|
You can work with the defocused star and secondary shadow - no need to look down the front of the tube for concentric circles. You need to center the secondary shadow by adjusting the collimating screws, but each time you make an adjustment the star should be re-centered. Once the shadow is centered you should have reasonable looking images. From here you can move on to high power in-focus collimation of which I have no experience due to my unstable atmosphere. On the odd occasion I've been able to go to high power but I'm too excited about observing to bother collimating.
If you happened to have a laptop and digital imager you might be able to observe the secondary shadow adjustments on the screen while adjusting the screws - I haven't tried this though as I can reach the front of my 8" sct while looking through the eyepiece.
|