Limits on a CMOS

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    • #48450
      AvatarAnonymous
      Inactive

      Hi All after testing my new JVC gzhm430I have a question &I hope someone can help me with??

      the limets of this camcorder is increible

      I cannot record any fast moving objects!

      I cannot record at parties in lowish light

      I cannot record anything with flashing lights,

      I cannot record moving objects that I need to pan the camera

      I cannot record anywhere anyone is using a camera with a flash!

      These are some of the problems im having in the short time ive owned the camcorder

      it looks like these are limits with a cmos sensor?is this so?

      Please can anyonetell me what I can recordwith this camcorder??

      Thanks

      Thanks in advance!

    • #199068
      Avatargldnears
      Member

      In general I’ve been led to believe that CMOS chips simply aren’t as seisitive as LCD’s.

      Your other gripes may be due to AVCHD video compression ( flash artifacts area fact of life in AVCHD-land ); and/or perhaps you’re trying to record rapidmovement in 24P?Maybe your camcorder will behave if you approach it on IT’S terms.

      Rick Crampton

    • #199069
      Avatargldnears
      Member

      ” In general I’ve been led to believe that CMOS chips simply aren’t as seisitive as LCD’s “

      OOPS! I meant to say CCD, not LCD . . .

    • #199070
      AvatarJaimie
      Participant

      Hi,
      Try setting the camera to 1080i to capture better fast motion. I don’t know if that will fix your problem, but I have found it better than any progressive setting for smooth fast motion. I have cameras with both cmos and ccd sensors and I don’t see a lot of difference between them although the cmos are slightly more sensitive.

      The real issue is more about noise. Is a grainy picture really all that desirable? There is some software that can reduce noise (Red Giant for example), but getting good original footage is always best.

      A trick you might try in low light situations is to set the shutter speed of the camera to 1/30 of a second if your camera allows it. Most cameras default to 1/60 of a second as their slowest speed, but often you can manually set 1/30. The 1/30 second will not degrade your ability to capture motion, but slower speeds will.

      Another trick is simply to stand closer to the subject so you can use a shorter focal length on your zoom lens. This helps because many zooms lose aperture as their focal length is increased (i.e. you zoom to a more telephoto setting). Using the shortest possible focal length gives you the widest possible aperture.

    • #199071
      AvatarRob
      Participant

      Your other gripes may be due to AVCHD video compression”

      No it’s not. The compression scheme has nothing to do with the issues he’s facing.

      It has to do with how a CMOS sensor “sees” incoming light. A CCD employs a “global shutter” while a CMOS employs a “rolling shutter.” The difference between the two is too much to explain, so Google the two.

      Each camera deals with the side effects of CMOS sensors in their own way. Higher end camera do a better job than lower end cameras.

      If you have a lower end camera, the best thing you can do is shooter a faster frame rate to reduce the side effects of CMOS sensors. Many people think you shoot a faster shutter speed….nope. Faster frame rate

    • #199072
      AvatarWoody
      Participant

      AVCHD is fine. Rolling shutter effects vary quite a bit with the quality of the sensor, which is a limit of the lower end cameras. This is why every time a thread pops up of what will be best for under a grand I would recommend a used GL2.

    • #199073
      AvatarJaimie
      Participant

      I was referring to reducing his low light problem by using the lower shutter speed. It would give an extra f-stop. Using the shortest focal length on the zoom may also, depending on the lens and the focal length he was using, may give as much as another f-stop. Neither of these tricks will do anything for the motion problems although the slow shutter speed may make them appear different.

    • #199074
      AvatarAnonymous
      Inactive

      Thanks for your replies guys!

      I’ve looked around on the net & found some examples of the problems http://www.youtube.com/watch?v=MF_9FhAlxi4

      http://www.youtube.com/results?search_query=cmos+rolling+shutter

      Rolling shutter effects is the problem! I find this great that JVC Canon etc do not make any note of these limits in any of the bumf it puts out?

      I suppose they would not sell any dodgy camcorders if they did!

      looks like I will be looking for a s/h CCD camcorder any suggestions??

    • #199075
      AvatarCharles
      Participant

      Panasonic HMC-150 is a very good camera with 3 CCD sensors and is good in low light.

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