I was looking at some lens specs and noted that the exit image is circular which is then projected onto a rectangular sensor. Could they make a circular sensor to capture the whole image or at least more from the lens?
This idea has come up in internet forums every month or two for years and yet no sensor maker has done it, which already tells me that it is either bad or impractical. I suspect that the reason is, in part, that IC's including sensors are cut in rectangles from larger wafers, and have photosites arrayed in straight lines for readout down columns or across rows, and with wiring along one or more of the straight edges. A circular chip would really have to be a square, or cut down from a square, so it makes more sense instead to use that entire square, or some other rectangle that cover the needed parts of the image circle, with some overflow.
In fact, Panasonic does this with the sensor for the GH1: it is larger than the image circle specified for the m4/3 lens system, so can record all the most common shapes (4:3, 3:2, 16:9) in sizes than span that entire image circle on their diagonals.
BTW: square sensors are another bad idea that comes up as someone's brilliant new idea in forums every few months, despite the photographic industry having moved solidly away from square format, starting back in the film era. (Except for some "non-artistic square photographic equipment" for X-rays, astronomy and such.)
