has anyone here used an artifical star for collomation? it seems that the point of light for my scope at 100 feet would have to be less than .15mm in size! anyone have any methods to create an artifical star? has anyone used the picostar artifical star? it seems very pricy
I have an article on collimating / star testing with an artificial star by Richard Berry (Astronomy Magazine and ATM Mag.) From memory, you'll need to place it a good bit further away drom your scope than 100 feet. I'll try and dig it out for you... but remind me if you don't hear anything by tomorrow!
Even a 500mm scope would only need distance of 38 metres.
I never had any real success with homemade artificial stars but I did see an article recently where someone created on using a bright diode and a piece of optical fibre in an enclosure.
It's your lucky day - I found them in the first file I put my hands on! I have scanned the two page article and can email it to you if you let me have your address.
Phil.
PS - Instead of using a condenser lens and an eyepiece to manipulate the beam, you could use a couple of objective lenses from a cheepo pair of binoculars or one objective lens and a binocular eyepiece. Fiddle around with the arrangement and see what works. Also, an ultra-bright LED will work very nicely as a light source... as will a low-power red laser pointer (in which case you don't need the first condenser lens - just the second lens to expand the beam.
  