Sunspots 25th September

[michaelmorris]

Here are my latest efforts at white light solar imaging. Seeing was seriously lousy. Avistack couldn't cope with the very poor seeing on the two close up images, so they were processed in Registax.

[Nick Smith]

The close-ups have come out very well nonetheless Michael

Cheers

Nick

[brianb]

Nice work!

Avistack couldn't cope with the very poor seeing on the two close up images

That surprises me ... I find Avistack gets better relatively to Registax the worse the seeing gets. Difficulties with alignment? Try changing the parameters - slows the thing down but the effort is usually worthwhile.

[michaelmorris]

Nice work!

That surprises me ... I find Avistack gets better relatively to Registax the worse the seeing gets. Difficulties with alignment? Try changing the parameters - slows the thing down but the effort is usually worthwhile.

Hi Brian

Normally I would agree with you. However, I am finding that for solar images, Avistack seems to lose alignment on a few alignment points when the seeing is lousy. I then end up in either tram lines and/or fuzzy areas on the final image.

If this happens, I just do single point or a few multi-point alignment points in Registax.

I could probably fiddle with a few parameters on Avistack to fix this but my knowledge of Avistack is less than that of Registax. It would take quite a time to get my head around. With my old machine it takes nearly an hour to process a single AVI in Avistack and at the moment I can't face spending a day fiddling with it. Do you know what setting I should be looking to tweak and in what direction?

The setting I tend to use are:

Reference Point

Correlation Area Radius = >25 to 40

Smoothing factor = 2 or lower.

Image

Smoothing Factor = 5

Minimum Distance = 10

Search Radius = 4

Correlation Area Radius = 10

Quality Area Size = 25

Quality Cut off = 15%

[brianb]

You're obviously using a different version of Avistack ... I'm still on v1.81.

In bad seeing you need to increase search radius - 8 is typical for me. That slows things down but you can gain a lot of speed with insignificant quality decrease by increasing minimum distance, I tend to use 24 or 30. You may also need to increase alignment area size if you're getting alignment issues (which should show up in the graphs produced in stage 1).

[michaelmorris]

Brian

Thanks for the tips. I'm still on version 1.74. I feel an update coming on ...

[GuillermoBarrancos]

You guys not using Avistack 2.0 yet?

It's lightning fast compaired to previous versions.

I got totally fed up with Avistack 1.xx as it was so terribly slow compaired to Registax.

But Avistack 2.0 made all the difference. The post processing in this new version is also really impressive.

My last series of Solar images are all done with Avistack 2.0.

[brianb]

You guys not using Avistack 2.0 yet?

It's lightning fast compaired to previous versions.

No it's not ... it's just that the default settings are much more aggressive.

There's a big learning curve between v1.81 & v2.0 which I haven't found the time to go up. (A lot more settings which I don't understand!) My first Avistack took 11 hours to process, now I'm routinely getting ~10 mins with v1.81 when seeing conditions are reasonable, and I understand exactly what I'm doing. So what if it takes a couple of hours to "rescue" an image made in awful seeing, it's better than not getting a result at all.

The big advance in v2.0 appears to be the automation, that would be useful for e.g. multi-pane mosaics but I usually want more control than batch operation gives me.

[Joe gray]

These look awsome, I really would love to get into solor imaging