Wednesday, January 24, 2007
Buyer's Guide 2006: Today's Digital SLRs
Features and resolution distinguish the latest cameras
When light passes through the lens and hits the camera's CCD or CMOS sensor, an image isn't instantly created. Instead, the analog data produced by the light hitting the sensor is converted to digital using an analog-to-digital converter (ADC). The ability for the ADC to transform light to digital is the first critical step for a quality image.
The next step occurs when the on-board processor interprets that data and enhances the image file. Whether it's known as Canon DIGIC II, Olympus TruePic technology or something else, the camera takes the raw data and evaluates it for color, white balance, sharpness, tonality, contrast and color space. It's this processing of the image that can result in the distinct look produced by an individual SLR.
Although shooting in RAW leaves all this control in the hands of the photographer, the camera's on-board processing can nevertheless greatly impact your digital images.
ISO Sensitivity And Noise
Until recently, one of the significant advantages of film was its ability to deliver usable images at high ISO settings. With digital cameras, ISO settings of 800 and higher often resulted in excessive noise—multicolored specks that appeared in the frame. Especially obvious in areas with shadow detail, noise also could be found in areas of uniform color, such as sky or skin. The prevalence of noise would be a real distraction with enlargements.
Improvement in the manufacturing of image sensors along with the camera's built-in software has dramatically reduced the presence of noise at ISO settings as high as 1600. For photographers who shoot under low-light conditions or shoot long exposures, this improvement has been both anticipated and appreciated.
Performance And Speed
Speed and accuracy are the hallmarks of the autofocus systems found in current digital SLRs. Multisensor AF modules provide photographers with the ability to make off-center compositions with ease and precision, even under low-light conditions. And for fast-moving subjects, these systems, combined with a high frames-per-second burst rate, deliver a sequence of sharp images of even the speediest subjects.
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