Purchasing 7D - please help with lenses!!!!

[neuroanatomist]

Maybe the 18-135 kit would be a good start, and when you have learned what you're missing with that lens the answer to your questions may be answered "automatically". E.g. when you have built a library of lots of photos you can easily see what focal lengths you prefer.

That's a great point. For example, with my 24-105mm lens, the distribution of shots by focal length looks like this:



From that one could conclude that I need both a wider and a longer lens, and perhaps that if I was looking to add a prime, I should be looking in the 24-60mm range rather than at the top end. Of course, for me such an analysis is confounded by the fact that I already have several prime lenses within that range or as well as zooms that overlap portions of it.

Other zoom lenses show a similar pattern for me, similar weighting toward the two extreme ends of the zoom range, and a spread through the intermediate focal lengths, with the combined frequency at the two ends exceeding the balance of the shots. One exception is the 100-400mm, with the vast majority (80%) of shots at 400mm (so...perhaps I need a longer lens...but then again, only 10% of my pictures are shot with the 100-400mm...).

OTOH, the OP is visiting some interesting places in the near future, and IMO it's probably better to take lenses that will give the best IQ possible. The 18-135mm is a decent lens, but not at its best until it's stopped down beyond it's already-slow wide open apertures, and that best is short of other lens' wide-open performance. If, later on, it semes other focal lengths would be better suited, the lens(es) can be sold - and the lenses we're discussing (17-55mm, 10-22mm, 70-200 L's) hold their value very well. Notably, the 18-135mm does not have a high resale value (nor do any kit lenses, since the market is set by the discounted kit price, not the lens-only price - and that applies to the 24-105mm f/4L IS as well - the best time to buy a new one is with a 5DII!).