Re: ATM Mount performance: A common frame of reference

["Arjan te Marvelde (ELN)" <Arjan.te.Marvelde@eln.ericsson.se>]

>     I suppose measuring linear amplitude of vibration at the 
> focuser will be

Suppose you measure 0 amplitude at the focuser, would the scope then be valued as excellent? Some other part (e.g. secondary) may at the same time be vibrating so much that it destroys the actual view through the eyepiece. 

Alternatively, the precise impact place of the "calibrated knock" can have big effect on the vibration output. Between scopes of the same type of construction this may be a smaller issue, but it will definitely count between different designs.

Hence, in comparing scopes or scope designs for vibration immunity, it is close to impossible to define a standard test based on a calibrated knock and a measuring device. In my opinion, the craftmans' experience and the experience at the eyepiece, in an ad-hoc comparison, will say more than a measurement.

Regards,
Arjan te Marvelde