FYI, the 400D Av button, shutter button, AF focus selection button, AE lock button, and all the directional buttons are in the same place. I have tested these out in my S&S 350D housing and the Av button is fully functional without any modifications. I don't know the button arrangement in the Ikelite, but I would presume they would function. It's the left rear buttons that do not line up (that and the new shutter drive button)
Thanks pakman.
Good news for me. One of my main concerns was the av button because I usually shot in manual mode.
In the ikelite all the buttons you mention are direct ones but the Av button, so with these there are no issues.
The Av button is an especial one, in order to remain pushed for aperture changes with the dial when using the camera in manual mode. This button are pressed by a rotatory shaft that can you you must to pull in order to allow rotation. If this button is aligned or in the bounds of the circle area given by the bended shaft, there won't be any issue too and any little misalignmet can also be easily fixed.
The left buttons are not vital, but many times I like to check histograms and any other info of the fotos (including zooms) and erasing underwater photos underwater. Yes, I know I need a bigger card but this also means bigger messes when I forget cleaning the card after dowloading the pictures
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But I think that this can be fixed using a transfer pad or even just changing the rubber tips with especial ones.
The only button unavailable would be the Drive mode button. This is the only one button that I've never used it underwater but I won't discard that I'd use it int the future if it'd be available.
I hope to have my 400D soon , so I hope to confirm all these things by then.
Rai