This phenomenal picture of the sun was taken by astrophotographer Alan Friedman from his backyard in Buffalo, New York, using a Point Grey FireWire camera. The telescope was fitted with a hydrogen-alpha filter, which selected a tiny slice of the visible light spectrum. Hydrogen, the chief component of the sun, radiates strongly in this deep-red light, letting both the sun's outer layers and the feathery filaments that extend away from the disk appear in sharp detail. Instead of just snapping a photo, Friedman took 90 seconds of streaming video and selected only the sharpest frames. Of the 900 frames captured, Friedman threw all but 200 of them away.
In two separate 90-second videos, Friedman zoomed in on the edge of the solar disk to capture wisps of gas arcing along loops of the sun's magnetic field, plus sunspots and the detailed churning of the sun's atmosphere. Then he inverted the solar disk in the image, making all the dark spots light and the light spots dark. This technique, he says, brings out the surface detail in high contrast and provides a smooth transition from the disk to the edge prominences that is closer to what one might experience visually looking through a safely filtered solar telescope.
"It gives a sense of the sun that's both powerful and closer to what you would actually see." In this picture you can see sunspots, giant convection cells, and the gas that follows magnetic loops piercing the sun's surface.
By imaging with a streaming camera, Friedman was able to record brief moments of clarity that come in the midst of otherwise poor imaging conditions. These frames would be virtually impossible to capture using a traditional camera shutter. His imaging technique involves scanning the captured video, selecting (both manually and with software) the sharp frames and then aligning and averaging them to yield a summed image of only the best information from the original data. The Scorpion IEEE 1394 monochrome camera, featuring a Sony 1/1.8" CCD, streams 1600x1200 images at 15 FPS, and offers 20 times the dynamic range of a DMK camera. This range allows the camera to record surface structures in the solar chromosphere, as well as much dimmer prominences at the edge of the sun in the same exposure. The ability to set a Region of Interest (ROI) is another great tool for maximizing the download speed of the camera when the full field is not needed.