Over the 2021/2022 winter I bought a ZWO OAG. I spent those cold months figuring out how to incorporate this device into my set-up. My post Adding an Off-Axis Guider to my Set-up goes into lots of detail regarding back focus requirements for my two telescopes (Celestron 8” EdgeHD SCT and a Skywatcher BK80ED refractor). It wasn’t until May that I finally got a chance to use my set-up “under the stars”. Don’t let your imaging camera drop to the ground! My post “First Light” using an Off-Axis Guider explains…
Category: Focus
Issues surrounding how to focus a telescope and troubleshooting focusing
My LIGHT Table Solution
In 2021 I bought a LIGHT Table on Amazon which I believe works very well. It also caused me to develop a method for taking FLATs that is quick, accurate and easy. Background A key aspect of Astrophotography is taking quality FLATs. Vignetting caused by lens or telescopes is not simple. Even though your telescope, focuser, filters and camera all look like they are perfectly aligned…they typically are not. The center of your LIGHT frames is not always the location where the vignetting is at it’s minimum. This “sweet spot”…
Focus or Guiding causing high FWHM?
I am revisiting some of my astrophotos to clean them up for publishing. In many cases it’s becoming obvious that my stars are not as sharp as they should be. I struggle trying to determine whether the issue is focus or guiding. I always focus using a live 8-bit video stream and autofocus to yield the smallest stars. When I look at my photos later I notice that the FWHM values vary from night to night and yet, in comparison, my guiding is fairly consistent. If FWHM varied with guiding…