The APS-C CCD sensor of Nikon D200

Presented in November 2005, The Nikon D200 confirms the will of Nikon to propose only sensors APS-C for all its Digital SLR when Canon chooses the sensor full format 24x36 for its EOS 5D.
Canon seems to reserve the sensors full format 24x36 for pro cameras and sensors APS-C for amateurs. This strategy seems very relevant, point of situation:

CCD versus CMOS sensors. CCD versus CMOS sensors CMOS sensors have many advantages on the CCD: more industrial manufacturing with built-in functions in the microchip itself, the same manufacturing process as for the microprocessors, good reaction to the strong luminosities, electric low fuel consumption and capacity to recover information pixel by pixel, which allows to resize the image (example Nikon D2X) and to transfer only useful information. The youth defects of the CMOS from now on control, the production costs fall and the sensitivity of sensors CMOS is comparable with that of the CCD. They are already generalized for all the pros DSLR and should "go down" towards the amateurs DSLR. Race to the maximum resolution: which number of pixels is optimum? Even if 10 or 12 million pixels sensors answer in the majority of the professional and thus amateur requirements, We can think that the race to a highest resolution will continue, more for reasons marketing than practical: This race allows Nikon and Canon to remain at the head, it will be the sales point number one for the renewal of the park or for a first purchase; like the power of the microprocessor is the argument number one for the purchase of a PC. A great number of pixels will make it possible to complete an optical zoom with a digital zooms. The Nikon D2X already does it. Tomorrow with a sensor of 25 or 30 Mpixels, the digital zoom could be of 4 times without degradation of the image. The resolution of DSLR should thus continue to increase.

Canon EOS 5D CMOS 13.3 MP, 8.2 x 8.2 µm Nikon D2X CMOS 12.8 MP, 5.5 x 5.5 µm

Which sensor for which resolution. The continue increase of resolution poses many problems however. The background noise and the resolution are directly dependent on the physical size of the pixel. For the sensors 24x36 the ideal size seems to be close to 9 µm: smaller the pixel has difficulties to collect the photons and a background noise is generated, broader, the diffraction is too strong. Finally let us recall for the photographers, that more the sensor is small plus the depth of field is large and thus more it is difficult to emphasize a subject. The CMOS of the camphones do not require focus, all is focused. This ideal size is also function of quality, lens resolution themselves: the lower the size of the pixel is, the more lenses must be discriminating to target the good pixel and not "to dribble". You have just to compare an image taken by a six million pixels DSLR with the same done by a six million pixels compact "to see" immediately the difference. Problems of incidental rays are to be added... Nothing is simple. To know more, it is advisable to read in French the "Numerical Course of Photography” of René Bouillot

Tentative of conclusion (November 2005)

Concerning the DSLR, Olympus that choses, for its system 4/3, a small sensor will be penalized by this initial choice and does not have an upgrading capability. The 8 million pixels sensor of E300, E500 is undoubtedly the limit with their 5,5 µm and their micro lenses network which limits the wide-angle lenses.
Nikon with its APS-C sensor arrives at the same problem but for 12 Million pixels. Canon has been just freed from this constraint by proposing on the Canon 5D a full sensor CMOS 24x36. Such a sensor would make it possible to reach resolutions of 26 Million pixels.
If the resolution of DSLR increases, Nikon will be obliged to also pass to "full format" sensors. That can be done without problems except for DX lenses that would become unusable.
In the future, for Canon and Nikon, two parallel series of DSLR may exist, the APS-C for the amateurs, the "full format" for the professionals.

pierre j.

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Created in October 31 2005
© Pierre J