|
[QUOTE=multiweb;1233462
You can use an artificial star no problem to collimate during the day. You'll need at least 20m or 40m line of sight on a grassy field to minimise seeing. It will get you ball park.[/QUOTE]
I believe collimation using an artificial star can be used to precisely collimate a SCT if it is done correctly. The distance of the artificial star is of importance as the diameter of the star in arc minutes must be smaller than the resolution of your scope, after all we can't resolve a star as a disk. For this to happen the physical diameter of the artificial star must be unresolvable at the distance it is observed. For an 8" scope using a common diameter star this would be in excess of 40 metres. Seeing and convenience are the best reasons for collimating this way. It is rare for seeing to be good enough to observe a star at high power for collimation .
Philip
|