The Celestron Deluxe Tele-Extender for Schmidt-Cassegrain telescopes is a hollow tube that attaches to a telescope with an eyepiece installed, allowing photography of very small objects such as the moon and planets. By using the Deluxe Tele-Extender in combination with an eyepiece, you can increase your instrument's effective focal length to well over 10,000mm! And this corresponds with a matching increase in image size. This technique is known as eyepiece projection photography. The following formula can be used to determine approximate effective focal length:
Effective focal length = Telescope focal length/Eyepiece focal length x DF(the distance from the center of the eyepiece to the film)
The Deluxe Tele-Extender is used for high-power lunar, solar and planetary photography as well as for extreme terrestrial photography. It fits over a 1.25" eyepiece up to 41mm thick and connects to the visual back of the telescope. Optional counterweights will be necessary to properly balance the telescope when using the Tele-Extender. Please note that Celestron's visual back, #93653-A, is required in all cases.
To use the Deluxe Tele-Extender, remove the diagonal from your telescope and insert an eyepiece directly into the visual back. Place the Tele-Extender over both the eyepiece and the visual back, then attach your 35mm SLR camera to the back of the Tele-Extender using your camera system's specific T-mount. The Tele-Extender's built-in safety device will help prevent your eyepiece from becoming accidentally dislodged.
There are a few things to bear in mind when using a Tele-Extender. First, the image seen through your camera's viewfinder will be upside down. Second, due to the extremely high magnifying effect afforded by this accessory, extra care to prevent camera and telescope vibration, accurate polar alignment and use under good seeing conditions will all assist you in capturing high quality images.