Who goes wide with an extender on? Please note: Just a bunch of speculation based on no personal experience follows! I wouldn't buy the combination until we've at least seen the mechanics (not to mention the results) of it, but I'm guessing you might be able to take off the extender when you need the wide end again (or, ideally, you only put on the extender when you anticipate you'll need to go beyond 300mm; sacrificing aperture all the time seems distasteful). It's not as seamless a solution as the 28-300mm itself, but you still are keeping it down to essentially one lens in your kit.
That all depends if I'm working on the right assumptions. The big question for me, which I hope somebody can fill me in on, is how the lens operates. My experience is mainly with primes where the focusing is internal near the back of the lens - getting closer as you focus to infinity, farther when you focus closely. The 28-300mm is a push-pull design so I would assume that changing the focal length from tele to wide may not move the groups near the back of the lens much closer to the film plane. Is this on the mark or off? Only zooms I've got sitting around are some super cheap ones with rotating front elements - and the front element goes farther out at wide AND tele, coming in a bit for the middle of the range. (Examples are the Nikon D3000 kit lens and the EF 28-90mm III for the Rebel 2000 film SLR).
For the speed - I think this combination would make an excellent "travel lens" for landscapes and architecture. Even without an extender, the f/5.6 aperture doesn't seem fast enough for action, though I would be tempted to try it for bird photos.
Log in Register
Your B&H Photo login also works for B&H Insights! After your first login you will be able to create a username.