Celestron Tele-Extender Deluxe

Celestron Tele-Extender Deluxe
The Celestron Deluxe Tele-Extender for Schmidt Cassegrain telescopes is a hollow tube with which you screw your camera onto your telescope, with an eyepiece installed. By using the Deluxe Tele-Extender in combination with an eyepiece, you can increase the effective focal length of the telescope to well over 10.000mm! This technique is known as eyepiece projection photography.

Effective focal length
The following formula may be used to approximately determine the effective focal length: EFL = telescope focal length / eyepiece focal length x DF (the distance from the centre of the eyepiece to the film).

Use
The Celestron Deluxe Tele-Extender is used for lunar, solar and planetary photography and also for terrestrial photography. It fits over the eyepiece of the telescope (even big eyepieces) and connects to the visual back of the telescope. Optional counterweights will be necessary to ensure the right balance of the telescope when using the Tele-extender.

Place the Tele-Extender over the eyepiece, then connect the 35mm SLR camera to the back of the Tele-extender, using a T-ring.

Other information about the use of the Tele-Extender
The Tele-Extender features a built-in safety device which helps prevent the eyepiece from accidentally coming off. There are a few things to bear in mind when using this accessory. Firstly, the image you see through the finder will be reversed. Secondly, this accessory will realise an extremely high magnification. This means that you will have to make sure trembling of the camera and the telescope is kept to minimum. In addition, it is important to carry out accurate polar alignment.