I find it annoying when I want to Record at 60FPS but the Video is Sooo Dark. It makes it unwatchable.
In: Technology
* Imagine you little cousin Roger was throwing pennies at you.
* Imagine he could do this with super human speed.
* We’re talking 1000 pennies a second.
* Twenty-four times a second you stick all the pennies you’ve caught into a cup.
* Those cups would have a *lot* of pennies.
* But if you started sticking them in the cup 60 times a second…each cup would have far fewer pennies.
* This is the same thing happening with your pictures.
* For a given set of circumstances, a fixed amount of light hits your camera sensor every second.
* If you capture that every 24ths of a second, each capture gets a certain amount.
* If you capture every 60th of a second in stead, then each capture gets less photons hitting it.
a camera works by capturing light. The higher the frame rate the less light is allowed to reach the camera sensor resulting in a darker picture.
Videos are made of a lot of still “pictures” (also called frames), that are taken very quickly and played back fast enough to fool the eye into seeing it as movement. The setting on the camera that controls the number of these pictures that are taken per second is called “shutter speed” and it is measured in “FPS” which stands for frames per second, also known as “frame rate”. The setting that looks most normal to the eye for capturing movement is usually between 24-30 frames per second. The brightness (also called “exposure”) of each of those “pictures” is determined by three factors which affect how much light hits the sensor of your camera or how sensitive your camera’s sensor is to light. These factors are 1. How wide your lens is open (lenses open wider let in more light and make the picture brighter) 2. How long your lens is open to take each picture (the longer your lens is open the more light that can come in) and 3. The sensitivity of your camera’s sensor to light ( this setting is sometimes called iso) the more sensitive the sensor is the brighter the image will be when the other two variables are the same. For your question the important consideration is number 2, the length of time the shutter is open. To go from normal video at 24-30 frames per second to 60 FPS the shutter can only be open half as long, so you are getting half as much light on each picture if nothing else changes. So the picture looks darker. The faster the “frame rate” the less time the shutter is open and the darker the pictures/frames will be. You can brighten the image by making the lens open wider (this is controlled by a confusing setting called f-stop, where the smaller the f-stop value is the larger the aperture is so small f-stop values are larger apertures; and even more confusing on video lenses the f-stop is often replaced with a T-stop which works the same as f-stop but is just a more accurate measure of how much light the lens lets through to the sensor). You can also brighten the image by increasing the iso setting (also referred to as gain). This makes the sensor show a brighter image for the same amount of light that hits it. The downside of this is the increased sensitivity of the camera sensor causes something called “noise” to show up in the video that makes the quality of each picture a little worse. It doesn’t make a big difference at low settings (usually up to 800 or so) but at higher settings the noise gets bad (more expensive cameras especially ones with bigger sensors have less noise at higher iso). In a controlled environment often the best way to combat the darkening effect of increasing the frame rate is to add more light. If you turn up the brightness of any lights you are using to light the scene then more light will hit the sensor at the same iso, shutter speed and aperture.
A digital video is a series of still images. At 30fps, each image gathers light for 1/30th of a second. At 60fps, it gathers light for 1/60th, so it gets only half the amount of light per image, and so on.
Because by increasing the speed at which frames are captured, this is less and less time for the capture of the light that comprises the image. The same is true of shutter speed in photography.
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