Forgot to mention that it preferably should be compatible with FF body. So even though 10-22 is good - I need other options, so that I don't have to sell the glass when I switch to FF.
Forgot to mention that it preferably should be compatible with FF body. So even though 10-22 is good - I need other options, so that I don't have to sell the glass when I switch to FF.
If you want an ultrawide lens for APS-C that's also FF-compatible, since 'ultrawide' on APS-C means <15mm, you have two choices for zooms (one rectilinear) and two for primes. The two zooms are the Sigma 12-24mm and the Canon 8-15mm f/4L Fisheye, and the two primes are the Canon 14mm f/2.8L II and the Samyang 14mm f/2.8 (the latter being inexpensive but fully manual, aperture and focus). The Sigma 12-24mm is slow and soft, the 8-15mm is a fisheye, the 14L is very expensive, and the Samyang suffers from wicked-bad moustache distortion which is hard to correct in post.
Given those choices, I'd pick up either the Sigma 8-16mm or the Canon 10-22mm, and sell it if when going FF. The Canon lens, in particular, will hold it's value well - I bought mine new, sold it a year later for a loss of $50, and if I was selling it today, I'd make a profit given the recent lens price increases.
For clouds, using a tripod with a rotating element to allow you to turn quicker, and thereby shooting the photos quicker after one another.
Waves will be too erratic. What you could do if the clouds are still, however, is using a long (10seconds+) exposure to let the water movement blur out. That way, stitching the water together should be easier (though may still require some editing). This would obviously also require a tripod, and probably some ND filters too.