NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sun CN with DSLR Camera Revisited
From: Marcel Tschudin
Date: 2011 Oct 5, 13:53 +0300
From: Marcel Tschudin
Date: 2011 Oct 5, 13:53 +0300
Greg,
It looks like there is still not so much interest in trying to use a camera for CelNav measurements. Attached you find the results I obtained from your photo. For all the others to those it might eventually also be of interest. I measure the pixel-height slightly different than Greg. Greg crops one picture to have the horizon at one end end and the sun position to be measured on the other. His pixel-height is then the size of the cropped picture. I use a program where I measure the pixel positions in the original photo with an arrow cursor. Generally I take 4 to 6 measurements of the same position and take the difference of the mean values. The attachment shows the measurements of the LL, Centre and UL of the sun. The conversion pixel to MOA has been performed with the two equations shown on Greg's scale-graph and also using the value taken from the graph itself. The atmospheric conditions for Oxnard CA were found on www.wunderground. What does your Palm Pilot show for my measurements? BTW: I would not use the filter as a stripe through the middle thus hiding also the horizon directly below the sun. How about covering only this half of the lens where the sun will be and leaving the other part with the horizon unfiltered?
Marcel
It looks like there is still not so much interest in trying to use a camera for CelNav measurements. Attached you find the results I obtained from your photo. For all the others to those it might eventually also be of interest. I measure the pixel-height slightly different than Greg. Greg crops one picture to have the horizon at one end end and the sun position to be measured on the other. His pixel-height is then the size of the cropped picture. I use a program where I measure the pixel positions in the original photo with an arrow cursor. Generally I take 4 to 6 measurements of the same position and take the difference of the mean values. The attachment shows the measurements of the LL, Centre and UL of the sun. The conversion pixel to MOA has been performed with the two equations shown on Greg's scale-graph and also using the value taken from the graph itself. The atmospheric conditions for Oxnard CA were found on www.wunderground. What does your Palm Pilot show for my measurements? BTW: I would not use the filter as a stripe through the middle thus hiding also the horizon directly below the sun. How about covering only this half of the lens where the sun will be and leaving the other part with the horizon unfiltered?
Marcel
On Wed, Oct 5, 2011 at 1:11 AM, Greg Rudzinski <gregrudzinski@yahoo.com> wrote:
The links below will let NavListers try their luck at editing a raw digital image for Sun sight reduction purposes. Linked: A raw unedited image, MOA/Px graph, and work notes.
Greg Rudzinski
Linked File: http://www.fer3.com/arc/imgx/f1-IMG_2548.jpg
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Linked File: http://www.fer3.com/arc/imgx/IMG_0860.JPG
Linked File: http://www.fer3.com/arc/imgx/f5-Picture-73.png
