10-13-2018 05:52 AM
Re: Slo-mo help[ New ]
Ok, I'm going to give you a lot of information, but I'll try to make it as simple as possible.
First things first. Is your Macbook Pro – 2016 or newer? If so, you're all set. If not, then there are going to be extra steps or limitations to what you can do.
Your camera films in both HEVC and h.264. All that you really need to know about this, is HEVC is a newer format so only newer computers and operating systems can effectively handle it. (To learn more see this https://gopro.com/help/articles/block/hevc). Some of the resolutions and frame rates on your camera can only be filmed with HEVC (1080p/240fps being one of them). If your computer is unable to handle HEVC files, you should either not use those resolutions/frame rates, or convert them using Handbrake https://gopro.com/help/articles/how_to/how-to-convert-gopro-hevc-videos-to-h-264-using-handbrake
For editing, you can use a free editor like iMovie or DaVinci Resolve. Resolve is an amazing and professional editor, but the free version is limited to h.264 files so you will have to convert your HEVC files before using them in this program. YouTube is a great resource for learning how to edit so you should be able to find plenty of tutorials to teach you either one.
Now, when it comes to filming, before we can talk about Slow Motion, it's important to understand how the camera works and what settings do to change the way it looks. I'm only going to talk about those things specific to your GoPro camera (all of which can be accessed if you turn Protune ON). The options you have to decide upon are: Resolution, Aspect Ratio, Frame Rate, Shutter Speed, EV comp, ISO, WB, Sharpness, and Color (technically also bitrate by turning Protune ON or OFF). For the purpose of this post, I'm only going to go through Resolution, Aspect Ratio, Frame Rate, Shutter Speed, and ISO. I'll leave links at the bottom to a GoPro Media creator (helps make most of their GoPro videos) below so you can learn more about your camera and all of the settings.
Resolution: Basically this is represented by how many pixels your going to get in your video. This article does a pretty good job of explaining it in relationship to TVs http://4k.com/resolution/ You really don't need to be too concerned about the dimensions and how the resolutions get named. This isn't exactly accurate, but I like to just think of it as: 720p X 2 = 1440p and 1080p, but 1080p is shorter. 720p X 4 = 2.7K but 2.7K (4:3) is a lot taller. 720p X 5 = 4K and 4K (4:3) gives you everything. The higher the resolution the more pixels you get, but also the larger the file size.
Aspect Ratio: The Sensor in the camera is 4:3 square (technically not a square, but whatever). Since most TVs, Movies, and portable media devices (when turned sideways to landscape) use a 16:9 ratio (sideways rectangle), a portion of the picture recorded on the sensor is cut off. When you choose the 4:3 aspect ratio, as in 4K (4:3) you get the full sensor ratio (however, on playback on a 16:9 screen, you get black bars on either side of the picture because it has to be shrunk down to fit since it's taller. There are actually a lot of advantages to filming in (4:3) and you can easily make it work in a 16:9 format, but that's another long discussion for a much later day.
Frame Rate: OK, so now I'm finally getting to what your after! Frame Rate refers to how many "pictures" are taken by the camera every second (Pictures to Frames is not exactly an Apples to Apples comparison, but it's the basic concept). But, before I go further, I first (Oh No! another, "But First"), we have to briefly (whew) talk about playback. Most movies and videos that you watch are played back in one of three speeds: 24fps, 30fps (29.97), and 60fps. 24fps is considered by "media purest" to be the, "Most cinematic" and became the industry standard in 1927. It actually has more to do with the introduction "talking" movies as the technology developed away from silent pictures (which were usually filmed at 16fps). Most videos you watch are either 30fps or 60fps. The thing to keep in mind is, when slowing down videos, your target is going to be either 30fps or 24fps.
