DSLR sensor size tyranny
I was chatting with a friend yesterday who mentioned that a future digital camera might offer a larger sensor than the de-facto “full frame” size of 36 X 24mm. Indeed, most SLR lenses from Canon or Nikon or Leica might in theory cover a 36mm X 36mm area (though a few are squared-off in back, and corners might be quite poor). So why can’t we reasonably expect a 4:3 ratio (36mm X 27mm), or the large-format ratio of 5:4 (36mm X 30mm).
Color area represents 3:2 ratio eg 36 X 24mm
Gray area represents increased sensor area possible in a 36 X 30mm sensor.
Squarish ratios are better suited to many compositions, and would allow more megapixels without the downside of smaller lower-quality pixels. For example, scaling the Nikon D3 sensor to 36X30mm would yield 14.5 megapixels with no change to the pixel size. Corner performance might disappoint, but a lens that can cover 36mm wide should be able to cover 30mm high as well. The diagonal of a 36X27mm frame would be 45mm, versus 43.2mm for a conventional 36X24mm frame. The diagonal of a 36X30mm frame would be 46.9mm. Corners might be an issue optically, so perhaps 36X27mm would be a good compromise.
For that matter why are Nikon’s and Canon’s entry-level DSLRs limited to sensors that use 3:2? A squarish sensor would work there too, perhaps 24X18 or 24 X 20 or 22 X 22.
