On Fri, 06 Sep 2002 15:41:09 +0900 chandler@yomogi.or.jp (chandler) wrote: > [?]zzet <izzet@vizo.com> writes: > (The first character is only an "i". However in Turkish alphabet we have two i's. One WITH the dot on BOTH the uppercase and the lowercase, one WITHOUT the dot on BOTH the uppercase and the lowercase. They are pronounced differently, of course). Now about the focal length: The point is the "original writer" should know what he is talking about. He is the guy who reviews (and most probably owns the website) digital cameras in dpreview.com. What's more, he used to use "equivalent focal length" now he is quoting "focal length", and giving the same numbers. And this behaviour is not peculiar to him. I can understand layman mixing apples and pears, but when serious people adopt to this behaviour..??? > (The first character of your name appears on my monitor > as Japanese > phonetic 'so'. I'm sure that isn't right, but I don't > know what it's > meant to be.) > > > Hi all, > > > > We all know that focal lengths of digital cameras are > given as 35 mm. > > equivalent focal length due to small size of the ccds. > I have seen in > > lots of places, that this is explained as "this is the > focal length that > > gives the same magnification as a 35 mm. camera". > > > > I may be missing something but I think that the only > equivalency is in > > relation to the field of view, not magnification. > > I think you understand it right, basically, despite the > efforts of the > dumbing-down crowd to confuse you. > > The focal length of a lens is the distance from optical > centre (rear > node, I think) to an image formed of an object (subject) > at infinity. > End of definition. The problem is that people use the > focal length of a > lens for 35mm format to specify the angle of view, and > perhaps the > original writer thought that "magnification" was another > way of saying > "angle of view". > > The term "magnification" usually means the (physical) > image size divided > by the object size. Unfortunately, they then for example > use "macro" to > mean 1:1 or bigger in a particular format, typically > 35mm; this isn't > really very sensible, because the effective 'degree of > closeupness' of > an image is really the size of the subject. So if you > have a butterfly > with a 2cm wingspan, and photograph it frame-filling with > large format, > 35mm, and a typical CCD camera, the optical magnification > is wildly > different, but the 'degree of closeupness' is the same. > > HTH > This message brought to you at 8 bits per character, > spaced 4 light > years, 3 ells, and a carrot apart. > > Brian Chandler > ---------------- > geo://Sano.Japan.Planet_3 > http://imaginatorium.org/ >
