A Nighttime Solar Eclipse?

When I tried to print our second 26″ by 36″ canvas copy of “Eclipse Over Long Pine Key”, the colors were as shown below. I thought one of the ink cartridges must be empty or the printer had a clogged nozzle or something. I pulled out the roll of canvas, performed a cleaning, and did a nozzle check, all of which went well, so I did a small (5″ by 7″) test print on luster paper. It turned out the same way. It was late so I just shut off the printer and went to bed. The next morning the printer passed all tests and I was able to make the correct print with no problem. I’ve never had that problem before or since. I was intrigued by the picture and kept the small print as a memento.  I have no idea how to duplicate this image.

Nighttime Solar Eclipse?

Often, when people see the original version hanging in our booth at an art festival, many of them think it shows a time-lapse of the phases of the moon.  I assure them that although the moon plays a crucial role, it is not directly visible in the image. Below is an animation showing the three different celestial events involving the moon.  A solar eclipse happens only during the day when the moon is new, while the lunar eclipse only happens on a night with a full moon.  In the animation, both of those are total eclipses, while both versions of our “Eclipse Over Long Pine Key” show only a partial solar eclipse.  The third part of the animation shows a complete lunar cycle with all the phases of the moon.  In this case, unlike the other two events, the edge of the obscured part of the celestial body will always touch both poles.

Moon Animations

To see the Note click here.To hide the Note click here.
While all parts of this animation are drawn to scale as seen from the Earth, the time compression is different for each celestial event.

Making “Eclipse Over Long Pine Key”

Our latest image, Eclipse Over Long Pine Key, of the solar eclipse in August in the Everglades was by far our most complicated yet. While spending hours and hours overcoming challenges in post-processing, I wondered if I was wasting my time – would anybody even be interested in the results and was each of these steps really necessary, or was I just over-thinking a problem again. You be the judge.

Another Brilliant Idea

Although I wrote a blog article with suggestions for taking eclipse photographs with either your smartphone or camera, we had no plans to take any ourselves. Then, about twenty hours before the start of the event, I got another ‘brilliant’ idea – the concept for a multi-Gigapan panorama and time-lapse image of the solar eclipse.

What I pictured were images of the eclipsing sun as it soared barely over the tops of the skyscrapers in downtown Miami. This image would be taken from a balcony somewhere between the tenth and twentieth floor so you could capture an interesting street view in the foreground. Of course, it would be a Gigapan to give plenty of detail (we’ve been influenced and inspired by fellow Miami photographer Robert Holmes), but one panorama would not be enough. Ideally, as you took each of your carefully placed sun shots, you would need to shoot an area of the city directly beneath it so that the constantly changing light intensity and the buildings’ shadows would change in synchrony with the sun. The sun photos would be taken with a camera with about 16-stops of neutral density filter. For ease of execution, it might be better to have a second camera for the Gigapan unit. Each associated Gigapan panorama would need to have enough overlap with its neighbor to be able to stitch them together and go high enough to capture the sun’s position so you could correctly add in the better sun shot later, and give enough headroom for the sun’s path.

Reality Sets In

Some of the challenges of this project were unanticipated and, as you will see, some were self-inflicted.  Although this was our most ambitious project yet and would turn out to be tremendously challenging for the technical support crew (me), Nancy, with her artistic eye, still made the aesthetic decisions. First of all, we don’t do cityscapes.  We had less than a day to get ready for this shoot, and already had a doctor’s appointment for Nancy’s mom scheduled for the morning of the eclipse. We brainstormed and searched Google Earth to make a list of possible sites. Then, after dropping off Nancy’s mom from the doctor the next day, we headed to the Everglades. The pines on the island in the lake at the Long Pine Key Campground were our first choice. We got there around one o’clock, but I was disappointed in the height of the trees, so although the equipment takes over a half an hour to set up (and the eclipse started at around 1:30), we headed to our second choice, Pine Glades Lake, about six miles away. It proved to be completely inadequate for our needs, but the side trip ate up another hour of valuable time. By the time we returned to Long Pine Key, found the ideal location, and set up the Gigapan, the eclipse was already near its peak (around 2:45). This may still be doable, I told myself; for the sun I can just flip a copy of the pictures we get in the second half of the event. I set up the Gigapan to combine all the missed areas in the first panorama, and then took six more Gigapans after that. Since I only packed one tripod, as I operated the Gigapan Nancy had to lie on her back, pull the 100-400mm lens back to 100mm so she could find the sun on the LCD monitor in Live View, zoom out to 400mm, focus, and push the button every five minutes. Shortly after 4 o’clock, after shooting our seven Gigapans and twenty sun shots, we packed up and went home.

