Monday, June 30, 2008
More than just megapixels—what you need to know about your digital camera’s core component
Canon has been developing and manufacturing its own CMOS image sensors for more than eight years and has optimized the technology. All current Canon D-SLRs use Canon CMOS sensors. Since Canon also produces its own image processors (currently, the DIGIC III) and A/D converters, it's able to ensure each piece of the system complements the others. The 21.1-megapixel full-frame sensor in the EOS-1Ds Mark III is the highest-resolution sensor in a 35mm form-factor D-SLR.
Being a major film manufacturer, Fujifilm went for a filmlike sensor. The company's color-negative film uses high-speed and low-speed layers for each color layer to extend the dynamic range; the Super CCD SR Pro sensor used in Fujifilm's current FinePix S5 Pro and IS Pro features high- and low-sensitivity pixels-unique octagonal ones in two sizes: 6.17 million large, high-sensitivity S-pixels and 6.17 million low-sensitivity R-pixels. The result is an exceptionally wide dynamic range, which has made the S5 Pro popular with pro wedding and portrait photographers.
Nikon has developed its EXPEED image-processing system to complement the new CMOS sensors used in its top D3 and D300 models, although the system will be used in all future Nikon digital cameras, too. The D3's 12.1-megapixel full-frame sensor contains the largest pixels of any current 35mm form-factor D-SLR (8.45 microns compared to the 5.49 microns of its D2Xs predecessor) and provides ISOs up to an incredible 25,600. The D300's DX-format (APS-C) CMOS sensor actually has more megapixels (12.3 vs. 12.1) and goes to ISO 6400. All other current Nikon D-SLRs use CCD sensors.
While other 35mm SLR makers adapted their film cameras to digital use, Olympus spearheaded the creation of the Four Thirds System, designing cameras and lenses from scratch specifically around a new sensor format. Advantages include lenses optimized for the image sensor, smaller components and an open standard (any manufacturer's Four Thirds System lenses can be used with any manufacturer's Four Thirds System cameras). All current Olympus D-SLRs use 10-megapixel Live MOS sensors, which feature a larger light-collecting area than conventional CMOS sensors, separate processing of chrominance (color) and luminance (brightness) signals, pixel amplification for bright display in live-view operation (which all current Olympus D-SLRs provide) and low noise, due in part to photodiodes deeply embedded in the sensor substrate to eliminate noise generated on the sensor surface.
Panasonic's Live MOS sensors (much like those used in Olympus D-SLRs, but working in-camera with Panasonic Venus Engine III image processors) offer the benefits of both CCD and CMOS sensors, combining high image quality with low power consumption and noise levels, and excellent color rendition. The Lumix DMC-L1 uses a 7.5-megapixel sensor, the DMC-L10, a 10.1-megapixel sensor. Both cameras provide live-view operation, the L10 with a tilting/swiveling LCD monitor.
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