[ATM] ATM: Re: strange (collimation?) problem (2nd)

["David Harbour" <scarab2@cox.net>]

Andy,

How elegant and well thought out:

>Re the 'collimation difficulties' caused by the asymmetrical location of
the
>secondary..easily fixed by adding a masking disk larger than the secondary,
>centered on the OTA. This idea can be expanded to making the mask almost
the
>same size as the primary, so during daylight collimation one sees a thin
>annulus
>of light vs most of the primary. If the eye is centered in the focuser via
>a small
>aperture, any miscollimation of the primary shows up as asymmetry in the
>ring of
>light. Basically does the same thing as a laser but can handle perforated
>primaries.

(from your buddy Dave)


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