The Real Work Begins

Stitching The Panoramas

Photoshop does pretty well putting together smaller panoramas, but bogs down as the number of images grows (for small panoramas, Canon’s PhotoStitch, which came with the camera, does an even better job). Gigapan Stitch, which comes with their motor drives, does pretty well on the larger panos, but I usually use Kolor’s Autopano Giga because it has more choices in projections, better control options, and does better at eliminating ghosting (which happens when things (including even trees and branches) move between shots). I’m still climbing the learning curve, which added to the time needed to stitch together all seven panoramas. I believe there must be a way to combine the stitched panoramas into one large image with Autopano, but I couldn’t find it in time for this project, so had to warp and stitch the individual panoramas together by hand. Unlike my imagined cityscape, the ground location of the camera and the intervening lake make the concerns about the shadows much less significant. Because of that, and the fact that each of the panoramas was larger than strictly required, I was able to cover the field with only two of the seven panoramas, but then added the last panorama – the one with clouds.

And Now For The Hard Parts

First, The Bad News

When I saw the first of the sun photos on my computer screen, I was amazed that one could capture such details as sunspots with a regular camera. And then it occurred to me that this meant I wouldn’t be able to just flip all the sun shots to re-create the shots we missed, and that since we didn’t have the sun camera on a tripod, I would have to find a way to make sure the suns had the right orientation with the horizon if I wanted this image to be anatomically, or should I say astronomically correct. Also, although I expected the sun in the panoramas to be blown out, I thought I’d still be able to use its position to place the new sun. Wrong! The blown out area was much too large to be useful.

Is There An Astronomer In The House?

But how would I determine the proper position and orientation? For position, I used “The Photographer’s Ephemeris” (TPE) app on my phone (cost: $3) to find the azimuth (compass bearing) and altitude (angle of elevation) of the sun from the location of the camera at any time during the eclipse and I had taken the compass bearing and/or the angle of elevation of a few of the features in the image during the shoot. With this information, I mapped out a grid on a separate Photoshop layer, placed a small circle at the location of each sun, and then used the Pen Tool to mark the sun’s whole trajectory.

Plotting the Sun's Track
For the orientation, I checked the web and even Facebook for pictures or information showing the orientation of the sun and moon’s path across it, but could not find the information I needed. By then it was several weeks after the eclipse, but I thought I could just go out and take new photographs of the sun with the camera on a tripod to get its orientation. My first image, at around 9 am, showed a different sunspot pattern than shown during the eclipse. A photograph taken around 1:30 pm showed that same pattern, but the sun had rotated clockwise about 66° in relation to the horizon from the first shot. This mission wasn’t going to be easy.

I opened each sun photo in Photoshop and erased the black background. On new layers, I found the center (which became slightly more challenging as the missing piece became larger), placed a circle on the sun’s edge, and drew horizontal and vertical crosshairs over it. I duplicated all of those construction lines and moved them to represent the moon. I placed all the layers into a group labeled with the time of the shot so it would be easier to combine these images into one Photoshop file. In this master sun file, I started with the shot taken at the peak of the eclipse and rotated that group so that the moon’s center was directly over the sun’s. As I rotated the other suns to align their spots with the first, the moons’ centers formed a horizontal line about half a radius above the sun’s center. Even better, the distance of each moon’s center from that of the peak moon along that line was basically proportional to the time difference between the two. Because of that, I was able to find the moon’s position at any time and replace the sun photographs that I missed.

