[allan gould]

Been doing a bit of reading lately about SCTs in geeral and in particular about how collimation really does affect the photographic flat plane and ability to see details. And then it occurred to me why a good percentage of us that are getting a little long in the tooth may not be getting the set out of our scopes.
Last week I deliberately mis-collimated my SCT and then by eye on the computer screen re-collimated it using a CCD. By eye I thought, that's perfect but I consistently did not have it done properly when I checked with ALS collimation aid and then it dawned on me that my astigmatism was throwing off my ability to make the circles concentric. It was just a minor effect but at higher powers it become more obvious.
I was wondering if someone else with known astigmatism could check this out and do collimation with and without Al's collimation aid.
Something to think of but anyway I know I now nail it using Al Sheeny's program.