TheQ

I saw a comment about April in forum as well, which would be about right based on Canon's annoucement to availability track record.

From similar, sometimes not so reliable sources, the US price should be around $1400-$1450.

Assuming the lens diagrams on Canon Museum web page are to scale (a big assumption perhaps), the EP for the 17-40 is ~74mm and the EP for the 16-35 is ~80mm. I have no idea at what focal length the elements in the diagrams are set to so there is no way of knowing what focal length (if any) the element positions represent.

162.6-74=88.6 > port entension = 46mm
162.6-80=82.6 > port extension = 52mm

A 49mm extention could be better for both lenses. I'm going to work on getting the camera underwater with the longer extension.

I am running into the same issue with blurred edges with the 5D with the 16-35. It is not a DOF issue... even at F4 the DOF in that image should be around 10ft, which should be more than enough to have held detail in most of the blurred areas. I posted a sample in this thread.

I have tested with +2 and +4 diopters and while helping, they don't fix the problem.

Ferg's results seem suprisingly good to me. The right edge of his image is very close to the camera. Perhaps the problems starts when the subject is further away? Ferg, do you have any other samples you could post?

Ike, do you have any suggestions? Getting good UWA results with the 5D is a problem that has me stumped. I'm either doing something wrong or there is some other variable causing the issue.

I have tested the 16-35 behind the Ike 8" dome and the diopters help corner sharpness a bit... but not enough.  I'm still looking for ways to improve my results.  I have not had a chance to test the 17-40.  It would be interesting to see in water results with it.  Scubastu seems to be getting better results with 16-35 behind the Subal 8" dome in his enclosure (is the Subal dome glass?).

I find the one-shot AF mode works best for macro.  Once One-shot AF gets me close, I move the camera back and forth to fine tune the DOF range where I want it.

I am very happy with the 5D/Ike viewfinder combo.

The 16-35 does produce good edge to edge results on land. Underwater, I'm seeing refraction blurring at the edges. It is not DOF blurring.

The +4 on the 6" does produce the sharpest results, but I didn't like the barrelling it added. Admittedly, barrelling isn't much of an issue underwater.

This picture is an example of the blurring that I'm referring to
(16mm, f/5.6, 8" dome w/+2 diopter):