Stacking while light DSLR images with AS3!

[Pappis]

First time poster (but long time lurker) here!

I've been imaging the Sun with my 6" Newton and Canon DSLR for some years, using Baader AstroSolar OD5 and BelOptik UV/IR-KG3 filters. I shoot typically 100-500 images, no video. I have converted my RAW images to TIFF with some preprocessing in Canon DPP, centered and cropped with PIPP (with or without histogramm normalization), and stacked with AS3! (10-50% of lights). Most typical setting involve Surface Stabilization, Improved Tracking ON or OFF, Expand/Cropped, NR 4-5, Local AP, Double Stack Reference with Auto Size. I use sunspots as analysis alignment points, with quite small sizes (mostly 3). In stacking I use 1000-10000 multiscale alignment points (size 48-104). I do frequently get checkerboard-like stacking artefacts, especially near the edges. I think I used to get less of them, but I'm not sure. Seeing seems not to affect this.

How do I reduce those artefacts?

[marktownley]

Hi there and welcome to the forum Pappis.

Do you have cropped selected in AS3? Maybe post up a picture of the artefacts then we can see exactly what they are.

Mark

[Pappis]

This is a quite typical example of the artefacts I get. I have not seen any difference, if I use Cropped or Full Area.

[Montana]

A very warm and sunny welcome

Mmmm it looks like there is either too much movement going on there between frames and not a significant sunspot to lock the stacking software on to. Maybe you should align the frames in ImPPG first to get them all more aligned before adding the frames to stack in ASK3?

Alexandra

[Pappis]

The images were acquired on 20th May 2021, so it had one big sunspot (AR2824).

I centered and cropped all the images using PIPP.

[marktownley]

Hi There.

I think it is because it is so featureless, the DSLR isn't picking up on any granulation that would help to lock on with tracking the alignment points.

You might get better results just taking a single frame image.

Mark