Posted 06 May 2012 - 06:17 AM
Although I shoot Nikon and have no experience with either lens, with the 16-35mm you gain 1mm on the wide end, which I would feel is relatively insignificant in most situations. With the 17-40mm you gain 5mm on the long end, which is enough to make a difference, and might make that lens better for some kinds of fish shots, like sharks. F2.8 vs f4? Your viewfinder will be a bit brighter with the 2.8 lens, but with the ISO flexibility of many newer cameras (like my D700) dropping to f4 makes less shooting difference than it used to. As to which gives you the better image quality behind a dome, I can't say.
Fred
Although I shoot Nikon and have no experience with either lens, with the 16-35mm you gain 1mm on the wide end, which I would feel is relatively insignificant in most situations. With the 17-40mm you gain 5mm on the long end, which is enough to make a difference, and might make that lens better for some kinds of fish shots, like sharks. F2.8 vs f4? Your viewfinder will be a bit brighter with the 2.8 lens, but with the ISO flexibility of many newer cameras (like my D700) dropping to f4 makes less shooting difference than it used to. As to which gives you the better image quality behind a dome, I can't say.
Fred