Recent Activity

Nikon D5300 vs QHY294C

In 2020 I bought a QHY294C and had lots of opportunities to test out this dedicated cooled OSC astrocam. Up until 2020 I had been using a Nikon D5300 with was HA modified by Kolari Vision. The D5300 and QHY294C are 14 bit cameras. The Ha modification did improve the camera’s sensitivity and I noticed more detail in faint galaxies. I decided to start putting together some comparison images. The images presented here used master DARKs, FLATs and BIAS. The Bubble Nebula was my first comparison. This is a cropped…

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…