150mm MCT f/13, 31% CO
"People say I'm in denial. I disagree."
Friends call me Duane. Compustar C14, Leo Henzl's Custom C8, 6" Refractor Adv. GT mount, 6" F5 Omni XLT Newt., LXD-75 F4 Imaging SN8, Meade 8" F6 Newtonian, EX Dynamax DX6, RV-6 ETX-90 Astro, Meade 2045 4" SCT, B&L 4000 Vixen/Celestron 80mm F11 JC Penny 60mm AZ/ALT Refractor Binos 25x100
-DannyMy warehouseMy Channel
Quote:I could not get Abberator to churn out a model that worked for me.
Quote:I will be the first to admit that your saga has been very interesting...
Quote: Not sure how the KE would "spin."
Quote:If the model is balanced, as Vlad often says it "must" be, then the correction is very good.
"A telescope is either good or cheap, not both" - but sometimes you get lucky!
Quote: how to proceed and when.
Quote: Star Spot test The Spherical Spot test is wonderfully sensitive because it is a null test. This means that when you do the test every part of the mirror is (supposed to be) at the same zone. Any part of the mirror which is at a different zone stands right out. You can get the same results from a complete telescope by using a real star as the light source. Assemble your telescope, wait for some great seeing, and point to a star. You will need a sturdy mount for your telescope. Keep the star centered and remove the eyepiece (dob users usually prefer Polaris). You can start with a knife edge cutting in the cone of light, move the focuser to find the focal point of the telescope. This is a 1D null test and it is very sensitive. Many people have done this before. Now merely replace the knife edge with a very small spot. Since the star is a true point source, you will be able to use a spot as small as 0.001" for greater sensitivity. Bring the spot to the focal point (keep the star centered). There is a null point there which will show you the quality of the wavefront exiting the telescope in graphic detail. But be aware, this test is severe. It tests the entire optical system. Not just the mirrors and/or lenses, but also the air the light travels through. It might even be as brutal as the regular star test (with an eyepiece; it shows the change in the diffraction pattern due to image aberrations). Certainly they should be used together. The star test can tell if you have errors, the Star Spot test will show you most of those errors directly.