"scott" wrote in message
news:NfHEc.276$WO5.171@newsfe3-gui...
When you see a 200mm lens, what is the 200mm actually a measure of? I
assume it's something to do with how much "zoom" there is, but surely
measuring the angle that is shown by the image would be better? Eg a
wide-angle lens would be a 90 degree field of view but a telephoto one
would
be maybe 5 or 10 degrees.

In another dimension (pardon the pun) perhaps lenses could be referred to by
their angle of view rather than focal length... it's probably a male thing.
Anyway, nowadays everyone is accustomed to the mm scale, even nations so
stubbornly Imperial in their measurements, that a change to a figure in
degrees would be greeted with a reception akin to a sudden change of
currency.

--
Martin Francis http://www.sixbysix.co.uk
"Go not to Usenet for counsel, for it will say both no, and yes, and
no, and yes...."