Sun 26-8-2012 Ha

[GlassWalker 99]

My first full pano of the sun. Actually, it was a 99% pano as I missed a tiny bit of the edge with all the processed frames, but the content aware fill in Photoshop did a great job. Since it didn't have any real detail in it anyway, I didn't go back to the raw files to expand the processing region right to the edge to recover that.

This is also my first time using flats for solar imaging. Why didn't I do this earlier? I only tried it this time as there were rather a lot of dust spots I couldn't clean. In order to make a flat, I did the deep sky trick of putting something over the objective. Unfortunately that killed the sensitivity, so I had to jack up to 2 second exposures and maximum gain to see anything at all. Leaving it running for some minutes I got 200 frames and that stacked into a nice dark frame. Well, almost. I was now getting hot pixels too. My fix for that was using the dust and scratches filter to remove them, tuned so as not to remove the actual dust spots which I wanted to keep! The flats also got rid of the stripe optical interference pattern I got at times.

Overall, this does give more detail than a single shot full disc capture. But it's not half a lot more work! I used 11 frames in order to fit it. Kit: PST with Hyperion eyepiece projection into DMK41. No idea what image scale is, but about 3 frames will get me across the sun with overlap.

[Montana 1,672]

WOW this was worth every bit of time spent, it is a real gem well done

Alexandra

[JamesF 13,669]

Very nice indeed. Ha solar images look so good.

James

[DrRobin 3,484]

Hi,

How are you doing the flats?, just putting a t-shirt over the front lens, point at the sun and de-focussing? I have a flat light box, which works great on my main scope and DSLR, but I don't know how well it would work on a PST.

[GlassWalker 99]

I used a white carrier bag elastic banded to the front. I had to point at that sun to get any signal at all, with the camera gain set to max and a 2 second exposure. No defocus.

For fun, here's the flat stretched to show the variations:

I never noticed so much dirt on the sensor, but thankfully only the really big ones with a clear ring around them were really noticeable. The diagonal stripes are back and now neutralised. Also I never noticed the vertical banding before either.

[DrRobin 3,484]

Hey, that is great thanks for the tip. Interesting as the frame is fairly even, not too much darkening towards the edges.

It is amazing how much dust you can get even when with the eye or magnifying lens it looks clear. I find that I have to clean, check and repeat several times to get rid of all the dust on the camera.