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  • CMOS?

    Could someone, please, help me understand why CMOS is important in digital cameras? I am not sure I eve understand what CMOS is.


    I appreciate this educational opportunity.






  • #2
    Re: CMOS?

    It's not, exactly.


    The sensor used to capture the image in current digital cameras is usually either a CCD chip or a CMOS chip; there are some other specialty ones, but these are the major ones.


    But the system is far more important than what the sensor is made of. CCDs have somewhat more static, and attract more dust--but have less noise. The software/firmware between the raw sensor and the output file can have far more impact on the results than the actual sensor. (Or much less-it depends a lot on other stuff.)


    If it helps, think of the sensor+electronics+software as the overall equivalent of film+developer. There's no direct mapping between sensor and film in the Real World(tm); that's a theoretical map that only applies if you don't have it in a camera system--and thus, not available to a non-lab-based photographer.


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    • #3
      Re: CMOS?

      Which gives the sharper image....CMOS? One of the new cameras coming out (and I don't remember which) has a CMOS chip and come to think of it, doesn't that apply to the 760?


      Thanks, Kevin!


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      • #4
        OK, good question, here we go....

        (CCD) stands for "charge coupled device". Where as (CMOS) stands for "complementary metal oxide semiconductor". Which one is better??? Well that depends, they both have strengths and weaknesses.


        CMOS uses about 1/10 less power, usually cost less that CCD because they use the same technoligy as CPU's and RAM memory, and, well, it get's technical, but it has more stuff or circuitry on the chip. Some say this extra stuff on the chip will produce BETTER images.


        On the other hand, CCD has been mass produced for a long time now. IT'S a proven system.


        CMOS in the past were reserved for Web cams and Survalence cameras. The problem was that most CMOS chips produced a lot of NOISE. Well Canon fixed that by some type of SCANNING thing that's done on every pixel before and during exposure.


        Bottom line is They fixed the NOISE.


        Does that help???


        Kirk





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        • #5
          Between you and Kevin, I got it. TYVM!!!!!! <img src=http://www.pro4um.com/images/nm.gif border='0'>

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          • #6
            You're WELCOME <img src=http://www.pro4um.com/images/nm.gif border='0'>

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            • #7
              Re: CMOS?

              It's not really a useful question, unfortunately. It's like asking whether Chevrolet makes faster cars than Ford.


              The best of both are excellent; the worst of either is pretty darn poor. The entire system is what makes an image that can be used, and a raw sensor simply captures light hitting them.


              The more sensor 'cells' (usually called 'wells' as that's what they are from an electronic/chip design standpoint) there are, the more pixels you can potentially get, but there are so many factors in just that that even that one issue isn't clear. (cf. Foveon or multi-shot camera backs)


              I'd like to give you a simple answer, but it's not something that I can honestly summarize without just plain lying; every simplification I can think of is wrong in some serious ways.


              If you think of the whole imaging system as a whole unit, you'll be better off. Otherwise, you're stuck dealing with 'well the Ford XYZ engine is better than Chevrolet's, but the Chevy transmission is better, while the ....'. You-as-a-driver purchase an entire car, not just a transmission, engine, suspension system, etc. Asking if camera A is better than camera B for pixel count, overall resolution, speed of capture, etc. is somewhat meaningful. Asking anyone other than a chip designer about the advantages of CCD vs MOSFET vs CMOS vs etc. isn't useful. It seems like it would be/should be, but it's not--because you-as-a-photographer can't do anything with a sensor without the entire support package (AKA the rest of the camera).


              Background: until Monday, I worked at a company that designed software to help people design computer chips. I'm NOT a chip designer, but have some familiarity with the low-level issues involved. (That may be why I can't just say X is better.)


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