And here's my super quickie sharpness offering.
I didn't have a 16-35 to compare this against, so I compared it at 24mm against my 24-70 F/4L IS.
* Both lenses set to 24mm
* Taken at F/4, F/5.6, F/8, F/11
* Tripod, cable release, LiveView focusing, etc.
* Aperture priority @ standard exposure
* Did not have peripheral illumination on
* RAW processed in ACR, sharpness set to 50 and everything else was default; no lens correction profiles were usedhttps://www.flickr.com/photos/66374817@N04/14546466862/sizes/o/
What you'll see here are the actual 1000x1000 pixels in the corner of images captures at four different apertures on two different lenses. Make sure you click on the 'original' size at the top to see this without downsampling problems.
Note that at 10x, I was focusing on the boards
of the bench, not the ground behind the bench.
Clear limitation: I was in a mad rush (the rental is due back tomorrow) so I shot a scene without a clear near-infinity planar target (like a house). It was a park bench that was within perhaps 5-6 feet of the camera. So I actually LiveView focused at 10x in the corner itself
(on the bench boards as said before). So these shots were not
center focused -- they represented the best focusing I could get in the corner of interest.
My thoughts were good ones. The new 16-35 F/4L IS lens out-resolved a very sharp L zoom at 24mm in the corners. That and my other finding about vignetting with a Lee filter holder...http://www.canonrumors.com/forum/index.php?topic=21554.msg409701#msg409701
...has me leaning strongly towards buying this lens.