collimation tool for refractorPosted By John Hopkins |
Check this link:
http://www.astunit.com/tutorials/collifrac.htm
And another one (in PDF format):
http://www.skywatchertelescope.net/Downloads/AdjustableLens.pdf
http://www.astunit.com/tutorials/collifrac.htm
And another one (in PDF format):
http://www.skywatchertelescope.net/Downloads/AdjustableLens.pdf