Deviation Actions

Full Moon at f-11 on 20051215



Some more experimentation with obtaining improved pictures of the Full Moon in Northern California on 20051215.

The Moon was higher in the night sky, which meant less air to look through. I wanted try slower film speed for better digital noise performance as well, so this was ISO 400 instead of ISO 1600. The gear used was a Canon EOS 20D camera, with a Canon 70-200mm f/2.8L ISM superzoom, with a Canon Extender EF 2x II providing 2x teleconversion for measured focal length of 385mm, and costs 2 stops of light loss. One goal was finding the sweetspot in the optics before diffraction limiting caused softness. This is generally 2 stops slower the wide open, but I was unsure of what that would be with the teleconverter added to the system. Due to the 1.6x cropping factor of the EOS 20D camera, the actual focal length though is 616 mm, which makes this a kind of Newtonian telescope in effect. I had meant to shoot at the full 400mm (e.g. 620 mm focal length, but looking nearly straight up at the night sky, the superzoom lens probably sagged a bit. This shot was done at f/11, with post-processing using the GNU Image Manipulation Program (GIMP). There is very little histogram in a Moon photo. However, using curves in The GIMP to move the 25% gray point to the 50% point, where the curve bows DOWNWARD creates just absolutely sparkling detail in the gray levels! Two last pieces of "special sauce": (1) on the Canon EOS 20D, one can render black-and-white in camera ... this greatly improves the signal-to-noise ratio, because three colors R, G, and B in the Bayer patter on the CMOS sensor all contribute to the gray tone output; (2) selecting an orange digital filter option appears to offer the best contrast enhancement for the Moon. Finally: this was a hand-held shot!
Image details
Image size
1512x885px 384.28 KB
Canon EOS 20D
Shutter Speed
1/250 second
Focal Length
400 mm
ISO Speed
Date Taken
Dec 15, 2005, 11:05:56 PM
© 2005 - 2023 mabaxter
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printsILike's avatar
Great picture, and the detail about capture & post-orocessing is excellent, thanks for taking the time to explain the shot!