Solar Feature July 5

[TechnoBill]

Hi all,
Its been a while since I have had an oppertunity to do any imaging. Only had a small window today before the clouds came in. I had a quick go at AR 1084.


Regards
Billy D

[sheeny (Al)]

Nice work, Bill!

Al.

[icytailmark (Mark)]

wow thats an awesome picture. What sort of setup do you have?

[Paul Haese]

Looks very nice Bill. I like the detail and colouring. Well done.

[TechnoBill]

Originally Posted by sheeny

Nice work, Bill!

Thanks Sheeny. I need to chat to you about your Full disk mosaics. They look fantastic. I tried a mosaic the other day, a bit overenthusiastic I think 4x6 but when assembled it looked terrible because of the darker shades around the outsides of each frame and the hotspots in the centre.

Originally Posted by icytailmark

wow thats an awesome picture. What sort of setup do you have?

Thanks. That was taken using a Lunt LS60THa with a 2x barlow and a DMK41 mono camera. I also have the option of Doublestacking my Lunt Scope which I did not do here. I find I can get just as much detail / contrast with alot less fiddling around with just the standard scope and no double stacking.

Originally Posted by Paul Haese

Looks very nice Bill. I like the detail and colouring. Well done.

Thanks Paul,
I feel I am still overprocessing my images, but I can't help myself .

Bill D

[sheeny (Al)]

Originally Posted by TechnoBill

Thanks Sheeny. I need to chat to you about your Full disk mosaics. They look fantastic. I tried a mosaic the other day, a bit overenthusiastic I think 4x6 but when assembled it looked terrible because of the darker shades around the outsides of each frame and the hotspots in the centre.

No worries, Bill.

My top tips:
1. Brightness =0
2. Gain = 380 (this gives best dynamic range apparently)
3. Adjust exposure on the middle brightest part of the disk so the max on the histogram is about 225 (roughly).
4. Use same settings for all parts of the mosaic.
5. I've been getting away with assembling the mosaic in PS CS3 after wavelets in Registax. Give it a whirl, but if it doesn't work assemble the mosaic on the unsharpened stack.

Good luck!

Al.

[TechnoBill]

The real issue I had with the mosaic was that there is a hot spot in the middle of each images so the edges are duller than the center. Also I was manually adjusting the scope for each shot so the distances and the overlap varied.
I was thinking to myself wow its a 4000 x 4000 mosica it will look amazing. Reality was a little more depressing. When Assembled it all the overlaps lined up but the edges were all different chades some brighter overlapping darker areas etc like a patchwork quilt.

I have Photoshop cs4 and I will need to learn how to create and apply the right gradients to each frame to try and even the brightness of each frame to the edges so the overlapping areas are not so obvious.
I might try experimenting trying something like a blur function on the image, invert it and trying to use that as an adjustment mask of some kind. I kinda understand the theory but I am not sure how to put it into practice.

Bill D

[sheeny (Al)]

Hmmm. I'm glad to say, Bill, that I don't suffer from that problem. The SM40, ED80, B1200 combo is exceptionally flat wrt gradients. The PST has a bit of a sweet/hot spot, so I'm really enjoying using the SM40 on the ED80.

I guess I can't assume that a larger Ha filter will still be flat when I go to upgrade...

Have you tried to devise a way to take a flat frame with a Ha scope?

Al.

[TechnoBill]

Hmm taking flats the traditional way with the solar scope would be quite hard, as I tend to fine tune the etalon once on the sun to highlight certain features and this moves the hot spot. Thats why I was looking at using the blur / invert functions to create a mask from the brightness of the actual image. I Just have to read up on the right way to apply the adjustment layer to effectively remove the gradient. I might try applying it as a flat in AVIStack.

As my lunt is a Double stack, I have a spare LS50F and blocking filter. I could also investigate what is needed to fit it to my ED80 one day.

Regards
Bill D

[sheeny (Al)]

Originally Posted by TechnoBill

Hmm taking flats the traditional way with the solar scope would be quite hard, as I tend to fine tune the etalon once on the sun to highlight certain features and this moves the hot spot.

No doubt. I suppose if you had a lightbox that could produce enough Ha. Maybe a blue sky shot with long exposure... I've never heard of it being done...

Originally Posted by TechnoBill

As my lunt is a Double stack, I have a spare LS50F and blocking filter. I could also investigate what is needed to fit it to my ED80 one day.

That's exactly what I've done with the SM40. I got the local machine shop to turn up an adapter for me for $50. You might be able to get it for a carton. I have a drawing for the SM40 adapter with dimensions for a neat fit over the ED80 dew shield. I think I posted it here somewhere, but if you're interested I'll dig it up.

Al.