Compare the pair...

[Peter Ward]

Think I've finally managed to tame this SHG.

My thoughts are the data produced is very good, with excellent contrast, but
cannot deliver the ultra fine resolution of Etalon based systems.

This mainly due the images being built from hundreds of linear scans (which take time)
and with any atmospheric disturbance between each line you end up with a slight "ripple" in the final image.

That said....gee....a 90m Etalon is serious $$$ these days....

...to get a similar level of resolution for about $A 1K is previously unheard of "bang for buck"
and you can explore many more spectral lines.


The link is here

[h0ughy (David)]

You can tell you're retired, time effort and results

[Peter Ward]

Originally Posted by h0ughy

You can tell you're retired, time effort and results

Ta. SHG's are quite terse in their requirements for accurate collimation
and focus of three different elements.

But when you have them all well converged, and have a camera that can sample in the 100's of frames per second,
the result is indeed not too shabby.

[Maurice]

Excellent stuff Peter!

Like I've said in my other post - you've leapt ahead dramatically in image quality in just a few days...well done.

I look forward to seeing some images at other wavelengths from you soon too.

Cheers
Maurice

[Peter Ward]

Originally Posted by Maurice

Excellent stuff Peter!

Like I've said in my other post - you've leapt ahead dramatically in image quality in just a few days...well done.

I look forward to seeing some images at other wavelengths from you soon too.

Cheers
Maurice

Thanks Maurice. It's been an interesting and rewarding exercise to date.
Stacking multiple scans is the next logical step...the rub for me is I can grab 2000 9 megabit frames, with a double-stack Etalon, in about two minutes.

....but scanning with a albeit a narrower band SHG, just a dozen frames takes quite a while longer, with solar rotation/activity blurring details if you push capture intervals beyond that.

As for other wavelengths, absolutely!
That's where the real fun might begin

[multiweb (Marc)]

Very cool Peter
Looking forward to the other wavelengths too.

[Peter Ward]

Originally Posted by multiweb

Very cool Peter
Looking forward to the other wavelengths too.

Thanks Marc. I've tested the Ca K end of the spectrum already.
It clearly works...but with mixed results as I need to recalibrate the system due chromatic aberration shifting the focus significantly from red to violet.

One step forward, two back

[Gallifreyboy]

They are very impressive. After mucking around with a Quark in the past with some underwhelming results I recently purchased the Skywatcher 76Ha and the ASI678MM is a perfect pairing for that. I well and truly have the solar bug at the moment. Pleased to see if I go down the SHG path in the future it will serve a good purpose.
Also you must have a very special SHG, your image suggests it is taken on 20 Feb 2025, tomorrow

[Peter Ward]

Originally Posted by Gallifreyboy

They are very impressive........ suggests it is taken on 20 Feb 2025, tomorrow

Opps. I was checking my tickets to see The Corrs in Sydney on the 20th...
Freudian slip for sure

[gregbradley]

I like the resulting image with the new system. Those bright areas look cool.

Greg.

[Peter Ward]

Originally Posted by gregbradley

I like the resulting image with the new system. Those bright areas look cool.

Greg.

Ta.

The contrast of the SHG is impressive, that said , chromospheric "candle flame" structures and spicules along the limb are all but absent. (hard to see in the linked image). Larger aperture etalons have the advantage there.

That's not to say SHG imagery can't be improved upon....and this is something I'm still exploring. It will be interesting to see what differing scanning speeds and stacking software can do....when the weather clears!

[multiweb (Marc)]

Originally Posted by Peter Ward

Ta.

The contrast of the SHG is impressive, that said , chromospheric "candle flame" structures and spicules along the limb are all but absent. (hard to see in the linked image). Larger aperture etalons have the advantage there.

That's not to say SHG imagery can't be improved upon....and this is something I'm still exploring. It will be interesting to see what differing scanning speeds and stacking software can do....when the weather clears!

If you manage do derotate one stack then you could do a bicolor rendition. Like A AB[x%/y%] B. See what works best to increase contrast and highlight matching features. Bit of fun for a rainy day.