Fred wrote:
Surely the whole point of constant-aperture zooms is that they are
equally fast at both ends of the zoom range, not just at one end?
No, the whole point is that the aperture does not change throughout the
zoom range. I'm not sure but I think a non-constant zoom could be
designed that was of equal (equivalent?) speed at both ends.
I suppose that's true, Mike - for example, a 70-210 zoom could be f/4 at
70mm, and f/4 at 210mm, but could be f/3.5 at 135mm, say. However, that
would certainly be an unusual design, no? (At least, I myself have never
seen anything such as that.)
Not only unusual but probably pretty pointless, too. Just trying to
point out that, when zooms were first available to the general consumer,
the majority of cameras were all manual and constant zoom aperture was
pretty much a necessity.
m
