Message posted by gary on November 18, 2002 at 18:02:41 PST:

A good equation to keep in mind is s=r*theta, where s is an arc length, r is the radius, and theta is the angle in radians. If you have a 50mm lens used on a 35mm format, the field of view in the hortizontal axis is about 40 degrees. If you had 40 of these puffs in a frame, that would be about a degree per puffs. Since you need seperation between the puffs, figure each puff is 0.5 degrees wide. Converting to radians and using 50ft in width for the puff, you would need to be about 2900ft away, or a bit more than half a mile, to see the puffs.

In Reply to: Observablility threshhold... posted by Scott on November 18, 2002 at 12:29:52 PST:

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