12 replies to this topic

[BackyardAPas_teen]

I outlined it in blue. I currently use an askar fma 180 pro, modded canon rebel xsi, and t ring. what causes this, and how do I prevent it?

Edited by BackyardAPas_teen, 17 February 2025 - 10:34 AM.

[sharkmelley]

Did you intend to upload an image?

[Sincos]

Just by the wording of question with no supplied picture , sounds like chromatic aberration.

[BackyardAPas_teen]

sorry, it seems the image wasn't attached. it isn't chromatic aberration, is around the edges of the images. Il post it here.

[michael8554]

I see dust bunnies on the images, are you using Flats ?

[BackyardAPas_teen]

No. Only lights. That I can fix. What is the green purple thing on the outer edges? Specifically the bottom and top, a bit on the right also

[ayadai]

It might be stacking artifacts due to target wandering. Are you recentering after drift?

[BackyardAPas_teen]

All I do is set it up, and leave it there to take images ( lights only. ). then I bring it inside and stack the images, as well as color calibrate and background extraction in siril

 

I use a star adventurer 2i pro pack, no guiding system.

[ayadai]

All I do is set it up, and leave it there to take images ( lights only. ). then I bring it inside and stack the images, as well as color calibrate and background extraction in siril

 

I use a star adventurer 2i pro pack, no guiding system.

That likely explains it. When stacked, the alignment varies significantly from frame to frame, resulting in edge artifacts. Flats may help a little, but with your current setup, you'll need to crop.

Edited by ayadai, 19 February 2025 - 05:27 PM.

[SpaceMax]

I am getting the same sometimes even with perfect guided and dithered exposures.

Since dithering is essentially drift on purpose, would that not be counterproductive? Or is the effect caused by something else?

I noticed that I see it when using StarTools to stretch. But I don’t see it in the same stack when stretching in PS.

Can the OP try stretching in another programme and see if that has any impact?

Edited by SpaceMax, 20 February 2025 - 05:03 AM.

[ayadai]

I am getting the same sometimes even with perfect guided and dithered exposures.

Since dithering is essentially drift on purpose, would that not be counterproductive? Or is the effect caused by something else?

I noticed that I see it when using StarTools to stretch. But I don’t see it in the same stack when stretching in PS.

Can the OP try stretching in another programme and see if that has any impact?

Dithering is typically only 5 pixels or less, so any edge artifacts would be far less obvious. SIRIL might work better for you. I don't think that anything short of cropping will address the issue for the OP.

[BackyardAPas_teen]

Ok, thanks for all the help! So if I were to get a guiding system with a better mount, it would fix the problem?

[ayadai]

Ok, thanks for all the help! So if I were to get a guiding system with a better mount, it would fix the problem?

Before diving into the rabbit hole and endless expenditure of gear acquisition, you might want to try processing a new set of images with calibration frames in SIRIL. This guide will help you get up to speed with calibration frames from your camera. The experience you gain will be fully applicable should you decide to upgrade.

 

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If, however, you have a pile of cash lying around and oodles of time:

 

A solid mount is the foundation for any AP rig, so it's the best place to start. Guiding is helpful for ensuring that your images have round stars that are not bloated.  A good mount and guiding alone, however, will not fully address the issue of drift (note that malfunctioning guiding can sometimes actually contribute to drift!).

 

Note that while you can use your Canon with various control software, it may be finicky, as the majority of these programs are designed around cameras that  produce files in the FITS format. You may find this thread interesting.

 

NINA and other control software suites have the ability to plate solve images as they're acquired and determine if the target has drifted within the frame. The software can then automatically recenter the target when that occurs. In order to use this ability, you'll need to connect a camera and an AP-capable mount to a computer via a USB cable, install all applicable drivers, and configure NINA or the control software of your choice.