Query on Shutter Speed Double Frame Rate...

Discussion in 'Digital Video' started by acearchie, Jun 6, 2011.

  1. acearchie macrumors 68040

    acearchie

    Joined:
    Jan 15, 2006
    #1
    I am aware that this is what should be done but I was wondering if anyone could explain what goes wrong if you shoot say 1/30 at 25fps?

    This is possible on a DSLR so what are the associated problems with doing it?

    Thanks
     
  2. Gymnut macrumors 68000

    Gymnut

    Joined:
    Apr 18, 2003
    #2
    I don't think there's anything necessarily "wrong" with this; Yes, 1/30 @25fps will introduce more motion blur, but this is a creative choice, albeit it one that may be best suited to being recreated in post as opposed to being done in camera; I edited a wedding/reception that the camera operator had slowed down the shutter down to 1/12 @24fps because he wanted more light during the reception; The result? Anyone moving looked like Casper and this was not fixable.

    Likewise, too fast a shutter will result in less motion blur, which may be desirable, however, in doing so ups the amount of light required to maintain proper exposure.
     
  3. acearchie thread starter macrumors 68040

    acearchie

    Joined:
    Jan 15, 2006
    #3
    I realise that it will add motion blur and shooting below 25/24 is not advisable as you will start having issues with your picture stuttering!

    However, is it the case that this rule related more to mechanical shutters and not electronic shutters as on the DSLRs?
     
  4. grooveattack macrumors 6502a

    Joined:
    Jan 9, 2008
    #4
  5. Gymnut macrumors 68000

    Gymnut

    Joined:
    Apr 18, 2003
    #5
    Yes this was derived from film cameras, based on a 180 degree mechanical shutter; However, having a variable shutter is not new and only specific to DSLRs.

    For film based motion picture cameras shooting at a frame rate of 24fps, one would think that each frame of film would be exposed for 1/24th of a second; However, with a 180 degree shutter, where half the time it is open or closed, additional time is spent having to advance the film through the gate to be exposed to light, so in actuality, each frame of film is exposed to light for 1/48th of a second. I believe the Panasonic DVX100 was the first video camera to offer 24p and while the guts of a video camera/DSLR are vastly different from a film based camera, intrinsically, the concepts carried over or were replicated in a digital form.
     
  6. KeithPratt macrumors 6502a

    Joined:
    Mar 6, 2007
    #6
    The 180°/double-Hz shutter is just what we've come to associate with the "film look". TV cameras usually shoot 50i with a 1/50th shutter, and that's the temporal equivalent of 24p at 1/24th.

    If the Canon DSLRs are doing it properly, 24p at 1/30th will be just a bit more stuttery and sharp than 1/24th.

    This is going off on a bit of a tangent, but at Cine Gear last week a company called Tessive were showing a product that has the effect of smoothing a shutter in and out. One of the gripes people had about digital cinema camera was that digital shutters didn't look as nice as the mechanical shutters found in film cameras. Tessive say their technology is better than both. Their demo video acts as a general explanation of shutters too.
     

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