NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2010 Jun 15, 06:37 -0700
George,
It is my understanding that the modern digital 50mm SLR camera produces an image equivalent to a 75 or 80mm film version. Also the diagonal is probably not a good way to measure with sensors arrayed in a rectangular grid. I stay in the middle of the frame rotating the camera 90 degrees to take advantage of the wide width of the rectangular frame. The Sun (or Moon) and horizon are viewed equally distant from the frame center using the frame center marking in the camera view reticle. No clamping of the camera is needed with shutter speeds over 1/500 of a second. At these shutter speeds camera shake is not a factor and will allow use on a small craft. Sun limbs are surprisingly sharp even with a hand held telephoto. See attached 200mm example. No Sun spots seen in this example nor were any viewed through the 7 x 35 sextant scope. When some Sun spots show up I'll see if they are useful as an exposure tool.
Greg Rudzinski
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