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Best progressive scan video camera?

Discussion in 'Projectors, Screens & Video Processors' started by Squash_pro, Mar 25, 2001.

  1. Squash_pro

    Squash_pro
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    My wife creates video slideshows for athletic teams, cheerleading squads, and other groups interested in having a video to celebrate and commemorate their time together. Most of her videos are collections of still pictures set to music, with transitions and short sections of live video thrown in to add interest. One of the problems that she faces in making her videos is in capturing sharp photos in poorly lit gymnasiums. Even with expensive digital cameras, it is difficult to stop the action under such circumstances. It is also difficult with digital still cameras to get the shot to occur precisely when you want it to. Often the shutter delays cause the captured still to be after the desired action has been completed. To counter this problem I have been investigating the usage of video cameras to capture good stills for her videos. I have done some experiments with interlaced video and have found that movement causes problems in doing high quality frame captures. Although one can de-interlace in Adobe Premiere, this is accomplished by dropping one field, resulting in an effective resolution of 360x240. This is not acceptable. The progressive scan mode of video cameras like the GL-1 is interesting in this regard. If this mode is truly progressive scan, i.e., capturing all 480 lines in a single pass, then such stills would appear to be perfect for her usage. This would also solve the problem of capturing action shots at the exact moment that the critical action occurs. However, I have heard that the frame mode on the GL-1 may not be a true progressive scan, that it may be accomplished by a simple interpolation of a single field. Does anyone know if this is true or not? Does anyone know what resolution can actually be achieved using frame mode on a GL-1? Are there any cameras that anyone would recommend that have a true progressive scan mode that works well for the purposed described? Does anyone have other approaches that they could recommend to achieve our goals? Any help in this regard would be greatly appreciated.
     
  2. Squash_pro

    Squash_pro
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    Thanks to everyone who has replied already. I have seen the replies in email, but for some reason I don't yet see the replies on the bulletin board.

    I have some comments and questions regarding Don's reply (hopefully it will get posted soon for everyone to see as it was quite insightful). Your observation that film with high ISO numbers does best in low light is right on the mark. However, this is an expensive route for my wife to take because of the film and developing costs. It also adds an extra step of digitizing the photos either by scanning or by taking a video still of the photo with a video camera. Hence she has a strong motivation to get a digital solution to this problem.

    I followed your excellent write-up of the GL-1 processing technique until the last paragraph. You wrote:
    "Thus normal frame mode provides a nominal 480x720 pixel resolution of still objects (one field)and 240x720 of moving objects (one frame) while frame mode orivudes a nominal 360x720 pixel resolution of moving and still objects."
    I am assuming that your "normal frame mode" is referring to interlaced mode, where you get the benefit of both fields with still subject matter, but where you are forced to use only one frame to eliminate motion artifacts with moving subject matter. The "frame mode" in the last sentence would be the GL-1 resolution achieved by their pseudo-progressive scan mode. Is this what you meant?

    I am also wondering about the true progressive scan that you mention with the Optura model. Would this yield a true 720x480 resolution for moving objects? If so, this might be a better option than the GL-1.

    I have also looked at the Sony VX-2000, which claims a progressive scan mode of 15fps. Do you know if this is true progressive scan? Would this yield full resolution 720x480 on moving objects at 15fps?

    I am also wondering about the effect of different shutter speeds on these video cameras. My impression is that shutter speed is per field event, i.e., that a high shutter speed with interlaced video will yield two individually sharp fields for each frame. However, with moving objects one will still get the interlace issue as the fields were captured at different points in time. The GL-1 appears to circumvent this problem by collecting the fields at the same instant in time. I am assuming that all the progressive scan modes on all the cameras would work the same way, and that fast shutter speeds would result in the best possible freezing of the action (assumes enough light is available). Is this correct?
    Thanks again for all your help. Anyone else with knowlege on this topic is encouraged to respond as well.


     

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