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The Great American Total Eclipse, 


            Gilbert Ikezaki

The Great American Total Eclipse

Technical card

Resolution: 4759x2677

Date:Aug. 21, 2017

Frames: 3

Focal length: 600

Data source: Traveller


This is the way I saw it. Here is why: Layering different exposures to increase the apparent dynamic range of an image is the key to how most current astronomical pictures get their distinctive look. This high dynamic range (HDR) processing technique increases the local contrast to allow media that does not inherently have a wide dynamic range to show details similar to what we see with our own eyes. The dynamic range of glossy white paper with indoor lighting is on the order of 8 stops (doublings of light intensity, aka powers of 2). A good monitor in practice shows about the same because the most common file type used for image distribution is JPEG which only uses 8 bits per color. 8 bits is 2^8 levels of brightness, meaning it is the same as 8 stops. Depending on the situation and the person, the "naked eye" sees as much as 12 stops or more. Sight is person dependent because there is a wide variation in our genetics. For example, most people see in 3 colors because they have cones with 3 colors of pigments. Color blind people see in bicolor because they have only 2 colors of pigments. A very small minority of people see in 4 colors because they have cones with 4 colors of pigments. However, the eye itself doesn't see anything. It is the mind using the brain that sees things. The brain uses many processing algorithms to let you "see" things. Some of the firmware algorithms built into most people's brains are similar to HDR. It bugs me when someone says they want a "natural photograph" with minimal processing. The fact is that HDR post processing of a camera image is actually closer to what you experience in real life. The "rays" in the corona are created by different densities of gases streaming along the magnetic field lines of the sun. When I saw the eclipse, I saw hints of those rays even without binoculars. While this image is "fake" in that it does not have the same true brightness range as the real thing, The level of detail is true to my eyes at least. It is this detail seen with the dynamic range of the eye that makes seeing a total eclipse in person so special.

Exposure for 600mm f/8:
+0: 1/60s @ ISO200
-2: 1/125s @ ISO100
+2: 1/60s @ ISO800

Location: Brigham Young University, Rexburg, Idaho, USA.



Gilbert Ikezaki
License: Attribution-NonCommercial-ShareAlike Creative Commons


The Great American Total Eclipse, 


            Gilbert Ikezaki