Hi Guys,
some very interesting comments and observatgions.
@naskies(Dave) - some extremely insightful information there Dave. Thanks so much, and the website you make use of seems incredibly useful in helping to assess the various lenses. I didn't even know it existed before now. Very informative, - thanks a million.
@AndyK - good point. Even with my limited knowledge, I was thinking there'd have to be a very good reason to replace a 400 max zoom with a 300 max. But as you explain, it's an as-well-as, not a replacement. I like the idea of the improvements mentioned though.
@Troy - is the autofocus slower to the point of being a nuisance? And to answer your last question, the only lenses I have at all are the ones that came with the camera, - ie the 18-55mm and the 75-300mm, both of which are possibly not fantastic quality, nor fast AF.
Thanks again guys. I'm really enjoying the amount of information that's coming out of this thread