Sony’s Alpha A700; A Remarkably Fast 12-Megapixel D-SLR Page 2
The Sony A100 received accolades for its Super SteadyShot stabilizer that also provides automatic dust removal by vibrating the (antistatic-coated) sensor. The A700 includes both features but employs a more effective Anti-Shake system that can dampen more high-frequency vibration. According to Sony, the new system provides up to a four shutter speed step advantage over non-stabilized equipment. I made many sharp photos at a 1/8 sec shutter speed when using a 70mm focal length (105mm equivalent). Switching to 1/4 sec still allowed me to make some photos that are adequately sharp for nice 5x7" prints.
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Increased Speed And Efficiency
In order to provide great speed and superior image quality, the A700 employs
entirely new technology, starting with a CMOS (not CCD) sensor that provides
some preliminary data processing. The 12-bit A/D (Analog to Digital) conversion
occurs right on the new "Exmor" silicon chip instead of a separate
A/D processor, for greater overall speed. According to Sony, this technical
approach also provides "rich tonal reproduction" and less digital
noise because of cleaner analog data and a "shorter signal path."
There's also an improved BIONZ processing engine using Large Scale Integrated
(LSI) circuitry for greater speed, two-stage noise reduction before raw data
conversion, and less power drain. This processor also allows for a more versatile
Dynamic Range Optimizer (DRO) that applies image adjustment curves for better
shadow detail and contrast. Advanced mode is the most effective, since it analyzes
1200 segments in the frame. With the A700, the user can select any of several
DRO levels--or set DRO Bracketing for three shots--for just the right
increase in shadow detail in very contrasty light.
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The combination of new sensor, processor, and a larger buffer (temporary storage bank) combine to generate an "unlimited" number of Large/Fine JPEGs or 18 raw files in a single burst at 5 fps (frame per second). (For the greatest burst depth and recording speed use a 166x to 300x CompactFlash card instead of a Memory Stick Pro/Pro Duo.) Because autofocus must be quick in order to keep up, it's activated immediately with the Eye-Start feature. Sony developed a new focus mechanism, faster AF microprocessor, improved algorithms, a more powerful infrared focus-assist lamp for low light, and a new 11-point AF sensor. The central focus point includes two horizontal plus two vertical sensors that allow for quick focus acquisition on virtually any type of subject or pattern.
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Performance And Image Quality
During extensive shooting, the Sony A700 lived up to its billing as a fast,
versatile camera for serious photography. It started up in a 1/2 sec, activated
AF instantly, responded without any apparent shutter lag, and was almost always
ready to shoot another long burst. Autofocus was fast, accurate, and reliable
even in dark locations. Tracking focus performance in action photography was
very good with an affordable Sony AF 75-300mm f/4.5-5.6 zoom. The camera's
new AF system also provides a bonus when used with an f/2.8 or wider aperture
lens: superior focusing accuracy with the dual cross-hatched central AF sensor
point.
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