Dmelv

Thanks for your speedy and courteous responses - fellow astrophotographers Duane

ok here's my confusion - still not understanding this fully although I am shooting deepsky photos and getting some results if back focus distance is not quite "Right" will I be able to still line up the diffraction spikes using a Bahtinov mask to the exact centering on a star by using the refractor drawtube focuser - but still not have optimum focus for my photos? Is one focus setting, say on Arcturus, good enough to continue imaging the Lagoon nebula without touching the drawtube focus. Does one focus fit all objects? Does one back focus fit all objects? I am using a refractor with a field flattener - so the draw tube focus does not affect the camera image sensor in the same way with focusing movement as it would without the flattener is this a true statement? I think the back focus is measured from the flattener but where? from the end or from the flange shoulder I.E. do I include the threads or not? The final dilemma. Can one focus on a distant object in the daytime and adjust their back focus by either adding a mechanical helical focuser between the camera and flattener or adding threaded cylinder spacers? If the telescope drawtube will focus on an object in the daytime with room to spare on either side, is this ok to use this backfocus for the stars? I added spacers until I have 55mm from the flattener shoulder to the camera sensor. The sensor is recessed back from the edge of the camera front by 17.5mm so I subtracted it from 55mm to get 37.5mm. Is this right or am I doing it all wrong? My photos seem to be in good focus but I am actually not certain if I could do better. I want a high degree of perfection or else why would I even try to take a photo. So that's the epistle. I am learning as I go here

Has anyone had experience setting gain with the Orion G26 camera in AST? No matter the gain I choose for my exposure plan, AST decides to use gain = 100 and tells me my gain choice is not supported. I am trying to set unity gain or at least a gain way less than 100. Anyone out there who could tell me what to do to make this software work for me? I am using AST build 3.87. Thx!