Laser Collimation of Newtonians The subject tends to generate a lot of heat and smoke with very little illumination when it comes up on Internet discussion groups. This is because people start with different basic assumptions and then tend to talk past each other in what appears to be total disagreement. A few years ago a long running thread on the BIGDOB discussion group displayed an amazing array of debating tactics. The final "winner" would appear to be the one who posted the last message in the thread. Of course with two or more participants with plenty of time on their hands, the debate could go on forever. All this debate accomplished was to scare amateur astronomers into buying expensive refractors that lack collimation screws alltogether. Added to this is the emergence of people with a commercial interest in the debate. Howe Glatter is gentleman who lets his product reputation speak for itself, but other vendors lurk on discussion groups and flame anyone who offers an adverse opinion of their product. This is not exactly First Amendment behavior. Don Colton's lecture was good up to a point, but he had a lot of ground to cover in a short time and so he had to limit debate and gloss over some points. Chuck Hards brought up one in that lasers themselves need to be in collimation to be of value. A common reply to this problem is to "buy a really expensive one" and that will solve the problem. A better approach is to set the laser in a pair of v blocks on a sturdy table, aim it at a wall that's the focal length of your telescope away from the laser, roll the laser around in the v blocks and measure the radius of the circle the dot traces on the wall, if it's more than millimeter the laser is defective. If you bought it that way you should return it. My own collimation method comes from having used Newtonians before the center spot or the laser were invented. I'll save that for another post. DT ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