zeiss 18mm + 1d mark III

Does this combo make sense (over the 16-35 lens) for a wide angle to use with the apsh 1d3??

i'll use it for landscape, for low light fotography (during the night with natural light), and FIRST OF ALL i'll use it f in the winter mountain for sport photography (skier in the trees, freeriding ecc...) and landscape in the mountain...

16-35 is a better option for his AF???

i don't have any standard or wide angle zoom...only have 35L

The Zeiss 18 is a fine lens, but not Zeiss' best. It will be better than the 16-35 for landscapes but the latter is far more flexible. The primary point of concern should not be AF/MF (anything beyond a few meters is infinity for UWAs) but weather sealing. The Canon has it, the Zeiss has not. Then there's f/2.8 vs f/3.5 which often is the difference between getting a shot or not.

So, unless you are considering the Zeiss 21 f/2.8 I'd say go for the 16-35. It's not as bad as its reputation and it is very practical to have a zoom and it is weather sealed. You'll have to live with edges that aren't very sharp at f/2.8 but I think the other factors are more important for the type of photography you want to do.

If on the other hand you include the Zeiss 21 as an option then I would unreservedly recommend the Zeiss.

so...if we consider ony image quality...zeiss 21 is far better than zeiss 18mm???...and both are far far far better than 16-35 or just similar (i'll not see extreme edges, cause i use them on 1d3)

Well, that's difficult to say. I don't like to use the term "better" when comparing very different lenses. I prefer the look that my 21 gives me to what my 16-35 does. A lot of it is subjective of course. The 21 is sharper across the frame wide open. The 16-35 is not as sharp in the center and it gets worse to the edges. It is generally of course not fair to compare a top end prime with a zoom lens. The 16-35 improves a lot when stopped down - around f/8 it's difficult to tell the difference as far as sharpness goes. Beyond that there is a distinct difference in colors, contrast and bokeh. I definitely prefer the Zeiss there, but again, that's subjective.

The 18 vs 21 is easier to answer - they are similar in terms of colors and contrast but the 21 is superior in terms of sharpness and distortions.

If image quality is your only consideration (it shouldn't be) then the Zeiss 21 is the hands down best choice. The 18 is somewhat similar in style but does not share its optical excellence and the 16-35 falls behind the Zeiss 18. You should however definitely consider other aspects as well. You mentioned winter sports. Zess lenses are all metal - they become uncomfortable to operate in the cold. They are not weather sealed, so dropping your camera in the snow is a bad idea. Exposing it to rain is a bad idea etc

There is a very good reason why I'm keeping my 16-35. I use the Zeiss 21 when I have the luxury of good environmental conditions and time to play around with prime lenses. The Canon on the other hand can be subjected to harsh weather and it is a zoom lens which simplifies things a lot.

21mm is better but not as width on the 1dmarkIII.

it's like a 26.5 mm... wide...not superwide...could work...

so...for my pourpose 16-35 seems to be a better overall option: AF + versatility + weather sealing for winter mountain is very important...

i don't need extreme image quality at extreme edge, like you said, because of the apsh sensor...

but i like to have a very good wide angle with great image quality from TA...so IQ of zeiss 18 worth it?....aand teh IQ of the 21zeiss worth it??? for my pourpose obviously...

I would definitely go with the 16-35 for the flexibility of the zoom. I too am tinkering the idea of rebuying the Zeiss 18 again. As Denoir mentions, it's not the best Zeiss but gives decent results.

Here's a link of some images from this lens on a 5DC and 5D MK II. The photog actually works for Zeiss and his results are pretty impressive.Viewing the images really makes want to reconsider.
http://www.flickr.com …n/sets/72157622​236038659/