Quote:
Originally Posted by astro744
Use a higher power eyepiece as you will get better diffraction rings both in and out of focus. Try racking inward past focus and outward past focus.
See http://www.willbell.com/tm/tm5.htm for some example images of what you can expect to see. Note you are only collimating not evaluating the mirror surface quality so although steady air is best, you can do this in air that is shimmering and in light pollution.
Your aim is to have concentric rings at the highest power you can observe with as any error will be more visible at the higher power. |
Thanks very much. I was just googling some images of star tests and I found something that looks exactly like what I'm seeing. I've attached the image if you get a chance to look at it. It's the one on the top left. Thanks again for the advice - I'll try the 9mm tonight and I bought a barlow so I'll try that with the 9mm also and see how I go. Herschel.