Dawe's Limit ```Name: Terry H. Status: other Age: 50s Location: N/A Country: N/A Date: 9/15/2003 ``` Question: How do you compute the theoretical resolving limit (in arc seconds) and the faintest stellar magnitude visible for any given aperture, focal length and magnification? (I am using a 6 inch Newtonian reflector with 1400 mm focal length and a 28mm Plossl eyepiece). Replies: What you are referring to is Dawe's limit, which is determined by the following simple formula: R' = K / A where R' is the maximum theoretical resolution in arc seconds K is the empirically determined constant 4.56 A is the clear aperture (unobstructed effective diameter of the object lens or mirror) in inches. You may wish to consult the following source: http://www.observers.org/beginner/glossary.html#star%20diagonal ---Unterman Click here to return to the Astronomy Archives

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