Will the Deluxe Tele-Extender #93643 work with any eyepiece or Barlow? What about the HD Edge series

The Deluxe Tele-Extender has two setscrews that are designed to lock the main body of the extension tube to the visual back or onto a projecting eyepiece or lens. One setscrew must be removed from a visual back for the extender to go over the visual back.

Since the tube of the Tele-Extender goes over the eyepiece, the eyepiece or Barlow outside diameter must be smaller than the 45 mm inside diameter of the extender. Many eyepieces are too big to fit inside and can’t be used with the extender.

Celestron’s Omni series will fit the Tele-Extender. The older X-Cel series will also fit. The Celestron #93326 Omni and #93506 Ultima Barlows will also fit if the Barlow's setscrews are removed or replaced with smaller setscrews.

 

The Deluxe Tele-Extender has two setscrews that are designed to lock the main body of the extension tube to the visual back or onto a projecting eyepiece or lens. One setscrew must be removed from a visual back for the extender to go over the visual back. The EdgeHD visual backs are longer than the standard #93653-A visual backs. This is to take advantage of the EdgeHD’s optimum image size which is farther back than the same position for a standard Schmidt-Cassegrain telescope. The additional length of the EdgeHD visual back is a tapered, faceted cone surface that won’t allow the Deluxe Tele-Extender’s setscrews to achieve a mechanical grip on the visual back. So the extender can’t be used in the conventional way attached to the visual back.

It can be used if the eyepiece is gripped with the Tele-Extender's setscrews and not the EdgeHD visual back. This configuration isn’t as solid as when the unit is fixed to the visual back itself, so it's best with a small imager. 

Note: The EdgeHD optimum image distance is of most importance for the outer parts of the FOV only. If you are imaging planets or small center of the field of view objects, it makes no difference whether or not you are at the optimum distance. So a regular visual back #93635-A can be used with the Tele-Extender secured to it.