The Celestron Tele Extender Deluxe is used for photographic work with eyepiece projection. If you want to photograph greatly enlarged sections of the moon's surface or planets, the basic focal length of the telescopes must be extended with eyepieces. The Tele Extender Deluxe can only be used on Schmidt-Cassegrain telescopes. The extender is attached directly to the 1 ¼" eyepiece holder. A camera T-ring is also required. The equivalent focal length achieved with eyepieces is calculated as follows:
Equivalent focal length =
Focal length of telescope x distance between eyepiece and camera body (mm)/ eyepiece focal length -1
Example:
Telescope focal length = 2000 mm
Distance = 100 mm
Eyepiece focal length = 10 mm
2000 x (100 / 10) - 1 = 18,000 mm equivalent focal length
