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Video Frame Rates & Shutter Speed

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Kelley Tuck
Video Frame Rates & Shutter Speed
on Sep 29, 2009 at 2:46:29 pm

Hi All,

I've been working with video for a long time, but only picking up things as I need them to 'get by' in a project. I'm now to the point where I really want to 'know that I know that I know' how certain things work rather than just guessing at it or making it work for the moment, etc.

The first thing I would really like to understand is how to use different frame rates and shutter speeds, and how using them in different ways gives the appearance of cinema, home movie, TV shows, etc. I realize that this thread post is probably not the best way to learn about this, as it can call for lengthy paragraphs and discussions. However, would anyone mind please pointing me to the best sources they have found for explaining frame rates and shutter speeds and how this affects the output of the final product?

I am the media director of a church in Roanoke, and when my pastors ask me to get something done for them, I want to know the best ways to translate what I see in my head to the camera, and eventually and ultimately, to the audience. Thank you!

Agape,
Kelley D. Tuck

“And so, since God in His mercy has given us this wonderful ministry, we never give up.”
2 Corinthians 4:1 (NLT)


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Todd Terry
Re: Video Frame Rates & Shutter Speed
on Sep 29, 2009 at 4:39:57 pm

It's a lot more complicated than I can write here, but here it is in a nutshell...

For about a century or so, most all film was shot at 24 frames per second. It still is today.

For most of it's life, most video (at least in the NTSC world) was shot at 30 frames per second, or 60i. The "i" means it is interlaced, each frame is made up of two fields, basically resulting in 60 pictures per second.

Ergo, video is very smooth, and film is a little more choppy and stuttery. Technically you might say then that as far as motion goes, video is better. But aesthetically, 24fps gives you some inherent drama that 60i misses.

The newer generation of cameras can shoot 24p, meaning rather than 60 interlaced fields per second, the camera shoots 24 progressive frames per second... just like a film camera. That gives the video a more filmic look.

Ok, that's frame rates. You also asked about shutter speeds.

"Normal" shutter speeds are typically about one-half of the frame rate. In a film camera shooting 24fps if the camera had a 180° shutter (which most don't, but close), then the shutter speed would be 1/48th of a second. Therefor, a "normal" shutter speed for a 24p video camera is also 1/48th. A normal shutter speed for 60i video would be 1/60th of a second, or one-half of its 30fps.

Motion images look "right" because there is motion blur. If you stop a video or film on a single frame, it is blurry (if there is action in the frame). Your eye and brain interpret this as normal motion. If you shoot with too slow a shutter speed (on either film or video) then the individual frames are too blurry, and things just don't look right. Conversely, if you shoot with too high a shutter speed, there is no motion blur on individual frames and when viewed at normal speed the images look choppy and stuttery.

Higher-than-normal shutters are often used in movies in action sequences, to make them look more... well... "actiony." Sometimes too much so. I couldn't even watch the movie "Gladiator," as all of the action/fighting scenes were shot with such a high choppy shutter that it was almost unwatchable. The effect was used with much greater success in "Saving Private Ryan."

Those are the very very basics. Others may have lots more to contribute, and there's plenty to read about both frame rates and shutter speeds in the ASC manual.


T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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Richard Herd
Re: Video Frame Rates & Shutter Speed
on Sep 29, 2009 at 10:04:50 pm

Here's a fine cow article that mentions a lot of important topics. http://magazine.creativecow.net/article/the-truth-about-2k-4k-the-future-of...

Here's a quote: "But we have to remember that 24 frames was never designed from an imaging standpoint. It was designed for sound."


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