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Shutter speed and fps relationship

Discussion in 'Filmmaking' started by teddoman, Apr 4, 2013.

  1. teddoman

    teddoman Mu-43 Regular

    191
    Mar 22, 2013
    nyc
    This may be a dumb question, but does the fps you choose also force you to set a shutter speed minimum floor? If you're at 60 fps, for example, doesn't that mean each frame cannot be longer than 1/60? Otherwise, you couldn't fit 60 frames into a second. Likewise, 30 fps requires a min shutter speed of 1/30. And 24 fps requires a min shutter speed of 1/24.

    What happens if you set your camera shutter speed below the required minimum that is set by the frame rate, if there is such a minimum?
     
  2. swampduck

    swampduck Mu-43 Veteran

    334
    Mar 29, 2013
    Taneytown , MD
    Dan
    FPS is a measure for how many shots you could take per second. It is dependent on the f stop used though. The lower the shutter speed, the further away from "max" fps you could acheive. But also remember with digital it is also a mechanical consideration, ie, how fast can the camera read and write to the card and the size of the camer's buffer. That is why we will sometimes see xfps .jpg and a different xfps raw.

    That is my thought on it, others may be more knowledgable
     
  3. klee

    klee Mu-43 Veteran

    367
    Mar 20, 2013
    Houston, TX
    Kevin
    my OMD in movie mode does not allow shutter speeds slower than 1/30
     
  4. swampduck

    swampduck Mu-43 Veteran

    334
    Mar 29, 2013
    Taneytown , MD
    Dan
    Maybe i should check the forum a message is in before responding:doh:

    My post is irrelevant, sorry
     
  5. RobWatson

    RobWatson Mu-43 Hall of Famer

    I suppose one could set shutter speeds faster but the results can be odd. Imagine 30 fps but with 1/2000 sec shutter. I'd expect a Ray Harryhausen stop action claymation kind of look to the motion. There are some youtubes showing this type of movie. They look 'wrong'. Everything seems to be moving at the right speed (not like time lapse) but it just does not look right.

    Pretty sure electronic shutter is the goto for this type of shooting.
     
  6. teddoman

    teddoman Mu-43 Regular

    191
    Mar 22, 2013
    nyc
    I know you can go with pretty much as fast a shutter as your camera can shoot. There's really no maximum shutter speed, if you camera max is 1/4000, and you're shooting at 24 fps, it might look like hell, but why not?

    My question is about minimum slow shutter speeds: what is the slowest you can go, and does it depend on frame rate.
     
  7. RobWatson

    RobWatson Mu-43 Hall of Famer

    Ah, well you nailed it ... just think for a sec about 1 sec shutter and 30 fps ... not possible. Reality is not to be trifled with.

    What you want is timelapse. Take 1000 images (at what ever shutter speed) then dump them into you fav video editor and output 30 fps vid and, viola, 30 fps at any old shutter speed. Easy as pie.

    If you want the camera to use moviemode to shoot timelapse ... well, you need to go into the camera making business and make it yourself. I never hard of such a camera unless it was custom build specifically for such a task.
     
  8. hypnomatt

    hypnomatt Mu-43 Regular

    149
    Nov 4, 2011
  9. RobWatson

    RobWatson Mu-43 Hall of Famer

    No relation between F stop and FPS.
     
  10. speedandstyle

    speedandstyle Mu-43 Hall of Famer

    Here is a good article on the subject!

    Video Camera Shutter vs Frame Rate

    In theory the shutter speed can not be slower than frame rate{ie at 30 fps the slowest shutter speed would be 1/30th of a second}. With film it absolutely cannot be but with video there are tricks that allow you to use a shutter speed that is slower. Only reason I can think of to do this would be to gain exposure if aperture and gain{ISO} have been exhausted.
     
  11. teddoman

    teddoman Mu-43 Regular

    191
    Mar 22, 2013
    nyc
    Yes, low light exposure is one of the reasons I was thinking of when I asked this question.

    For shutter speed to fall below fps, you'd have to basically have overlapping exposures, I'm guessing.

    For example, if you're at 60 fps and set a 1/30 shutter speed, then to get 60 fps, you'd have to actually shoot 60 exposures a second at 1/60 but somehow digitally be able to combine two exposures into a 1/30 exposure. Not sure how that kind of digital magic works though but I guess it could be the same thing that is done with stacking or HDR.

    So the first frame at 60 fps would be exposures 1 and 2 (both 1/60 in length) stacked together, the second frame would be exposures 2 and 3 (both 1/60 in length) stacked together, etc. Essentially, you'd still be shooting using fps as your minimum shutter speed, but using stacking to give each frame the appearance of an exposure done at a longer shutter speed.

    If this is the underlying method, though, this will not solve the low light problem, as stacking two underexposed photos will still result in a merged underexposed photo.
     
  12. speedandstyle

    speedandstyle Mu-43 Hall of Famer

    Exactly how they make it work, I don't know but some camera will allow it. I figure they use extra gain or boost rather to compensate. However I usually never mess with the shutter speed. I just adjust the aperture and/or gain{ISO} or add more light to the scene. On movie sets 99% of the time they adjust the lights not the camera settings.