Bob said: If you were going to do precision optical work at these distances, you would do it over a cool surface at night rather than a hot surface.
And in the winter during nights with very low humidity and not a trace of wind. Or you would pay the truly humongous bucks for an optical perturbation analyzer/canceller, aka an adaptive tip-tilt corrector (cf. Keck telescopes) And two semis to haul it and a team to set it up and calibrate it.... On Tue, Nov 2, 2010 at 11:26 AM, Bob Camp <li...@rtty.us> wrote: > Hi > > The issue is that you are trying to view over a heated surface (close to > the > ground in sunlight). The distortion induced by the "thermals" is enormous. > The the target "as viewed" does indeed move around. In the absence of > atmosphere and it's issues, the problem would be much easier in a number of > ways. > > If you were going to do precision optical work at these distances, you > would > do it over a cool surface at night rather than a hot surface. > > Bob > > -----Original Message----- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of jimlux > Sent: Tuesday, November 02, 2010 9:28 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] A real world project need for timing accuracy... > > 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.