[time-nuts] A real world project need for timing accuracy...

[Bob Camp]

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-bounces at febo.com [mailto:time-nuts-bounces at 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.

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