Astro-Tech 80mm extension tube for Ritchey-Chrétien  imaging

This Astro-Tech 80mm long x 2" diameter extension tube can make up for the loss of light path when a 2" star diagonal is removed from many refractor telescope focusers and replaced by a camera and camera adapter for imaging.

This Astro-Tech extension tube is also used with Astro-Tech Ritchey-Chrétien reflectors. With these Astro-Tech scopes, the scope’s focuser is used by itself or (more typically) in combination with one or both 2" thread-in extension tubes supplied with the scope to place the camera or eyepiece at the fixed telescope focal plane. A single extension tube will often do the trick for visual observing with a star diagonal. Both extension tubes will generally be needed for imaging with webcams and DSLRs.

In some cases, however, there still may not be enough focuser extension for webcam use when using both extension tubes with an Astro-Tech R-C. This 2" compression ring extension tube can be slipped into the 2" accessory holder of the Astro-Tech R-C’s focuser to add 80mm of extra focuser length. Optional Astro-Tech 35mm and 50mm extension tubes are also available. A little experimentation will be called for to determine what combination of focuser and extension tube(s) will be needed for your particular combination(s) of visual and/or photographic components.

One end of this Astro-Tech 2" diameter x 80mm long extension tube fits into 2" focuser drawtubes. This end is threaded to accept 48mm filters. A shallow safety groove is machined into the barrel of the extension tube. This groove engages the thumbscrew or compression ring of your focuser to prevent the extension tube and your camera from falling should the focuser thumbscrew loosen accidentally during use. The barrel extends 35mm into the focuser drawtube to provide a secure tilt-free installation when the focuser thumbscrew is firmly tightened.

The opposite end of the extension tube has a 2" diameter accessory holder that uses a non-marring brass clamp ring to hold 2" accessories in place. This accessory holder adds 80mm of extension to the light path when the extension tube is seated firmly into your focuser. The overall length of the extension tube is 115mm, 35mm extending into your focuser with 50mm of external light path extension. The extension tube is machined of aluminum, anodized black. The interior has anti-reflection threading. 

Just $29.95