After i received the coma corrector, last night, i mounted the 750mm Newton Telescope that came "free" with my new mount (used, very good condition), to test/compare-shoot M42 (Orion Nebula) again. The seeing was about equal as two nights before, when i used the semi-broken 430mm Refractor.
I threw a third of the image frames away, then stacked the better ones. Typical Newton Telescope "4-star" artefacs, many seem to tolerate them and even think they beautify the starlights (compared to dot-shapes from the lens based telescopes). There are artefacts from one blade that holds the central mirror in place, in the right top of the images, i have to research this further, may be user error or mechanical/technical (both fixable) error(s).
One major user error was to expose each of the images for too long, so the lights in the center of the nebula are blown out heavily. I need to remember to choose exposure time based on object magnitude/brightness.

Nevertheless, i'm satisfied with the results: