Field rotation?

[Rustang]

Ive known my stars in the corners of my images have always been pants so i felt its time to see how to improve this. The strange thing is, if you look at my image it looks like field rotation if you notice the direction of travel of the stars in the corners!? I use an app to see where to put Polaris for Pola alignment so I cant see how that could be so far out and I'm guiding also so any advice would be greatly received as always.

 

 

Edited July 23, 2021 by Rustang

[Astro Noodles]

Is the scope slipping in its rings, or the camera slipping?

[NorthernAstro]

What type of mount is it? If it is an alt az mount, the field will rotate over time, if it is an equatorial mount I am sorry and I can not help you.

[Rustang]

10 minutes ago, Astro Noodles said:

Is the scope slipping in its rings, or the camera slipping?

Could be but its pretty hand tight in its rings, i never know how tight to go though!

[Rustang]

4 minutes ago, NorthernAstro said:

What type of mount is it? If it is an alt az mount, the field will rotate over time, if it is an equatorial mount I am sorry and I can not help you.

HEQ5 Pro

[NorthernAstro]

Just now, Rustang said:

HEQ5 Pro

Ah nevermind, sorry. I don’t have much expertise in this so I can’t help further. Thank you for telling me the mount.

[Astro Noodles]

2 minutes ago, Rustang said:

Could be but its pretty hand tight in its rings, i never know how tight to go though!

I can't think what else could be causing it, What about the camera, is that secure?

[Rustang]

10 minutes ago, Astro Noodles said:

I can't think what else could be causing it, What about the camera, is that secure?

Camera is definitely secure. If it happens to be the pola aligment thats out (i cant see how though) could that cause it even with guiding?

[Astro Noodles]

2 minutes ago, Rustang said:

Camera is definitely secure. If it happens to be the pola aligment thats out (i cant see how though) could that cause it even with guiding?

It's not PA. If it was, the streaking would all be in the same direction, and it would be across the frame. What sort of scope are you using? are you using a field rotator?

[symmetal]

If you have a field flattener in the image train you can get this effect with incorrect flattener sensor spacing distance, generally this effect is with the distance too great.

6 minutes ago, Rustang said:

Camera is definitely secure. If it happens to be the pola aligment thats out (i cant see how though) could that cause it even with guiding?

Yes if the polar alignment is significantly out, you will get visible field rotation in the image and it will rotate around the guiding star.

Alan

[Rustang]

6 minutes ago, Astro Noodles said:

It's not PA. If it was, the streaking would all be in the same direction, and it would be across the frame. What sort of scope are you using? are you using a field rotator?

Yeah I'm using a reducer so it could well be that, that's not correctly spaced!

[Rustang]

2 minutes ago, symmetal said:

If you have a field flattener in the image train you can get this effect with incorrect flattener sensor spacing distance, generally this effect is with the distance too great.

Yes if the polar alignment is significantly out, you will get visible field rotation in the image and it will rotate around the guiding star.

Alan

I'm using a reducer so as said above, it could be that not correctly spaced, I will have to have a look at that when I get a chance.

Edited July 23, 2021 by Rustang

[newbie alert]

Looks like spacing to me.. 

Edited July 29, 2021 by newbie alert
Added image

[ollypenrice]

On 23/07/2021 at 20:13, Astro Noodles said:

It's not PA. If it was, the streaking would all be in the same direction, and it would be across the frame. What sort of scope are you using? are you using a field rotator?

No, as Alan says, a poorly aligned mount will show rotation around the guide star. That's possible, certainly, but I think it more likely to be too much distance from the reducer as per Newbie Alert's second diagram.

Olly