Jupiter - focus/collimation?

[animaal]

My latest image of Jupiter (& Ganymede) from the weekend. My first time trying mono + filter imaging.

A question for the more experienced, how can I tell from an image if I am suffering from Collimation error rather than bad focus?

Thanks.

 

[Woolnut]

Nice image! What kit have you used to achieve this?

 

[animaal]

5 minutes ago, Woolnut said:

Nice image! What kit have you used to achieve this?

 

Thanks. I used a Celestron C925, ZWO ASI290MM, and 1.25" RGB filters. I found the focusing a bit tricky because I'm not used to seeing a grey image on the screen, so I'm not sure if it's quite "there".