a total of 75mm extension. With an OAG, DSLR and filter wheel, sometimes only 50mm total extension is required.
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