I think you overestimate the variability of light in a typical nature photography scene. You really don't need to be constantly adjusting the aperature/speed/ISO unless you are dealing with very weird rapidly changing conditions. Even then it is not that hard to hit the green button to take another reading, does not take very long. In fact, by manually focusing and "premetering" as it were, you probably save the camera a few milliseconds that would otherwise be spent on the auto focus/aperture adjustments.
If I were you I would keep this one.
Stan
Peter Alling wrote:
Well I've decided to start collecting money for a purchase of a *ist-D,
(or it's successor if takes too long). So I'm going have to part with some
of my gems and some surplus equipment that I never use. My 300mm M*. I've
been very happy with it but I use it mostly for nature photography and it
wouldn't be fast enough metering with the *ist-D limitations so it's the
first to go. ...
