Here is my composite image of the 2017 total solar eclipse, from a range of exposures from 1/1000 second to 0.4 second, to retain details in the inner corona while bringing out faint streamers in the outer corona fading off into the sky. The blue sky contains several stars, including first magnitude Regulus at left, a rare sight at any eclipse. The disk of the New Moon illuminated by Earthshine is also faintly visible. As such, the image shows a bit more than the eye saw, as the Earthshine is usually not visible to the eye, as it is overwhelmed by the bright inner corona. However, in other respects I have tried to retain a more “natural” appearance to the merged images, to replicate what the eye did see, both naked eye and through binoculars. I’ve avoided a more garish or overly sharpened image, as interesting and scientificially useful as those can be for revealing the finest structures in the corona. The location was the Teton Valley north of Driggs, Idaho off the West 5000 road on the Wydaho Lane. I shot the images through a 106mm Astro-Physics refractor with a 0.85x Reducer/Flattener for an effective focal ratio of f/5 and focal length of 500mm. The camera was the Canon 6D Mark II, at ISO 100. The telescope was on a polar-aligned equatorial tracking mount. Even so, some manual alignment of images was required, mostly due to the motion of the lunar disk relative to the Sun. This is a composite of 7 images blended with luminosity masks applied using ADP Panel+ Pro extension for Photoshop. Adjustment layers of successively smaller High Pass filters were also added to bring out the coronal structure. I tried both merging images with HDR software (Photomatix Pro 6) and with stacking images as a Smart Object and applying a Mean stack mode. While both methods did produce a good result the HDR image exhibited edge artifacts, as HDRs often do, while the stacked smart object lacked detail in the inner corona, and allowed no control over the relative contribution each exposure made to the image.
Here’s a variation on creating a time-sequence composite of the August 21, 2017 total solar eclipse. In this case, time runs from left to right, from the last filtered partial phases I shot, through unfiltered shots of the rapidly changing last glimmer of sunlight disappearing behind the advancing Moon at “Second Contact,” forming “Baily’s Beads, to totality at centre. ] The sequence continues at right with the Sun emerging from behind the Moon in a rapid sequence at “Third Contact,” followed by two post-totality filtered partials to bookend the total eclipse images. The C3 limb had a beautiful array of pink prominences. The Contact 2 and 3 images were taken in rapid-fire continuous mode and so are only fractions of a second apart in real time. Most are 1/4000th second exposures. The totality image is a blend of 7 exposures, from 1/1600 second to 1/15 second to preserve detail in the corona from inner to middle corona. These were aligned, and merged into a smart object and blended with a Mean combine stack mode. It is not an HDR image. I added a couple of layers of High Pass filtering to sharpen structure in the corona. The partials are 1/2500-second exposures through a Thousand Oaks metal-on-glass solar filter for the yellow colour. All were taken through an Astro-Physics 106mm apochromatic refractor with a 0.85x field flattener/reducer for an effective focal length of 500mm at f/5. The flattener added some flares off the diamond rings. The telescope was on an AP Mach One equatorial mount, aligned and tracking the sky, a rare circumstance for me for any total solar eclipse. The placement of the frames here only roughly matches the actual position and motion of the Sun across the sky during the time around totality. Partials and C2 and C3 images layered into Photoshop and blended into the background totality image with a Lighten blend mode, and masked to reveal just the wanted bits of each arc. The site was north of Driggs, Idaho in the Teton Valley, north of the centreline. Thus the diamond rings are above the centre of the Moon’s disk.
The August 21, 2017 total solar eclipse over the Grand Tetons as seen from the Teton Valley in Idaho, near Driggs. This is from a 700-frame time-lapse and is of second contact just as the diamond ring is ending and the dark shadow of the Moon is approaching from the west at right, darkening the sky at right, and beginning to touch the Sun. The peaks of the Tetons are not yet in the umbral shadow and are still lit by the partially eclipsed Sun. With the Canon 6D and 14mm SP Rokinon lens at f/2.5 for 1/10 second at ISO 100.
