Hi The Wikipedia numbers would all work out just fine in a vacuum or in *very* still air. I have yet to find a real world situation (daylight) where you are anywhere near those conditions.
Bob On Nov 2, 2010, at 1:16 PM, Robert Darlington wrote: > Hi Jim, > > This doesnt' look right to me. I'm getting roughly 2.3 inches at 2400 feet > is 0.08 miliradians. 0.01 miliradians (1*10^-5 radians) at 2400 feet is > 0.288 inches (roughly 30 caliber). Wikipedia says that to resolve 0.01 > miliradians you need: > > R (in radians) = lambda / diameter (of scope) (aka, Dawes Limit if you use > 562nm light) > > 1 * 10^-5 radians = 562nm (green) / X > > X= 5.62cm aperture or 2.2". This is what it comes to on paper, in > practice you'd probably need something bigger because of atmospheric > effects, lens quality, and the like. > > That being said, I can't see my holes at 300 yards with my Leupold scope > with an opening greater than an inch. I can just barely make them out at > 200 yards. See http://en.wikipedia.org/wiki/Angular_resolution - Also, > somebody please double check my math. > > -Bob > > On Tue, Nov 2, 2010 at 7:28 AM, jimlux <jim...@earthlink.net> wrote: > >> Bob Camp wrote: >> >>> Hi >>> >>> Ok, I mis-understood the question. >>> >>> In my experience, you can have big buck (as in many thousands of dollars) >>> optics and not see .2" holes at 800 yards. The bull's eye is a *lot* bigger >>> than the hole the bullet made. >>> >>> 0.2" at 2400 ft is about 0.08 milliradian.. or 0.3 minutes of arc. Your >> eye can resolve about 1 minute of arc... I'm not questioning your >> experience, but it seem that even a moderate power scope should allow you to >> see the holes. As I recall, the Rayleigh limit for resolution is something >> like 0.7 milliradian/mm of aperture, so 10-15 mm aperture would be in the >> right ballpark.. >> >> I can imagine needing more aperture than 3", though.. you're not interested >> in resolving a star, but something more akin to separating dots. >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.