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The first quarter Moon on March 31, 2012. Image made with a telephoto lens on a stationary tripod.
The image was produced with a Canon 1D Mark IV, 16 megapixel digital camera using a 500 mm f/4 L IS super telephoto lens with stacked 2X and 1.4x TCs. The f/ratio of the system was f/11.2. The 1D Mark 4 camera will autofocus at f/8 and stacked TCs which only reports one, so the camera thought the system was at f/8 and autofocus was used for this image. I used mirror lock up with the camera on a tripod. Exposure was 1/125 second at ISO 400. This is a single frame image. The raw data were converted to a 16-bit tiff interpolated to 25 megapixels. During conversion, chromatic aberration and color balance were corrected. The image was then sharpened using Richardson-Lucy image deconvolution using a 5x5 Gaussian and 20 iterations, then a small amount of unsharp mask was applied. The plate scale of the original full resolution image was 0.84 arc-seconds/pixel and the raw-converted image 0.67 arc-seconds/pixel. The diffraction spot diameter for green light is 2.1 arc-seconds (2.5 pixels), or 3.7 pixels in the full resolution image below. The image is diffraction limited. That is pretty good for a telephoto lens with stacked teleconverters. For reference, 1 arc-second is 1/3600 of one degree or about the width of a human hair at a distance of about 50 feet (15.7 meters) (assumed a hair is 0.003 inch in diameter). The full resolution image (1.2 megabytes) can be seen HERE . Note the sharp lunar edge is not perfectly round, but shows the mountains sticking up at the limb.
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Keywords to this image = astrophoto-1 moon canon_1d4
Image ID: moon.1div-1400mm.c03.30.2012.c45i5804.c-s-1024v.jpg
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Last updated September 05, 2024