This is really a set of three
blog posts.
In the first, I detail my
attempt to record the 2017 Total Solar Eclipse using my camera phone and
telescope with solar filter.
In the second post, I explain what
the 2017 TSE felt like in Gallatin,
Tennessee, starting at 12:03pm, ECT and extending through 2:17pm, with a local
totality duration of 2 minutes and 37 seconds.
In the third, I give a quick
explanation of how I turned my 1200 photographs into a short film of the TSE,
which I will post as soon as it is finished.
***
In this post, I’m going to
discuss just what I did to capture the photographs of the 2017 TSE. I focus on the techniques and the hardware.
Sometime in high school- I
think it might have been around 2003- I was lucky enough to get a telescope for
Christmas. It was and still is a superb
telescope. It is a 6-inch Orion 8944 SkyQuest Dobsonian reflector. That means it’s a 6-inch wide
tube with a very fine parabolic mirror mounted against the back, and the mirror
reflects the image onto a small objective mirror, which subsequently sends the
light of the image through an eyepiece fitted with a compound lens. It is this compound objective lens that
determines the magnification; it is the width of the telescope that determines
the aperture, or the amount of light it can gather; and it is the length of the
telescope (multiplied by 2) that determines the focal length, which determines
the resolution of the final image, or how crisp and precise it looks once you
stick your eye in there. It sits on a
chunky, pressed particleboard base that swivels so you can adjust where it is
pointed. (No, I do not have a motor
drive- one of those fancy, expensive, computerized setups that orients the
telescope automatically... Although I sincerely wish my telescope could be
fitted with one.)
Then, perhaps a year later, I
received a solar filter. I don’t recall
what the occasion was- Christmas, my birthday, or my own money- but I do recall
that the filter alone ran around $250 at the time, and remains one of the best solar
filters that money can buy. It looks like
a perfectly flat, double-sided mirror. I
can fit the solar filter onto the telescope simply by pressing it over the
telescope. You can see it in the photo
above as a grey cylinder fitted over the telescope’s aperture. That’s Sam checking out the eclipse through a
pair of solar glasses.
The telescope is fitted with a
single optical spotting scope with a 2x zoom.
That sounds like a small magnification, and it is, because the spotting
scope has a much wider field of view, Though the view through the spotting
scope is of a low magnification, the point of this instrument is simply to find
the object you wish to observe and then orient the telescope manually, making
little adjustments once you spot the object through the objective lens. At night you can look straight through the
spotting scope. If you are observing the
sun, you can’t, because you will instantly burn a hole through your retina at
the back of your eyeball, resulting in permanent vision loss in that eye. (Imagine what happens when you create a beam
of heat with a magnifying glass in the sun.
Then imagine that happening inside your eye. Then imagine the fascinating sound you’d make.) So while orienting the scope to the sun, I
just placed my hand 2 or 3 feet behind the spotting scope, and adjusted the
telescope so that the sun’s image appeared in the crosshairs. In order for this to work, I had to calibrate
the spotting scope the day before in broad daylight. To do this, I just pointed the telescope to
the very top branches of a distant tree- because it is easy to find through the
objective lens- and compared that image to the one in the spotting scope. I made adjustments as necessary so that the
two images matched as perfectly as I could manage. Now the spotting scope was precisely oriented
with the telescope’s field of view. In
the shot below you can see how the sun’s image projected onto my hand. The sun’s image looks a little like Pac Man in
this shot because the moon has begun to occlude the light on one side.
So once I had made these
preparations to the telescope itself, I drove with my friends Sam and Mike to
Gallatin, Tennessee, near where the duration of totality was greatest for our
region: 2 minutes and 37 seconds. We
were staying in Nashville, but the duration there was only 1 minute and 30
seconds. So we chose to brave the heavy
traffic in order to chase those extra 67 seconds of totality. We are grateful that we did.
After parking our two cars,
lugging out the telescope, its base, our supply of snacks and water- the heat
was equatorial- we marched down to a sunny spot just on the northern edge of the
Cumberland River. The sky was dotted
with fat, drifting cumulus clouds, just enough to give us some trouble if we
were unlucky. Thankfully, not a single
cloud obscured the sun from start to finish.
I knew that I would be able to
observe the TSE through my telescope, and that it would be phenomenal. What I did not know was whether any of our 3
sets of digital cameras would be able to capture it through the objective
lens. Sticking a camera up to a
telescope lens and snapping away is a notoriously finicky operation, because of
the optics involved. If I had really prepared, I would have bought a
camera adapter and fixed a digital camera to the telescope itself. Alas, the best laid schemes of mice and men.
Michael and Sam had each
brought their own digital cameras.
Mike’s even had manual settings, which is ideal if I was to try
controlling exposure time and f-stop.
But neither Sam nor Mike seemed to be able to line up the optics of
their cameras with those of my telescope’s objective lens. Anticipating failure, I stuck my camera phone
up to the lens as a last resort and began to experiment. I have an LG K20 V smart phone (model number
VS501) with a resolution of 13 megapixels.
Improbably, the camera was able to autofocus on the objective mirror surface, meaning that my photographs were crisp and crystal clear. My phone has an exposure feature that lets you tap a region of the image, and the phone adjusts the exposure and aperture for the brightness. That was helpful near totality, when the exposure time became an issue. I was even able to capture not only high-resolution sunspots, but even the mountains on the edges of the moon. They appear as gentle bumps or hills, not as jagged as I imagined. See if you can spot them here.
Lining up the phone’s camera
with the objective lens was a challenge.
If I didn’t position it manually in exactly
the right location and angle, aberrations blurred the resolution and glare
obscured the edges of the sun and moon.
I was very liberal with my shooting: in the 175 minutes of the eclipse,
I snapped about 1200 photographs, many of them in clusters of 5 or 10 at a
time. This ensured that as the camera
focused and adjusted the exposure, I was almost guaranteed to snap at least a
single decent shot for that cluster. All
the images produced for the video are the highest quality I was able to fish
out of my total gallery pool.
Immediately before, during, and
after the totality of the TSE, I stopped shooting through the telescope
objective lens, because the light meter was having trouble trying to figure out
what I was doing. It would over-expose
while also letting in too much light with a wide aperture, so the slender image
of the sun’s remaining sliver shone much too bright.
Of course, in those moments
before totality, I really just needed to soak up the experience of the eclipse, and I attempt to describe it in my next
post, which will soon be posted at this link: 2017 Total Solar Eclipse: The Experience. Here's a video I started shooting about halfway through totality.
After totality, the hundreds of
eclipse-seekers quickly disbanded, and we were more or less left alone. Sam and Mike could have left, but I really
wanted to capture the remainder of the eclipse so I could document the full approach
and recession of the moon from the sun’s disc.
My friends appreciated this and stuck around in spite of the oppressive
heat. (At least they had the option to
relax in the shade while I became soaked in sweat in the amplifying sunlight
and heat. You can’t shoot an eclipse
from the shade.)
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