>
>What processing capabilities? Don't they either store them in a raw
>format, or they use JPEG (which is a standard anyway). I can't see how a
>more expensive camera will yield better quality from that point. The old
>adages still hold true - a better image sensor ("film") and optics (lenses)
>will give you the shots you want.
>
>All the software and firmware does is coordinate it all.
There is a huge quality variation in digital cameras even amongst
cameras advertised as having the same number of pixels.
A 3 mega pixel camera typically does NOT have 3 million RGB pixels.
Usually each pixel only records one color, perhaps half the pixels
are sensitive to green, 1/4 to red, and 1/4 to blue. The sensor is
only sampling about 1/3 of the data you would expect it to.
The choice of how these pixels are arranged, and the software for
regenerating the missing data has a tremendous affect on image
quality.
The quality of the sensor affects image quality. What is the
underlying noise level of the sensor, and how does the firmware deal
with removing this noise, without removing detail from the image?
Higher quality sensors and better firmware yield better images.
How are the mechanics the camera? A 1/60th of a second exposure is
never exactly 1/60th of a second. How much of a variance does the
camera have.
How is the metering? Is it an average over the whole image, or are
there multiple zones? If it has multiple zones, the camera's
firmware examines the various zones and makes an exposure decision.
With a backlit subject, it is important that the firmware make the
correct decision.
How many bits of data per pixel does the sensor capture? 8, 12, 16?
More bits generally mean better images. How good are the A to D
convertors built into the sensor?
When compressing the images into JPEG format, what compression level
does the camera use? Does the camera sacrifice quality to reduce
processing demands, or does it offer the option of an image with
almost no loss of quality due to JPEG?
Last week, someone asked me if there was any difference between
Canon's consumer lenses and their L lenses other than the L lenses
offering a larger maximum aperture. Other than aperture it looked
to him like Canon's 75-300 consumer zoom was much better than the
70-200 f2.8L.
Just as there are many differences in lenses other that f stop, there
are also differences in digital bodies other than mega pixels.
-Michael Fryd
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