Expert: Paul Wagner - 11/1/2005

Question
Hi:
I wrote a few days ago about a reflector 4.5" f/4.4. I was trying to look at Venus, but the planet appears a little bit fuzzy, and kind of blurred. I am not overpowering, could this be due to collimation? I have not collimated the telescope since I got it. Once in a while the image also appears kind of double, not a lot, just little. I am scared that it could be the quality of the optics, I bought the telescope a little bit cheap.
I also wanted to know if there is a cheap and effective tool to collimate my telescope.


Thank's for your time and your knowledge.

Answer
Hi Alex:

Venus is just about the worst thing to use for collimation---it is fuzzy anyway, and often is low on the horizon, so that the atmosphere makes the situation even worse. The best thing is a nice bright star--high in the sky.  Look at it as you move the focuser in and out of focus.  It should be symetrical on either side of focus, and resolve into a pretty small bright dot. If things look elliptical or cone-shaped, then there is a chance you need to collimate.  If the images are all pretty circular, the your collimation is probably pretty good.  

The double image may be from a turned edge on the optics ( you can't fix that) but it may also be from internal reflections in the eyepiece.  Try moving your eye around a little bit when you see this.  If it disappears, it's the eyepiece reflection, not the primary optics.

Paul Wagner