On Thu, 1 Oct 1998 08:42:30 +1200, "Geoff Bryant" wrote:

[...]
>Of course, at f4.5-5.6 it's pretty slow, though for the kind of work you're
>likely to use it for that doesn't matter too much. There are times I think
>about switching to a faster lens for a brighter viewfinder image and
>slightly easier focusing, but the great versatility of the zoom always wins
>out - at least so far.
[...]

Actually, it is faster than one would think at first...
A standard-design f2.8 macro at 1:1 is effectively f5.6
wide open - the 70-180, though f5.6 at infinity at 180mm,
remains effectively f5.6 regardless of focus, so near 1:1
it is still about f5.6 wide open... There are very few
macro lenses that break by much the f5.6 maximum effective
aperture at 1:1, though at less magnification, they would
be somewhat faster. Since most of the recent designs use
zooming for providing part of their close-focus ability,
their effective aperture does change less with focus.