Skywatcher EQ5 issues

[Colin]

Hi All,

Last night was first time with a brand new Skywatcher EQ5. Telescope is a William Optics GT71. Camera is ZWO585MC.

Images have a strange circular pattern to them, yet the stars are okay for 3 and 5 minute exposures. Guiding was acceptable

Darks and Biases do not show this issue.

Any advice on possible causes is appreciated???

[Startrek]

At first glance it looks like walking noise caused by some field rotation as a result of poor polar alignment.
It doesn’t look like an optical error in your image train ( I’m a Newt user not a refractor user so others may chime in to confirm that )
How is your Pa error ?
When guiding was the Ra error similar to Dec error or Dec was substantially larger ?
Did you dither your subs with enough pixels ? Dithering is an absolute must in AP
Another possibility is calibration issues but that would generally not cause a circular pattern

Hope others offer more suggestions / advice

Cheers
Martin

[Drac0]

Hi Colin,

Looks like walking noise combined with some field rotation from polar alignment being slightly off. You don't mention what software you are using for capture but in general, look at improving PA if possible, and use dithering between images.

Hope this helps.

Cheers,
Mark

[Nikolas]

What the others said, some field rotation and walking noise. Get the polar alignment right and learn about dithering to eliminate walking noise. The circular patterns are halos caused by something in your imaging train. Looking at the colour of the flame it looks like a cheapy duoband filter in the image train causing the halo