Dawes' limit
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Image:Airydisks dawes sqrt.png
Dawes' limit is a formula to express the maximum resolving power of a microscope or telescope. It is so named after its discoverer, William Rutter Dawes
,Dawes, W.R., Catalogue of Micrometrical Measurements of Double Stars.
In: Memoirs of the Royal Astronomical Society, Vol. 35, p.137 1867, {{bibcode|1867MmRAS..35..137D}} although it is also credited to Lord Rayleigh.
The formula takes different forms depending on the units.
| |R = 4.56/D | D in inches, R in arcseconds |
| |R = 116/D | D in millimeters, R in arcseconds |
| |where | D is the diameter of the main lens (aperture) |
| | | R is the resolving power of the instrument |
This formula agrees with the usual
at a wavelength of about 460nm, somewhat bluer than the peak sensitivity of rod cells at c. 498nm.
See also
References
{{Reflist|refs=
{{cite news
| url = https://www.skyandtelescope.com/observing/pushing-limits-a-spring-sky-double-star-romp/
| title = Pushing Limits: A Spring Sky Double Star Romp
| work = Sky and Telescope magazine
| author = Bob King
| date = 2017-03-01
| archiveurl =
| archivedate =
| accessdate = 2020-02-12
| quote = The most stringent test of telescopic resolution uses the criteria of Dawes' limit given by the equation R = 4.56/D, where R is the resolution in arcseconds and D is the telescope's aperture in inches.
}}
}}
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