I just posted this question in the previous thread but wanted to add one detail. I have a Canon 7D with a 70-200 f/2.8 II IS lens and am looking to improve my wide angle lens for a trip to the Galapagos Islands in a few weeks. I also have the kit lens that came with the camera (28-135 IS).


I've been trying to decide (like many people I gather from reading other posts) between the EF-S 17-55 IS and the 24-105 f/4 L lens.


How important is the weather sealing since I'll be outside a fair amount but don't plan on taking it out in the rain or anything like that? I plan on upgrading to a full frame camera in a few years but have not immediate plans. That led me to initially consider the 24-105 f/4 lens but am concerned about the f/4 stop and shooting wildlife in the morning.


Thanks for any advice you have. I just started with all of this photography stuff earlier this year and am really enjoying it so far.