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: Mount
Posts about my CGEM mount
Star Eccentricity and Guiding Accuracy
The Pix Insight documentation specifies that most people would consider a star to be round when the Star Eccentricity is less than 0.42. The equation for Star Eccentricity is a bit convoluted but a star eccentricity 0f 0.42 is also equivalent to a Star Aspect Ratio of 0.91 or a Star Flatness of 0.10. I have chosen to have CaLIGHTs calculate what I call Star Roundness(%) which equals the Star Aspect Ratio multiplied by 100. So a CaLIGHTs Roundness value of 91% equals a Pix Insight Star Eccentricity of 0.42.…
Declination Backlash…my story
I use a Celestron CGEM for my mount. It suffers from roughly 50 arc-seconds of declination backlash…which is big. This causes big headaches when trying to autoguide. I have invented a program I call “Backlash Assistant” which dramatically reduces the effect of declination backlash while autoguiding. The program is synchronized with PHD2 Guiding and operates in parallel with PHD2 to quickly move my declination axis thru its backlash such that my autoguiding barely notices what is happening. So… What is declination backlash? Most mounts use motors coupled to multiple sets…
Differential Flexure…my story
For years now I have been taking long exposure LIGHT frames. 500 second exposures at ISO200 was my goto setting for my Nikon D5300. With my QHY294C I have been using 600 seconds at GAIN=1600 for narrowband LIGHT frames and 200-300 seconds for broadband (LPR filter) LIGHT frames. I have been resisting buying an off-axis guider while focusing my attention on better guiding and a software based differential flexure compensation scheme. I hope to create a post detailing my work on improving my guiding. This post is going to focus…
How I lug around my CGEM mount
I don’t have an observatory so I have to lug my set-up outside and back into the house every time I use it. The mount is the heaviest part so I created some wooden accessories to make this exercise a little less painful. Here I have placed the CGEM mount on a wooden platform and attached a wooden carrying handle. I normally store the mount on the tripod when I am not using it. To move it I will attach the handle and place the wooden platform where I know…