The CMOS Sensor Squared [CR2]
By| May 13, 2010
This is a leak from an unnamed camera manufacturer about square sensors.
We have heard in the past that the 1Ds Mark IV would have a square CMOS sensor. Most people dismissed it as poppycock.
This rumor may appear to be in a different format that previous rumors, however this is how it was sent to me and I was told to post it as such.
by Dean Francis
Camera image sensors commonly use rectangular formats (3:2, 5:4, 16:9 aspect ratios). However, to obtain the highest image quality, the square format (1:1 aspect ratio) should be used. The advantages are surprisingly extensive as outlined below:
MAXIMIZED FIELD OF VIEW
The square format covers 100% of the maximum field of view. The maximum FOV is the largest area that can be covered by any four sided sensor (see diagram). A rectangular format (3:2) uses only 89% of the maximum FOV. Simply stated, the wider the rectangle, the smaller the photograph. The square format is about 11% larger – a considerable amount of image data.
PERIPHERAL LOSS MINIMIZED
Generally speaking, image quality suffers along the outer third edge of lenses. That’s where any circle of confusion (COC) issues become readily apparent, such as blurring, chromatic aberration, distortion, vignetting, etc. A rectangular format actually pushes outward into that area of the lens. 18% of the image (4 corners & 2 sides) are clearly degraded. However, the square format eliminates degradation (all 4 sides) and minimizes the remainder by pushing it farther into the corners.
MICRON GAIN IN RESOLUTION
Photo sites benefit dramatically when their size is increased. The square format has a surface area 12% larger than a rectangular format (3:2). Photo sites can be manufactured 12% larger, a gain of +1.12 per micron. The 12% increase also expands sensel (super pixel) variations of resolution and enables 16 bit RAW capture when coupled with improved binning algorithms.
CROP LOSS SOLVED
Cropping a landscape oriented photograph (3:2) down to portrait discards about 60% of the image data (see diagram). With a square format, only 20% is lost. Landscape vs. portrait orientation can be determined later based upon output. Once cropped, only 3% of the peripheral loss region remains (extreme corners).
Photographers no longer have to rotate the camera and the secondary portrait grip becomes a thing of the past. Also, the quantity of materials is lessened (about 10%) by shortening the toe, foot and heal of the bottom plate. Weight is thereby decreased, allowing for significant changes and reallocation of the source/component materials. Additional battery capacity can be maintained and/or relocated to a secondary or supplemental location. The sensor is also cooled more evenly (about 5%) by equidistant dissipation of heat through the mount.
The list of improvements for the square format is extensive, benefitting camera functionality in all photographic and video applications. It’s also highly cost effective from a materials/manufacturing standpoint, desirable from the consumer’s viewpoint and fully marketable as a standardized format. Dean E. Francis