Camera/ optics or other

[geordie85]

After some pixel peeping of my latest images with my new QHY183C and WO star71 I noticed the colour wasn't quite in the stars. So last night I cranked up the offset, pointed at Vega and noticed a kind of "starburst" effect coming out from one side.

I spent a good 3 hours trying to diagnose the problem, adjusting the built in tilt adjuster, loosening and tightening the focus tension screws and anything else I could think of that may be causing this effect. But to no avail so here I am asking the knowledgeable men and women of SGL for help.

Turning the camera would change the direction of the "starburst" which makes me think its not the scope. It was a costumer return to FLO due to collimation issues but was checked, tuned and fixed by ES Reid so I doubt it could be the scope, but it could be.

Attached is a screenshot of a 10 second exposure in SGpro.

 

[michael.h.f.wilkinson]

I am not quite sure what you mean when you say the turning the camera changes the direction of the pattern, but if you rotate the camera, and the patter stays the same on the sky, i.e. it points towards the same stars, but rotates in the opposite direction with respect to the image frame, then it is not the camera, but the optics. If the pattern stays in the same orientation with the image frame, then it is purely the camera, I would say. If it is some mix, then there is something amiss with the combination (and I do not know what that could be beyond things you have tried).

[geordie85]

2 minutes ago, michael.h.f.wilkinson said:

I am not quite sure what you mean when you say the turning the camera changes the direction of the pattern, but if you rotate the camera, and the patter stays the same on the sky, i.e. it points towards the same stars, but rotates in the opposite direction with respect to the image frame, then it is not the camera, but the optics. If the pattern stays in the same orientation with the image frame, then it is purely the camera, I would say. If it is some mix, then there is something amiss with the combination (and I do not know what that could be beyond things you have tried).

What I mean is in the above image the "starburst" is pointing to the right. When I rotate the camera 90 degrees clockwise, the direction of the burst also rotates 90 degrees clockwise and instead of pointing right, it points down.

[michael.h.f.wilkinson]

1 minute ago, geordie85 said:

What I mean is in the above image the "starburst" is pointing to the right. When I rotate the camera 90 degrees clockwise, the direction of the burst also rotates 90 degrees clockwise and instead of pointing right, it points down.

So it stay put with respect to the long axis of the camera image, I understand. That sounds more like some bleed issue in the camera (odd, because it is not CCD, which are more prone to bleed), or there might be some scatter issue in the Bayer mask. Do you have a different optical system to test it on? If it shows the same pattern, it is almost certainly a camera issue

[geordie85]

4 minutes ago, michael.h.f.wilkinson said:

So it stay put with respect to the long axis of the camera image, I understand. That sounds more like some bleed issue in the camera (odd, because it is not CCD, which are more prone to bleed), or there might be some scatter issue in the Bayer mask. Do you have a different optical system to test it on? If it shows the same pattern, it is almost certainly a camera issue

I do have a 200p I can test it on next time the skies are clear, whenever that might be.

Is there any way I can test this without needing a clear nights sky?

[michael.h.f.wilkinson]

Just now, geordie85 said:

I do have a 200p I can test it on next time the skies are clear, whenever that might be.

Is there any way I can test this without needing a clear nights sky?

No idea, really, unless you have an artificial star at your disposal

[geordie85]

Just now, michael.h.f.wilkinson said:

No idea, really, unless you have an artificial star at your disposal

I don't unfortunately, guess I'll just have to be patient.

Thank you, I really appreciate your help 

[vlaiv]

3 hours ago, geordie85 said:

What I mean is in the above image the "starburst" is pointing to the right. When I rotate the camera 90 degrees clockwise, the direction of the burst also rotates 90 degrees clockwise and instead of pointing right, it points down.

 

3 hours ago, michael.h.f.wilkinson said:

So it stay put with respect to the long axis of the camera image, I understand. That sounds more like some bleed issue in the camera (odd, because it is not CCD, which are more prone to bleed), or there might be some scatter issue in the Bayer mask. Do you have a different optical system to test it on? If it shows the same pattern, it is almost certainly a camera issue

If it points down (on computer screen) - would that not mean that it is optics? If it were camera related, and you turn camera - since screen is aligned with the camera - flare should stay the same and point to the right while FOV (stars) rotate?

[michael.h.f.wilkinson]

1 hour ago, vlaiv said:

 

If it points down (on computer screen) - would that not mean that it is optics? If it were camera related, and you turn camera - since screen is aligned with the camera - flare should stay the same and point to the right while FOV (stars) rotate?

I interpreted the feature rotating clockwise when the camera was rotated clockwise to mean that the OP meant he took into account the actual orientation on the sky, otherwise rotating the camera clockwise would rotate the feature counter-clockwise, I would think

[vlaiv]

17 minutes ago, michael.h.f.wilkinson said:

I interpreted the feature rotating clockwise when the camera was rotated clockwise to mean that the OP meant he took into account the actual orientation on the sky, otherwise rotating the camera clockwise would rotate the feature counter-clockwise, I would think

I'm not sure that rotation direction can be used as reference because different software interprets up/down direction in fits differently (two different coordinate systems used - screen space where Y axis is down, and "natural" where Y axis is up). I've seen this in quite a bit of software - images often end up being inverted. I would also suspect that screen rotation vs camera rotation depends on scope type (refractor vs reflector).

On the other hand, I'm pretty sure that camera "space" artifacts don't change direction at all when you rotate camera - think amp glow, it is always in the same place in frame on screen, regardless of frame orientation, so if flare rotated when FOV was rotated - it is optics caused.

[geordie85]

Thanks for all your comments. Unfortunately I didn't take any exposures as I was using frame and focus in SGPRO for quicker download speeds.

I'll try it with my 200p or my Samyang 135mm lens the next opportunity I get to see if I still get the flaring.

I really hope it's not the scope as I've had it for almost 2 years so probably out of warranty