When you film, it doesn't matter if you film in 30fps or 240fps, when you play it back at regular speed it's going to look normal. However, if you take the video and put it into an editor, you can choose to have it playback at a slower speed. Since 30fps or 24fps is our target, we need to have filmed at a higher frame rate to slow it down (You can slow down video filmed at 30fps but no more than to 16fps which will make it look like it was shot with an old Standard 8 camera). Using 30fps as our target, 60fps can be slowed down in half (50%), 120fps one quarter (25%) and 240fps one eigth (12%). So, achieving smooth slow motion requires filming in the highest frame rate (240fps) and then, with a video editor, changing the video playback to a slower frame rate (30fps or 24fps).
Ok, so if it's that simple, why all this other stuff?
Well, because frame rate isn't the whole story in getting the "Best" picture and sometimes, even when you want "Super Slow Mo", 240fps isn't the best option.
Shutter Speed: This is something that a lot of people confuse with frame rate. They do share some properties, and shutter is dependent on the frame rate, but they are not the same. Frame rate is how many "Pictures" are taken in a second. Shutter Speed is how long each of those "pictures" is exposed for. For this example we will use 30fps. With 30fps, the camera is taking 30 "pictures" in one second. Although it's digital, it's easier to think of shutter speed as a physical shutter opening and closing. For every "Picture" the shutter can open for a maximum of 1/30th of a second. In other words, the shutter can stay open for the entirely of one of the 30 pictures, close and then open for the entirety of the second picture, close and continue doing this for all 30 pictures. If you change to 60fps, the shutter can now only stay open for half the time that it could for 30fps because now it has to open and close 60 times in one second.
Now, most of the time, in good lighting, the shutter actually exposes for a much shorter time and doesn't need the entire frame to expose. However, understanding shutter speed will help you understand why using a faster fps in low light will result in darker video. The shutter just doesn't get enough time to properly expose the "picture" because it has to move on quickly to the next frame.
Another important aspect of shutter speed is motion blur. If you wave your hand back and forth in front of your face with your fingers open it will be blurry. If you start blinking, really really fast, the blur starts to go away. When the shutter opens, the image begins to be "painted" onto the sensor in the camera. As long as the image doesn't move, the picture stays the same. However, if during that time that the picture is getting painted onto the sensor the subject moves, then that new position is also painted creating motion blur. If you are going to do super slow motion without any motion blur in each frame, you will also want to use the max shutter speed. The camera does a good job of this automatically, but setting this yourself is sometimes necessary to get the best shot. The max shutter speed for 30fps is 1/240 where the max for 240fps is 1/1920.
ISO: OK, so faster shutter and higher fps makes for awesome slow motion, but it also can result in very dark images. To compensate, the camera can enhance each pixel (give it more charge) by raising the ISO. ISO refers to sensitivity, but sensitivity is a term that is better used for actual film. In the digital camera, the higher ISO is more like pixel excitability. The higher the ISO, the more excited and bright the pixels get. Like children; however, the more excited they are, the more noise they make. This "noise" is also referred to as grain and results in somewhat blotchy and messy images when it's set too high. However, when the ISO is low, the pixels are dimmed and subdued. There is far less noise, but also far less brightness. In good light, a Low ISO is ideal. For faster shutters and higher fps and/or dim light, you want a higher ISO.
Getting the best slow motion shot is taking all of these things into consideration. You first have to look at your environment, second, imagine what would be a suitable result, and then third, make adjustments accordingly. For example, if I wanted to capture an awesome slow motion shot of my buddy jumping his truck off of a dune (we call it hucking) but the sky was overcast and gray, I might go with 120fps over 240fps so the image didn't get to dark and muddy. If I absolutely wanted the slowest video possible, then I'd go with 240fps, shutter 1/960 (I don't want cinematic motion blur) and then pump the ISO up just enough to keep the image bright but not too noisy.
If you have questions, feel free to ask!
Also check out these links to learn more about your camera and how to get the best shot (even if it's not about your camera model, there is good info in the articles that will help you out):