Our Sun is something that we take for granted and while there are many like it, this one is ours. It is a fiery ball of plasma surrounded and pierced by magnetic fields, technically classified as a yellow dwarf or more precisely a G2V. It is this sun that has defined who we are through evolution, helping biology to craft our eyes, our skin and even the chemistry of DNA and the mechanisms of its repair. Arguably, it is the sun that has defined biology itself on planet Earth. Its a discussion for another time but you can get some of it from a visual perspective if you ever manage to catch Robert Marc’s color lecture.
This top, introductory image (click on it for the full resolution image) is a test run for an upcoming annular eclipse on May 20th. I made the image in my backyard on Saturday and was not sure if it would come out. In fact, I was not sure that the spots I was seeing were truly sunspots until I checked with NASA’s sunspot page (below) and saw the precise sunspots seen in my imagery. Pretty exciting stuff… Note that the large sunspot in the image is larger than the planet Earth. If you also look carefully, you can see some of the fainter features on the image above as well.
There are a number of ways to examine the sun including using NASA’s real time update page that shows in near real time, a variety of methodologies here. But if you want your own photos there are a number of ways to get them, some of them generating truly spectacular imagery. You can purchase special telescopes dedicated to solar observations, but for the eclipse on May 20th, I am less concerned about the detail on the surface of the sun and photographing through one of those special telescopes is something that would require additional expense (telescope, mounting gear for camera, etc…). I want to show the moon and the eclipsed sun in the upcoming photographs.
My approach to photographing the sun is much simpler and much less expensive, but first let me first say this: Believe what you were told in kindergarten about looking at the sun. Looking at the sun is dangerous and not good for your eyes, particularly your retinas, so *never, ever* look directly at the sun. The approach below will ensure that your eyes never appear in the optical path unless you are stupid enough to look through the objective at the sun with your own eyes.
The approach used here is one that has been used in the digiscoping community for some time. Essentially, it uses a spotting scope, in my case a Zeiss 65mm spotting scope hooked up to an inexpensive point and shoot camera. There is a picture on my setup here. I’ve been using an old Canon SD800 IS, but have been thinking of upgrading to a small point and shoot that can shoot RAW as the dynamic range from the old jpg images on the SD800 is frustratingly narrow. Of course hooking up a camera to a spotting scope and pointing it in the direction of the sun will get you a retina or a CCD searing solution so the important part is using filters to cut down on the amount of light. I’ve been using stacked B+W ND 3 filters, each capable of a 3 log unit reduction of light coming through the lens.
After putting the stacked filters on the scope, I position the scope and focus exclusively through the LCD viewfinder on the back of the camera. This ensures that I never place my own retina into the optical path
You can get a sense of how dark these filters are from this image looking through the ND 3.0 filter (good for 10 stops), held up against my monitor. A single filter was not quite enough for me to reliably see the sunspots in exposures. So, I stacked them which allowed for more control over the exposure on a camera that gives you limited manual control. Some of the newer point and shoot cameras that allow full manual control may be different, but there is still some concern about heat and flux, so I felt better knowing that I had knocked 6 log units off of the flux through to the CCD chip.
This solution should enable you to get decent images of the sun and sunspots using low cost materials and keep your eyes out of the optical path provided that you use the LCD screen on the camera as a composition and viewing tool. Note: I am not sure about thermal effects of sunlight on the CCD. I did not leave the image on the camera CCD for long out of fear that I’d overheat or damage the sensor on the camera, but it was certainly long enough for me to compose and capture the images. I tested the camera afterwards and no apparent damage occurred, though your milage may vary…
The title of this post was taken from William Blake in his 1793 illuminated book, America: a Prophecy. ”Fiery the angels rose, and as they rose deep thunder roll’d. Around their shores: indignant burning with the fires of Orc.”
I don’t know why this quote was rolling around in the back of my head as I was making this image of our Sun, but every time I see imagery of the sun, this quote surfaces in the back of my mind.