I believe there is a difference between lens flare and coma. Lens flare is caused by internal reflections in the optics, while coma is an artifact of spherical aberration. The errors on the outer portions of a camera image are not always coma, but may be caused by other abberations as well. I agree, the flare Jim recorded is not an artifact of the optics. I believe he caught some of the initial failures of the orbiter. As I mentioned before, the time line indicates the problems began before we saw Columbia, and continued while it was overhead our location. Brent --- Patrick Wiggins <paw@trilobyte.net> wrote:
Hi,
first, a minor correction. I started at f/1.2 and the change you saw me make was to f/2.0.
The flaring I was referring to might more properly be referred to as coma, something that occurs mostly (you experts out there correct me if necessary) around the edges of the field. In astrophotos this makes the stars on the edge look like little comets. I made the change in f/stop since I thought I might pick out a star or two near the edge.
I don't think the stuff you are seeing on your pictures is caused by coma.
Patrick
Jim Gibson wrote:
I watched you as you set up your camera at Leeds
prior to the Columbia
fly-over. You first set the f-stop dile to f2.8. Then you audibly made the remark something like "I will go up one stop to reduce flairing". Subsequently you set f-stop up one notch.
I set my camera to f2.8 and I don't know what Marty's was set at that you posted at http://planet.state.ut.us . When I blow my picture up of the flair-out I see a bright light start from the left side of the contrail, immideatly cross over to the right side and continue there in a stright line for a bit then blend back into the main contrail. My question is do you think that this was an artifact of my f2.8 f-stop that you avoided?/
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