A Collimation issue

[JohnH]

Looks good, a processed crop wuold be easier to see.

Hi Carole,

I have now stacked in Pixinsight, used the automatic Screen Transfer Function histogram adjustment and applied it to the image followed by a bit of vignette removal but nothing else to sharpen or denoise etc.. This is the result:



The stars seem reasonably round into the corners (blame my eyesight).
Regards,

John

[JohnH]

Just thought, I should have used the "Aberration Inspector" script in PI. Here it is showing the corners, mid sides and centre:



Actually,I am quite pleased with that, particularly as the scope did a meridian shift part way through the sequence. A bit elongated bottom right and top left (?) but still a lot better than my previous efforts.

John

[The Thing]

Looking good John, better than I've managed with my TS1506UNC. If you look at my latest image you can see the diffraction spikes in one axis have started diverging - the secondary has moved during slewing and acquisition. It also affects focus at the sides of course. I am working on a spider head design to allow me to use a screw to control rotation so it can be set securely but still allow the tilt adjustments to be made. It'll be 3D printed when I get there. I might go for curved spider vanes while I'm at it then the problem won't show (no diffraction spikes!)

Duncan

[Carole]

That's looking so much better John.  But whilst i enjoyed them I am glad my Reflector days are over.  Refractors are much less hassle.

Carole