Colloquial usage does not apply to optical physics. Reading what someone says does not mean it is true. Go do the experiments I suggested, then it is your own knowledge you are going by.
-graywolf Bob Blakely wrote: > Sir graywolf, > > American Heritage Dictionary - Cite This Source ap·er·ture > (ap'?r-ch?r) Pronunciation Key > > n. > > 1. An opening, such as a hole, gap, or slit. > > 2. > > a. A usually adjustable opening in an optical instrument, such > as a camera or telescope, that limits the amount of light > passing through a lens or onto a mirror. > > b. The diameter of such an opening, often expressed as an > f-number. > > c. The diameter of the objective of a telescope. > > So, aperture is often expressed as an f-number. I find this to be > univeraslly true when conversing with other photography. Example: Hey Bob, > "What aperture are you using?" I answer, "Eight, Fred." Fred knows I am > giving giving him Normalized aperture. An f-stop is simply a normalized > aperture - normalized to the focal length. It's the same concept as > normalized pressure. When the sidewall of my tire says "MAXIMUM PRESSURE: 45 > PSI", I don't add about 15 psi to account for atmospheric pressure. We all > know that the pressure given in normalized to atmospheric pressure. > > If you wish to anal about it and still be "technically correct" , I suppose > you could refer to the f-number as thr "specific aperture". At least other > photographers will get some useful information from you when you're asked > for the aperature you're using. > > When someone asks the time, they don't want to know how to make a watch. > Take my word for it. > > ----- Original Message ----- > From: <[EMAIL PROTECTED]> > > >> In a message dated 4/29/2007 7:36:03 A.M. Pacific Daylight Time, >> [EMAIL PROTECTED] writes: >> ----- Original Message ----- >> From: "graywolf" >> Subject: Re: M85mm f2.0 bokeh >> >> >>> Most folks do confuse f-stop with aperture, I sure used to. However, >>> they are not the same thing. So you are mistaken here (I have not looked >>> at the Wikipedia article to see if it is correct or not). >>> >>> I am not going to go through all this again, folks, look in the >>> archives; or better yet, get the formulas and calculate DOF using f-stop >>> and aperture diameter, go out and shot some photos and compare them with >>> your calculations. Then, like me, you will never make that mistake >>> again. >> ========= >> Huh. Haven't been paying much attention to this thread. >> >> But I would presume while the diameter of an aperture opening could be >> set >> the same from lens to lens if one fiddled around, a f stop is dependent >> on the >> focal length of the lens. So a f/8 on a 16mm and a f/8 on a 200mm say, >> would >> actually have a different size of aperture opening if one measured the >> diameter. >> >> Is that what you are talking about? >> >> Thanks. >> >> Marnie aka Doe :-) >> >> >> >> >> ************************************** See what's free at >> http://www.aol.com. >> >> -- >> PDML Pentax-Discuss Mail List >> [email protected] >> http://pdml.net/mailman/listinfo/pdml_pdml.net > > -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
