« on: October 30, 2014, 08:18:44 AM »
I had the 17-55 IS. I have used it in dusty (Antelope canyon) and rainy (Oregon) conditions without any problem. I always kept a filter on, and zoomed slowly if I was worried about dust. I never had any dust inside my lens (not that it affects IQ anyway).Werz,
The 16-35 is weather sealed, of course, but if you are careful enough then I would weigh that sole advantage over the several that the 17-55 offers:
1. Two to three stops of image stabilization.
2. Less than half the price
3. Fully usable (sharpness, vignetting, etc.) wide open and quite acceptable corners
4. Much lighter and slightly smaller
5. The 35-55mm focal range, which makes it a very good portrait lens (and the bokeh is quite nice)
If you take the 16-35mm f4L IS you'll be happy. It's a fantastic lens, fast AF, sharp, great contrast and IQ. The 16-35mm give you 4-stop IS (almost) so you can shoot almost anything static without needing a tripod and get sharp images (varies from one to another).
With due respect, while fantastic for a full frame (on my list for next year), the 16-35/4 is an inferior choice in OP's specific case. All the advantages I mentioned for an f/2.8 lens WITH IS are valid, plus the OP wants to use it for portraits occasionally.
Of course, some times we just lust for L