A second attempt at Mars this morning between 4.30 and 5.00 local time with the planet between 5o and 10o above horizon. At least I saw it but I could make out no detail. Pretty good seeing with the outline moderately well defined at times so I thought I'd be able to make out the SPC but no luck. I expect I was being over optimistic with the altitude being in only single figures although I did see a mention of dust storms around Hellas. But I doubt if that's the explanation.
To counter atmospheric dispersion I had picked out a few microscope slides with reasonable figures and knocked up a couple of 2o prisms using uv cured optical cement which were held up to the eyepiece. They helped but a bit more experimentation needed but that will wait until the end of the month.
Magnifications of x60 and x120 with the 8.5'' slow Dob.
Edited by davidc135, 07 May 2022 - 03:33 AM.