Part of Master Sun File
Part of Master Sun File

The Sun’s Trajectory

I noticed that the sun’s 66° difference in orientation in relation to the horizon on my two later test shots seemed to match the change in angle of the sun’s trajectory in relation to the horizon during that interval. I’m still not confident that I’ve got my mind wrapped around all of the intricacies of these three moving celestial bodies, so this could be a coincidence, but I decided to run with this notion. After plotting the sun’s trajectory in its separate layer, we decided for aesthetic reasons (call this artistic license) to compensate for the disappointing tree height by compressing that layer downward (which could possibly have been an accurate representation if the declinations of (or the latitudes directly below) the sun and moon had been somewhat less than the 121/2° they were at the time). To do this, I simply made a selection with the Rectangular Marquee Tool, the bottom edge of which was on the horizon and the other three sides were large enough to include the whole trajectory line. Then, using a scale transform, I just lowered the top edge of the selected area to taste.

The Moon’s Path

I was pretty sure that the moon’s path was not parallel to the sun’s but didn’t know how much to tilt it. I heard that the plane of the moon’s orbit differed by 5 degrees from the earth’s, but didn’t know how that related to the problem. In the master sun file, I saw that the each sun had to be tilted from 0 to over 27 degrees with an average of 10°. I chose to rotate everything in the master sun file 8 degrees.

Sun Spacing

After deriving a trajectory for the sun, at first I selected and placed the appropriate photographs at five-minute intervals. When the eclipse started just after local apparent noon (when the sun crossed our meridian of longitude and was at its closest to being directly overhead), it was moving the fastest through its trajectory and the five-minute suns were much further apart than they were at the end of the eclipse three hours and 77 degrees of azimuth later. Nancy wasn’t happy. Instead of equal time, I considered next an equal-azimuth-change approach, but that would have the suns getting further apart at the end of the trajectory instead of the beginning, so Nancy decided on having the suns the same distance apart on the image, the third easiest of the three approaches because of the curved trajectory and requiring use of the Pythagorean Theorem.

Another artistic decision was the sun’s size. After re-creating the missing sun shots for the times dictated by the new spacing strategy, I copied all the necessary sun folders into the finished panorama file. As I started moving them into position, we decided they were not large enough, so I deleted all of them from the panorama file, increased the number of pixels in each direction of the master sun file by 25%, and recopied the appropriate folders into the panorama file. As I moved each sun into position, I rotated it so that the bottom edge of that group was parallel to the tangent (slope) of the trajectory path at that point. One could possibly ‘justify’ these actions by arguing that the same effect could have been achieved by just moving further away from Long Pine Key.

Finally, we decided to end the string of suns as it went behind a cloud rather than continue to the trees. The problem was that the cloud and the sun were in their respective positions at different times, meaning the cloud was not properly backlit as the juxtaposed position of the last sun dictated. It was my younger brother who first pointed out that “flaw”.

Exposure Levels

As I was setting up the first panorama near the peak of the eclipse, I didn’t notice that the sun was almost three f-stops dimmer than normal (or almost one eighth as bright). I think this shows the eye’s and mind’s ability to compensate for different conditions (although it could just show how oblivious I can be to my surroundings when I’m focussed on a challenge). I determined the exposure level of the camera in the usual way. As I took the later panoramas, however, the camera noticed the change in light intensity. I started getting more and more blinkies, and before the fifth panorama, I added our last (3-stop) neutral density filter.

Since the sky of each panorama was blown out in a large area around the sun, I had to restore its color uniformly across the image and then darken the sky around each sun appropriately. To do that I used Photoshop again to find the relative area of each sunHow, and then use that area to determine how much darker its part of the sky should be.

Conclusions

Well, that’s about everything we considered. You’ve got a little over six years to get ready for the next solar eclipse in this country (April 8, 2024), so don’t wait ’til the last minute to prepare (like some people I know). Hopefully, by learning from the tribulations and mistakes of others, you can make your life easier while still making better pictures. Good luck!  And feel free to leave comments (or questions).