Questions about 16-35 F/4 IS

Hello community,

I have a couple of questions on this lens. It seem to be an interesting product for my needs (landscape photography). Not super heavy (600 g), people say it is very sharp, 77 mm filters, etc.

I have been doing all my landscape work with 24-105, which is not perfect, but I would a way to work around it's weaknesses and produce satisfying results. I was waiting for Canon to produce the 14-24, but it might never happen.

I have 2 questions:
1. Sharpness - how would you compare it to Zeiss 21 or 17 TSE?
2. It is plastic, but would you say it is a quality product that can survive arctic weather?

Thank you for taking time.

1. It's at least as sharp as the Zeiss 21 with both at F/4 and a touch softer in the extreme corners than the 17 TS-E.

2. It is plastic but it's the kind of plastic you'd feel safe cracking a polar bear over the head with =). In reality I'd expect plastics to actually be better for extreme environments like that since there's less thermal expansion.