Thread: Does a higher frame rate produce a sharper image?

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  1. #1 Does a higher frame rate produce a sharper image? 
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    My thinking is that when shooting at a higher frame rate there is less time for the light to expose the sensor or film plane... when more light exposes it produces a slight blurring or softer look, especially when there is movement.

    Is this correct?
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  2. #2  
    Moderator Phil Holland's Avatar
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    Combination of a lot of variables including subject matter.

    One of the more notable impacts of HFR is you are likely using a faster shutter speed. That combined with more frames per second can minimize the general impact of motion blur and lessen the gaps between frames.

    Our eyes actually see at a very high refresh rate, but there's also perceptual adaptation to motion as well as our brains filling in the gaps.

    Waving your hand in front of your face gives you a good idea of what "natural" motion blur appears as.

    Most 24 fps content is shot with a 180 degree or 1/48th shutter. HFR truly depends on the the desired project frame rate, but for 48-120fps content it's not uncommon for 1-48th through 1/240th to be used, sometimes even faster shutters. The faster shutter speed alluding to a potentially less blurred image and perhaps "sharper" image. I would actually say just a clearer/crisper image as resolving power has nothing to do with this.

    The light doesn't have anything to do with it if the exposures are matched the same. But as you mention, when there's movement it is the most apparent.
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  3. #3  
    Senior Member AndreeMarkefors's Avatar
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    Quote Originally Posted by Daniel Porto View Post
    Is this correct?
    No it isn't.

    Shoot 24 fps with a shutter of 1/200 and then 60 fps with a shutter of 1/48 and you'll see that your higher fps aren't sharper. So, this is the definitive answer to your question.

    You can make a faux argument about choosing 100 fps LEADS to a shutter of 1/200 because THE RULES say... but let me stop myself right there.

    As you reduce the time of exposure (shutter speed), you reduce motion blur from both from camera and subject movement. At some point, for all practical purposes, movement will be frozen. At what shutter speed this happens will of course be dependent on type fo motion from both camera and subject.

    And naturally, the sharpest frames would be produced with zero motion blur.
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  4. #4  
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    thanks for the replies i have some meditating to do...
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  5. #5  
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    I guess the right word is a 'clearer' image, less motion blur when shooting at a higher frame rate.

    I've been playing around with some Phantom HD Gold 1000FPS clips, first sequence 3000% faster to simulate like shooting at 24fps and playing at 24fps. The 2nd sequence still shot at 1000FPS and playing at 25FPS

    One thing to mention is that when I re-rendered the slowmo with Davinci Resolve there was a strange bigger gap between frames in the final product. I dont have the studio version so maybe this is the reason why... so I pulled out my old macbook pro and used FCP6 to re-render and the footage was fine. Strange.

    Anyway if anyone is interested heres a old slomo video i made:
    https://www.youtube.com/watch?v=KS9QdhUAuEo&t=40s

    Edit: rendering the 1000FPS footage now and will post a link here later.
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  6. #6  
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  7. #7  
    Senior Member AndreeMarkefors's Avatar
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    I don't think you have any contradicting info in this thread.

    In almost all cases, when you increase fps, your shutter time decreases. So, higher fps mean "clearer" images.

    But it isn't the fps, is all I'm saying. It's the shutter speed.
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  8. #8  
    Best explanation I've ever read about what you can--and cannot--expect from HFR systems based on human imaging system: http://accidentalscientist.com/2014/...ny-valley.html
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  9. #9  
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    Thank you all very helpful :)
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  10. #10  
    Junior Member Trenton Massey's Avatar
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    When you slow HFR footage to normal speed (especially 60fps +), you're going to get a skinny shutter effect that seems crisper. But play back your HFR footage at 100% speed, you'll notice that it really isn't sharper. Definitely a trick of the eye. Your shutter controls that smear.
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