vitorio wrote:The cameras are attached to the platen, which always seemed to me like the right way to do it.
It seemed that way to me too, and I built my second scanner with the cameras attached to the platen. I'm back to having the cameras on tripods, not attached to the platen. In my case, they're not even attached to the base, though I think that would be workable.
One problem which having the cameras attached to the platen introduces is that it's more difficult (and possibly impossible) to keep the camera and the book positioned the same way from shot to shot. The platen is placed on the book a little differently each time because it's being raised and lowered, and this affects how the shot frames the page.
My design also incorporated a floating platen, which amplified the problem. The Ion Book Saver would have the same problem.
A second problem, which didn't actually affect me while I was using this design, but which I realized with a book I scanned this week, is that the camera is typically restricted to landscape mode. Books which are wider than they are high will benefit from having a camera which can be rotated to shoot in portrait mode. Depending on how the camera is attached to the platen, this may not be an option.
Design can probably overcome these problems, even with platen-attached cameras, but I think maybe the best design solution is not to attach the cameras to the platen.