Celestron's deluxe tele-extender is a high-power photographic accessory for Schmidt-Cassegrain telescopes. It's a hollow tube that allows you to attach a camera to your telescope with an eyepiece installed. By using the Deluxe Tele-Extender in combination with an eyepiece, you can increase your telescope's effective focal length to well over 10,000mm! And with this comes a corresponding increase in image size.
It's a technique known as eyepiece projection photography, and it multiplies magnification by the distance from eyepiece center to the film plane, according to the following formula:
Effective Focal Length = Telescope focal length ? Eyepiece focal length X DF (distance to film).
The deluxe tele-extender is used for high-power lunar, solar and planetary photography as well as for extreme terrestrial photography. To employ the 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 and attach your 35mm SLR camera to the back of the tele-extender, using a T-ring. That puts you in business for fine, highly magnified astrophotography!
Note: The image you'll see through your camera's viewfinder will be upside-down. And, because of the extremely high magnifying effect afforded by the deluxe tele-extended, you'll want to take extra care to prevent camera and telescope vibration. Accurate polar alignment and using only under good seeing conditions will also help you capture high-quality images.
The deluxe tele-extender is only for Schmidt-Cassegrain telescopes!