OK, I have all these refractors, and I have no idea how to test them or even collimate a refractor lens. Other than taking them to a lab, is there a simple way to test one?? I'd like to test my Sears 90mm. I guess I should have paid more attention to the postings from before, because I remember seeing something about a flourescent light test, but I don't know if that is for a refractor lens

, and one where you can check diffraction rings, but I'm pretty unsure what I need to do. Any suggestions guys? Thanks for any help, and happy 4th,

Rich