What does Progressive Scan mean?

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The Sony DSC-700 has a " 1/2" 1.5 million pixel progressive scan CCD" What does this mean? Will this camera require delays between shots? I read that the Kodak DC260 requires 30 seconds between shots, which I consider unusable.

-- Scott Cother (scott_cother@hotmail.com), September 30, 1998

Answers

Hi Scott,

First, many thanks for your excellent answers to others questions here!

Progressive scan really isn't a particular issue with typical digital still cameras. It refers to the distinguishing difference between video CCDs and those generally used for digicams. Video CCDs use an "interlaced" scan, which scans every other row of pixels in each pass, rather than every row each time (progressive scan). Interlaced scan CCDs can produce strange "tearing" artifacts with moving subjects, progressive scan devices (mostly) won't. Neither type of CCD scan has any impact on the inter-shot timing of a digicam: That parameter is more a function of available internal buffer memory, camera CPU speed, etc.

Inter-shot timing varies *widely* between cameras, and usually isn't reported on. In our early reviews we, too, overlooked this, but have been recording it for recently-tested cameras. The DC260 has a fair chunk of buffer memory in it, letting you take two high-res images pretty much immediately after each other (allowing a second or two for autofocus, autoexposure, etc), but after that you have a *long* wait before the next one. (See our review of the 260 for specific timings.) Some newer cameras are beginning to address the need for rapid exposures. Some cameras offer a "burst" mode, in which they'll take low-res images in very rapid succession. Olympus' about-to-be- announced D-600XL will take up to 5 high-res images in very rapid succession. (But the 600XL supposedly won't be announced until sometime in November in this country.)

Hope this helps - check our reviews for inter-shot timing, you should find it for most of the megapixel-class cameras.

-- Dave Etchells (web@imaging-resource.com), September 30, 1998.


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