>>>Coma is an optical aberration that shows as the bending or bluring of
straight lines or the smudging of point sources of light. Stars are
perfect point sources of light, so a star test is "simply" taking a
picture of stars. I say "simply" cuz it ain't so simple <g>. However,
once you get the mount and guiding part right, and a good dark place with
no clouds during new moon and not windy you set up the camera, set the
lens wide open and open the shutter for 5-10 minutes or so, depending on
film speed. Progressively stop the lens down, adjusting exposure time
(accounting for reciprocity) then evaluate the results.<<<
"Mount[ing] and guiding" is like, putting the camera on a star tracker?
Otherwise, any exposure over, say, 30sec, will show star trails.
If it doesn't require a tracker, then I'm up for it.
/Acer Victoria
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