Re: "1:" on lens label -- what does it mean?
- From: stephen@xxxxxxxxxxxx (Stephen M. Dunn)
- Date: Sun, 30 Oct 2005 22:13:34 GMT
In article <Hgb9f.5029$UW5.886@trndny09> none <none@xxxxxxxxxxxxxxx> writes:
$On the front of my P/S lens, there is a label that says:
$5.8-32mm 1:2.6-5.5
$
$And on the front of my film SLR lens, the label says:
$35-80mm 1:4-5.6
$
$My question is, what does the "1:" in front of the aperture mean?
It's just a different way of writing f/, expressing it as a ratio
rather than by division.
f/x means the size of the aperture is the focal length divided
by x; in optics, the letter f is used to denote focal length (and
on some lenses, you'll actually see the focal length shown in the
form "f=50mm").
1:x means that the ratio of the aperture to the focal length is
1:x.
--
Stephen M. Dunn <stephen@xxxxxxxxxxxx>
>>>----------------> http://www.stevedunn.ca/ <----------------<<<
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