M13 good and not so good

[alcol620]

Following lots of help on this site and the tutoring of Doug on budgetastro.net. I have used Firecapture, then Deepskystacker and Photoshop to produce the following images of M13. Using EQ5 mount Celestron 8SE scope and a ASI120MC camera.

 

The images were taken on different nights, both nights had reasonable seeing - I think. The second image looks to be higher magnification, I may have not added the .5X focal reducer to the camera! Both images were achieved with exposures of around 50X 5 seconds.

 

Would welcome an comments especially on what looks like the out of focus image.

 

[jtlandreneau]

The one on the right looks very much like my first attempts at M13 before I was autoguiding and had proper focus. The cheaper option right now, which I would hazard a guess is the bigger issue, would be to fix the focus with a Bahtinov Mask. I bought one for around $15 (which the way our economy is right now is probably around 2 pound for y'all across the pond  )

At 5 seconds I kinda doubt tracking is a major issue, so I'm going to through this at you from left field - it looks like you might have some coma issues too. the bahtinov focus might show that to not be true, but if it is I would make sure your telescope is properly collimated , and your target is centered on your imager

[jtlandreneau]

I attached my M13 pictures, first is without the mask and with coma, second is fixed coma and focusing with autoguiding.

[alcol620]

 jtlandreneau

Thanks for your comments. I have the mask but didn't think to use it!

Obviously a big differences in your images.

I have seen comment about coma and will now check it out