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A good friend recently brought to my attention a rumor of a 16.7MP Canon body on the way to market.  What impresses me about this potential development is that the camera is stated to be full-frame.  As any regular reader of this blog has likely noticed, I tend to think a lot about matters related to image quality; I am especially intrigued by diffraction (see here and especially here for my previous relevant comments).  Diffraction seems to be a big deal these days among photographers, especially among nature photographers intent on squeezing the last once of image quality for large prints out of their small sensors.

Yet, among the numerous books I have read over the years by such luminaries as Rowell, Shaw, and Adams, I do not recall any major diatribe regarding the evils of diffraction on image quality beyond more than a side-note.  I suspect this relative absence of concern is an artifact of the difference between digital sensors and their emulsion-based predecessors.

Film emulsions based on silver halide technology featured individual light-sensitive grains in the submicron range.  Even the dye clouds around the individual grains manifested at this extremely small scale.  Contrary to the pixels of current digital camera sensors, which range from 5 micros to more than 100 microns and are separated by quite discreet boundaries susceptible to the effects of diffraction, the silver halide crystals of film benefitted from their minute size and essentially random orientation throughout the emulsion.  The result was that the effects of diffraction, which physics assures us were certainly present, were largely washed out across the subatomic interstices of the emulsion.

The difference is further complicated by the fact that the typical digital camera sensor relies upon a Bayer array to replicate via interpolation the eye’s response pattern to visual light.  Film provided three separate color-responsive layers in the emulsion.  What so intrigues me about the Sigma’s Foveon sensor is that it offers a digital analogue to this aspect of film.  Nonetheless, the Foveon sensor is still limited by the size of its pixels.

Perhaps the most intriguing possibility of relevance on the horizon is the advent of quantum dot technology.  Its application to photography has the potential to surpass the grain limit of silver halide crystals while obviating the need for a Bayer array.  Such arrays of nanocrystals might be the next major evolution to photography since the rise of the first CCD and CMOS sensors.

It should be an interesting next few years.  In the meantime, I shall continue to look toward the horizon while remaining quite satisfied with the tools already at hand.

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