Quote:
Originally Posted by Gama
The CDK has NO optical axis because it uses a spherical secondary, and so has a huge centering tolerance. So unless the mirror falls right out of the frame, its still centred.
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Only the secondary mirror has no optical axis if it is possible to tilt it exactly in translation of its front surface ( which is never in reality possible) . The primary mirror optical axis and correcting lens set must in a corrected DK be initially centered to the optical axis by a fraction of a milimeter. 'Decenter tolerance ' is _not_ the same thing as 'optical spacing' tolerance : you seem to confuse the two.