This was my first eclipse where I really wanted to try processing out a nice image. I'll begin by saying that the pieces are falling into place, but a serious error compromised my efforts. More on that later.

Our little expedition of friends located ourselves in Goldthwaite, TX. Slightly off the centerline, and a bit North and West of our intended location, Lampasas. We had been watching the weather closely, and it really seemed like overall trends would favor heading to the West and North to escape the surge of moisture out of the Gulf of Mexico. Figuring 3m29s of totality was better than 4m20s of clouds we settled in Goldthwaite, a small community with a nice municipal park where a few hundred people  were gathered.

This image represents a stack of 10 images taken with my Canon 7D Mark II camera set at ISO 100 and a Canon 100-400 mm telephoto at 135mm and f/8. With the crop sensor, 135mm would be similar to ~200mm with a full-frame sensor.  I used an iOptron Sky Guider Pro mounted on a Manfrotto 055MF3 tripod. The camera sequencing was run Robert Haley's excellent freeware package for Canon cameras, CaptureEclipse The images obtained from a cloudless segment of the eclipse included:

1. Exposure 1/800 sec
2. Exposure 1/200 sec
3. Exposure 1/100 sec
4. Exposure 1/50 sec
5. Exposure 1/25 sec
6. Exposure 1/13 sec
7. Exposure 1/6 sec
8. Exposure 1/5 sec
9. Exposure 1/2 sec
10. Exposure 1.3 sec

I should begin by saying that while I would consider myself an intermediate user of Pixinsight, I am a completely fumble-fingered user of Adobe Photoshop Elements. I did add on the Elements+ package which added some scripts to streamline a few things, but I am worse than a beginner right now.

Processing Notes

After an initial crop in Pixinsight, I applied a gentle LarsonSekenina filter in Pixinsight. This filter was developed by Steve Larson (UA) and Zdenek Sekanina (JPL) in 1984 to help bring out rotational and translation changes in comets.  (https://articles.adsabs.harvard.edu/pdf/1984AJ.....89..571L) I used 0.0 radial increment and a angular increment of 0.5. X and Y centered on the sun's disk. I used a small amount setting: 0.3 to the luminance image.

Next, I stacked up up images 2-10 in Photoshop Elements, with opacities as follows:

1. 10%
2. 12%
3. 20%
4. 27%
5. 30%
6. 35%
7. 40%
8. 49%
9. 70%

I started by carefully checking the registration of images and making adjustments so they lined up. I then flattened all of the images into  a TIFF file.

I followed this up with a series of small adjustments using Generalized Hyperbolic Stretch in PI. I had to be careful with this, as I think the stacking algorithm in Photoshop Elements leaves a isophotoal banding that pops out with too much stretching. I also used linear mode to bring up the black point a bit. I'm sure that there is probably a diffusion filter of some sort between layers that can tame the banding in the flattened image.

I then applied a unsharp mask, followed by a couple of gentle applications of Noise Xterminator.

Back in Photoshop Elements, I upped the blue channel a bit, which I think gives the image a bit more of a pearly look that the corona definitely has.

Finally, I layered in one more image (Exposure 1 above) which has little corona but captured the prominences and their nice H-Alpha glow. I first sharpened the image a bit using an unsharp mask then and then layered it in with a 10% opacity.

My screw-up

I had set my rig up 4 times before to make sure I had a good sense of how it came together, to make sure that my batteries in the laptop and camera could run the whole duration and that I could home in on the proper focal length setting. That was going to be ~350mm. 

To set up, I first set the lens at 135mm to help me find and center the sun using live view on the camera. I was so happy that I had managed to get it centered nicely and focused, that I forgot to change the lens focal length! Argggh! The solar image is only about 300 pixels across, so I clearly lost a good opportunity and that explains some of the jaggies along the limb.

Checklists. Also next time I will look into a simple centering tool that might allow me to easily find the Sun at a higher focal length.

Thoughts 

When we arrived in Goldthwaite, skies were looking promising, but a high, thin cirrus was apparent. We were just happy that we might see anything. I did obtain a series of partial images on the sunup to totality with no problems. Just as totality approached, a rapidly-moving cloud band rolled in a wiped out the first half of the eclipse. Fortunately, those moved on and I managed to get a full sequence with no obscuration. Also caught Bailey's Beads and the Diamond Ring at the end. Still, it would have been nice to have several sequences for HDR stacking to help reduce the noise and provide more definition of the coronal streamers.

Most of the guides to eclipse processing presume a full version of Photoshop, and I really chafe at the subscription price for that. I suppose when I consider what I spend on this hobby, I should relax. Still, I'm pretty convinced I can do this all in PI, and I have a goal to try and replicate the Photoshop side with it.

While this was not my first eclipse, the prospects for recording another had us planning to travel again. The 2027 opportunity for a 6m+ eclipse has us excited, and we are planning a trip to Egypt for that, although it will be HOT. Prospects for clear weather are excellent, however.

I am looking into upgrading my camera to an R5. That will give me a full frame, lots of pixels and should create a nicely framed image with my Televue Pronto, which has been to three eclipses so far.

I have the bug!

Any constructive criticism or directions where I might improved the stacking or other processing steps would be welcomed.