INSTRUMENTS

ASTRAL TELESCOPE

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ALIGNMENT OF THE FINDER

FOCUSING OF THE TELESCOPE AND ALIGNMENT OF THE FINDER
From the equipment supplied with the instrument choose the ocular with the longest focal length (on every ocular there is a number indicating the focal), and insert it into the ocular holder (fig. 1), fixing it with the two blocking screws. In daytime, point the instrument towards a terrestrial object at least 500 meters distance and easily recognizable (a lamppost or aerial etc). Turn the focusing knob slowly using the focusing tube at its greatest or shortest length as necessary until you have obtained a sharp image of the object to be observed.

Where it proves impossible to get the object in clear focus, repeat the above operation and bring the object under observation to the center of the field of vision of the telescope. Look through the finder and, if the object is not in focus, work on the regulation system (on the ocular or objective) until you have obtained a clear, sharp image. If the object you are observing with the principal telescope is not at the center (fig 2a) of the finder, it will be necessary to bring it into line by turning the regulating screws on the finder stand.

Depending on the model, this will involve either tightening or loosening the screws delicately (using a screwdriver for the reflex model) bringing the image towards the center. When the object is exactly at the center (fig 2b) your finder will be regulated. Repeat the procedure substituting the ocular with one of shorter focal length. A greater degree of magnification will ensure a greater precision in alignment. Now the finder can be used for a rapid aiming at whatever celestial objects you wish to study with your telescope.