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Re: 動画撮影

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The simplest answer is that high frame rates allow for slowing footage down for slow motion effects. To record for slow motion, record in high frame rates (60fps, 120fps or 240fps) and then in an editor, reduce the playback to 24fps or 30fps.

Since shutter speed is dependent on fps, it also effects how long light can, or cannot expose on the image sensor in the camera. Higher fps take more images per second so the amount of time allowed for the camera to expose each image gets reduced. The higher the fps (60, 120, 240) the more light will be required to properly expose the image. Otherwise, it will get darker and/or possibly more blurry. When you slow down video, you generally want each frame to be very clear and without blur, so using a fast shutter combined with a high frame rate is important. The slower the shutter, the more motion blur that can be introduced in each image.

Now, to really go into detail and answer your question about slow motion, a little history about movies and videos is required. Originally, movies were recorded in 16fps. These old black and white movies didn't have live sound recorded to them and instead had subtitle cards displayed and would have music played over the entirety of the film. Latter, an analog sound-on-disc system called Vitaphone was developed to allow for syncing of the actors voices to the movie. To be able to sync properly, the film had to be recorded in 24fps. As technology developed, the cinema standard became recording at 24fps and is still considered more, "Cinematic" looking to many people.

TV and video changed the standard to 30fps. This is because of the US power standard, which uses Alternating Current cycles as 60 sine waves per second. Because of this, TVs were designed for screen updating every 30 frames or two fields of 15 frames each second. To get the best video image, video created for TV traditionally is recorded at 30fps.

You'll want to decide what frame rate you want to slow your video down to so you get your desired effect.

Now, with typical computer monitors having a refresh rate of 60Hz, and the latest gaming displays reaching all the way to 240Hz, higher frame rates can be used for even crisper and cleaner looking video. For this reason, many videos that are uploaded to online sources like YouTube use 60fps.

If you are mainly going to be watching your videos on TV or from a computer or mobile device, the 30 or 60 fps is best. If you want to record for cinema, then 24fps is generally accepted as the "most cinematic". Now, these are NTSC standards as apposed to PAL. NTSC is the format used in North America and a few other countries while PAL is the European standard that is used in most other countries outside of North America. For PAL countries, the equivalents are 24fps (for 24fps), 25fps(for 30fps), 50fps (for 60fps), 100fps (for 120fps) and 200fps (for 240fps). The right format for your region will help prevent flicker on video that was recorded indoors or under artificial light.

Your best option is to use a proper non-linear video editor. Some free options are:
VSDC on Windows-
DaVinci Resolve

You'll want to select a playback speed of somewhere in the 24fps-30fps range. If you need by percentage, these are safe slow motion settings.
240fps slowed by 25% - 10%
120fps slowed by 50% - 20%
60fps slowed by 50% - 40%
48fps slowed by 62.5% - 50%

You can also get slow motion by using a high frame rate and then editing using the GoPro Quik Mobile app. If you use high frame rates, the app will usually assumes you want it slowed down and in most cases will automatically do this for you. You can change the play back speed in the app to slower, normal, or faster if you wish.

I also suggest you read the following articles by a GoPro media developer (an actual GoPro employee who makes their videos, not some YouTube wanna be). Read these articles in this order even though they are not all specifically about your camera).