I can't imagine why you'd want to get rid of the 16-35L II and get a 14L. The lens, 16-35L is a very sharp lens and I particularly enjoy having the zoom lens in that range. 14L is more of a specialty lens.
Honestly, I just got into photography a couple of months ago, so I haven't had an opportunity to compare or try out different gear yet. I've basically had my Tamron 24-70 f/2.8 VC and Canon 70-200 f/2.8 IS II, but I often find myself trying to push that 24mm even wider and the damn thing just won't budge!
Out of curiosity, how sharp is your 16-35 compared to your 24-70? My Tammy is noticeably sharper than my 16-35, especially between their overlapping focal ranges...
On FF, 24mm has a horizontal angle of view (AOV) of 74 deg. 16mm has an horizontal AOV of 98 deg. 14mm has an horizontal AOV of 104 deg. The fisheye will give you a horizontal AOV of 180 deg with a lot of distortion (not rectilinear). Fisheye pics can be "defished" but they become soft in the corners as the image is stretched into the corners. Sigma makes a 12-24mm lens but that still has a horizontal AOV less than 120 deg.
What AOV are you trying to achieve? If it's wider than 120 deg, your options are limited. Either defish a fisheye or start taking panos.
Thanks for the info, Random. I think my expectations were a little too high for this UWA, but since there aren't any camera stores where I am stationed overseas I really have no basis for comparison. Perhaps I should just play with it a little more and start doing pans like you suggested.
You may want to borrow/rent/order&return the 14L and test it thoroughly - that should help you with your decision.
I like my 16-35L, especially for its zoom capabilities but in terms of image quality I prefer my 24L. The 14L is supposed to be better than the 16-35L in IQ but only trying out the 14L will give you confirmation if it's also wide enough for your purposes...
I'd love to rent the 14L but lensrentals won't ship to FPO, therefore I've had to resort to online reviews and forums to aid in my buying decisions.
The 3x effective zoom range of the 24-70 is much broader when compared with the 2x effective zoom range of the 16-35. That along with the 8mm difference between the 16 and 24 could all lead to your disappointment with the new zoom.
If ultrawide is what you are seeking, I think the 14mm is going to serve you much better than a Fisheye. The Fisheye is the specialty lens, where as the 14mm is more akin to a wider field of view of your 24.
For the $300 difference in cost between the 16-35 and the 14, the $100 or so it will cost you to rent the 14mm adds 30% to your out of pocket. If your 16-35 is brand new, take it back to the store and ask to exchange it for the 14. If the store is agreeable to the exchange, bring your 24 along and you can do an in store side by side comparison before closing the deal.
I actually purchased the 16-35 from Amazon a little over a week ago, so I could ideally exchange it for the 14 if I wanted. However, I think I'll putz around with this zoom for a couple more weeks and see if that changes my mind. I might just keep it and add the 8-15 for those specialty shots, that way I'll have all those focal ranges covered.
So I just purchased the 16-35 II and to be completely honest, I was kind of disappointed to learn 16mm isn't as significant a difference from 24mm as I had hoped.