Variable Tele-Extender for all SCTs

The Variable Projection Tele-Extender allows you to do high magnification eyepiece projection photography with your camera body, a compatible t-ring, a reasonably sized 1.25" eyepiece, and your Schmidt-Cassegrain or Maksutov-Cassegrain telescope.  The telescope side of the Tele-Extender threads onto a standard 1.25 " eyepiece holder, aka visual back, which normally comes with your SCT to allow attachment of a diagonal.  The other side of the variable tele-extender threads onto a standard M42 camera t-ring that is fitted to your SLR or DSLR camera.  

The "eyepiece projection" takes place when you slide a 1.25" eyepiece inside the barrel of the MTele-Extender.  You can see now why I said "reasonably sized" earlier on, since the barrel will not accept eyepieces of larger diameters.  Many amateur astronomers use a 1.25" Orthoscopic eyepiece, or a Plossl for this purpose, since the design is fairly svelte.  You may find that the rubber eyecup must be removed, or even the rubber grip.  

The beauty of a Variable Projection Tele-Extender is its ability to adjust in length.  This will change the magnification you end up with for a given eyepiece, since lenghtening or shortening the tele-extender changes the focal length.  

You can also use this Tele-Extender for prime focus photography.  Just adjust the length accordingly and then photograph through the tele-extender without an eyepiece installed.