First Attempt at Sun - ED80 and Lunt Solar Wedge

[gnomus]

Title says it all,  This was my first go at the sun.  Shot with an ZWO ASI120MM-S and my new Lunt Solar Wedge.  I tried using the wedge without any filter, but the image seemed very bright.  So these are taken with a Baader moon filter screwed into the nosepiece of the camera.   Even so, the ZWO had to be set to Gain: 20, and just above the minimum shutter speed.  Is this close to the correct technique?  I shot 3000 frames at 8 bits and stacked around 25% of them in AS!2.  I did try shooting a mosaic.  However, there were some areas of capture without any noticeable sunspots and I had no idea what to do about alignment points.  Any tips would be much appreciated.  These were sharpened in Registax and then tweaked (and colourized) in photoshop.  

I ended up with an annoying 'blob' (and what looks like a 'partial blob') in the image train just left and below centre.  Its size suggests that it was not on the camera (it's a little big).  I wonder if it was on the moon filter?

I hope I captured genuine granulation and not just brought out noise.  Any suggestions as regards a way forward would be much appreciated.

I can't decide whether 'just' to view the partial eclipse on 20 March, or if I should have a stab at imaging it.  If the latter, I'm not sure what I could do about getting the whole disk in the frame.  Clearly, there will be no time to construct a mosaic.  I could try attaching my DSLR to the LUNT and taking individual frames - would that work?   

[Johan L]

Very nice!

[Montana]

Superb :) but I think you have a rather large dust bunny on the chip, a good blow should do the trick

Alexandra

[michael.h.f.wilkinson]

Dust bunnies can also be overcome by flats, especially if their contrast is modest, as in this case. Otherwise an excellent shot

[gnomus]

Dust bunnies can also be overcome by flats, especially if their contrast is modest, as in this case. Otherwise an excellent shot

Thanks for this. I use flats when imaging DSOs. But how do I take and subtract the flat when solar imaging? Can you point me towards a tutorial? By the way, I use Firecapture with my ZWO?

[michael.h.f.wilkinson]

I also use firecapture with my ZWO. There are various ways of making flats. In white light I find putting a white plastic bag over the front, cranking up the gain and exposure time sufficiently, taking a load of frames and stacking these as flat in AS!2 or Registax works well.

Cheers

Michael

[gnomus]

Thanks again. I read something about de focussing the image for the flats.

My question related to how one does the subtraction? I presume this must be done for each frame of the video, before it is aligned and stacked?

I think my dust bunny is so large, that it is probably something on one of the filters. I'll give everything a better clean next time.

[michael.h.f.wilkinson]

Before stacking select a flat reference under image calibration in AS!2 (similar option available in RS6) and the stacking software takes care of it. I think the dust is further back along the optical train.

[gnomus]

Thanks. I'll take a look at AS2 in more detail. Do you do bias and darks too?

[Pete Presland]

Excellent start