Tech Ques: About 1-ccd, 3-ccd, sensor filters, etc

Discussion in 'Digital Cameras' started by Miguel Gonzalez, Jun 3, 2004.

  1. A friend and I are having an on-going discussion of which
    system (1-ccd or 3-ccd) systems are 'inherently' superior
    vs. the 'reality' of implementation of these systems.
    (I believe the actual 3-ccd systems seem to be superior
    but they are also significantly more expensive, so comparisons
    are not really equal)


    It seems that it is only VERY high-end still cameras use
    a 3-ccd system, as well as fairly pricey semi/pro type
    camcorders use the 3-ccd system.

    The 'resolution' of the 3-ccd camcorders are still 'way' less
    than the 6,8,etc mp still cameras, that I have seen.


    Here's the basic question:

    1-ccd systems have an inherent 'blurring' of the image
    (the color sensors are spread physically) vs. the
    necessity of a 3-ccd sys. must be 'aligned' very precisely
    to not be blurry to the same degree (the color sensors are
    effectively stacked in a column).

    The real argument is whether a 1-ccd CAN be as good as a
    3-ccd system (will the technology of a 1-ccd sys ever
    allow it to be as good or better than a 3-ccd system
    assuming a similar price of both)?

    Another issue is, does the 1-ccd system HAVE to be more
    sensitive to be equal to a 3-ccd? (very little light loss in
    a set of prisms vs. the physical spread of sensors in a
    1-ccd system and it's theoretical reduction in light)?



    Thanks for some good technical info, as I can't find this
    comparison via Google and its nagging me!

    Thanks!
     
    Miguel Gonzalez, Jun 3, 2004
    #1
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  2. At a fixed resolution, a 3CCD system will produce a better image than a
    Bayer 1-CCD sensor, but the 3CCD system will cost more. At a constant
    price, though, you can have a lot higher resolution Bayer sensor than a
    3CCD beamsplitter system.

    For video photography, the output resolution is fixed, so the primary
    benefit of extra pixels in a Bayer sensor is mostly lost. The primary
    benefit (better colour) of the 3CCD system is retained. Thus, if you're
    shooting video and have lots of money, you should build a 3CCD camera.
    (You *could* use a higher-res Bayer CCD and then downsample it 50% to get
    just as good colour, but the higher-res CCD is less sensitive to light
    than the 3CCD setup, and this isn't good in an environment where the
    longest shutter speed is 1/30 second.

    For still photography, more resolution is always useful (at least with
    the sensors available today), so it makes sense to use a higher-res
    Bayer sensor than a lower-res 3CCD system at the same price.
    At the same price, a Bayer CCD can be much higher resolution.
    For still photography that's useful, for video it's not.

    Dave
     
    Dave Martindale, Jun 3, 2004
    #2
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  3. Miguel Gonzalez

    Bill Funk Guest

    This is called *vaporware*.
     
    Bill Funk, Jun 5, 2004
    #3
  4. Miguel Gonzalez

    Dave Haynie Guest

    Yup. The real question is, what are your limits.
    Which, these days, means "$700 or more" -- 3CCD models are not all
    $2000+ cameras...
    Of course, for the money, you may also buy a larger single-CCD, versus
    three smaller CCDs plus the diachroic prisim.
    Yup. There have been a few 3CCD still cameras. But when spatial
    resolultion is actually more important. If you're a human, and are at
    least in the megapixel range, you will always get a better image by
    adding spatial information in favor of color information.

    One of the video magazines just did a review of the Canon Optura Xi,
    which is a megapixel, single-CCD camcorder that's downsampling the
    whole larger CCD (I think it's around 2Mpixel) when in video mode.
    It's in all other ways a fairly high-end prosumer camcorder, about a
    grand sold new. They compared it to several 3CCD cameras. Every
    reviewer (all serious video people) was able to pick out the Canon
    from the other camcorders. But they admitted it was very close, that
    the Canon was the best single CCD camcorder they've seen, and that
    other factors could have been at issue (perhaps the 3CCD cameras were
    simply better cameras, they didn't elaborate).

    So for video, it's possible, though not there yet. I'd like to see how
    something like the JVC HD-DV camcorder, which is essentially a
    prosumer HD camcorder, but very much in competition with 3-chip DV
    cameras on price, would compare when shooting in DV mode. That one
    uses a single CCD. It's actually a bit smaller than the 1280x720 of
    the 720p mode they shoot, so just under 1Mpixel, and it uses an odd
    color mask, where some of the pixels aren't masked at all...
    apparently designed to work into the 4:1:1 or 4:2:0 descimation you're
    going to have on DV or MPEG-2 in the modes supported.

    Dave Haynie | Chief Toady, Frog Pond Media Consulting
    | Take Back Freedom! Bush no more in 2004!
    "Deathbed Vigil" now on DVD! See http://www.frogpondmedia.com
     
    Dave Haynie, Jun 6, 2004
    #4
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