TS-Optics 25mm M90x1 Extension Tube for 6" and 8" RC Focusers
TS-Optics M90 Extension Tube for the M90x1 thread - length 25 mm
Distance tube with 25 mm length for telescopes with M90x1 connection thread, for example for RC telescopes from TS-Optics, Astro Tech, GSO, ...
- Thread at telescope side: M90x1 thread (female)
- Thread at focuser side: M90x1 thread (male)
- The adapter is threaded between the telescope´s back wall, thus increasing the distance from the focuser to the tube.
Many telescopes, for example Ritchey-Chrétien telescopes, have much backfocus. This generous distance of the focus allows using a focal reducer or accessories like off-axis guiders. But if you want to attach only a camera or possibly just to do direct-vision observations, than the focuser has to be completely extended and additional 2" extension tubes have to be used. That reduces stability.
This M90 extension solves the problem. It is threaded between focuser and telescope and increases the distance betweeen telescope and focuser - see image at left.
The focal plane or focal point moves closer to the focuser and you don´t need to extend the drawtube that much. For attaining precise matching, you can also thread several M90 extension tubes together. A further advantage is the better illumination. The clear aperture of the extension tube is clearly larger than the clear aperture of a 2" extension tube.
|Thread at telescope side:||M90x1 thread (female)|
|Thread at focuser side:||M90x1 thread (male)|
|Optical path:||25 mm (without male thread)|
|Material:||Aluminium black anodized|