Weaver209

Hi all! Been trying for months to get sharp stars through my ASI533MC-Pro on an 8"RC scope and still not getting it right! I managed to get lovely sharp stars on my Canon 60D before this new purchase, so i'm struggling to see what may be wrong. Few things i've done listed below: - Checked collimation every session both indoors with a cheshire and then on a star near zenith. - Use Bahtinovgrabber and a mask to make sure focus is as close as possible to perfect. - Tried both with and without focal reducer. - Checked guiding, which is always under 1". - Checked polar alignment with sharpcap and levelled mount. Issues are annoying showing up on subs of pretty much any length, 60-600s. I've attached a couple to show. Any help or tips are hugely appreciated, this is my biggest learning block so far!

I've been using a StellaLyra 8"RC for a few months now, and with my Canon 60D it worked perfectly. Now I've got an ASI533-MC Pro, things are much more complex! I'm struggling to get stars in focus or round enough for DeepSkyStacker to stack the images properly, and other than the possibility of dew on the camera, I can't see why this might be. Using a Bahtinov mask I'm getting perfect focus on bright stars, but the smaller stars in images of M51 recently seemed a bit naff. I therefore wanted to make sure I had my backfocus right! According to the GSO online manual, the backfocus should be 254mm to the camera sensor from the rear cell, and I think I've managed this. If using the Astro-essentials 0.75x reducer, I need 80mm backfocus to the sensor, but where does the reducer itself go in the train? do I need to put it in the train with the same spacers on before the focuser? Sorry this is all a big learning curve!