shutter speed

shutter speed is the length of a time the camera shutter is open, exposing light onto the camera sensor. the shutter speed should be at 1/50 when recording at 24 or 25 frames per second. 

using a higher shutter speed means more light will be captured in your image. whereas using a lower shutter speed means less light will be captured so your image will be darker. 

shutter speed also can be used to prevent blur. motion blur occurs when using a low shutter speed and having a moving object/subject like when shooting sports. anything that moves when an image is being taken will blur when the shutter is open. to avoid blur, the shutter speed should match the speed of what you're shooting. 

references:

https://www.creativelive.com/photography-guides/what-is-shutter-speed

the shutter speed used here is 1/30. in this clip, it is clear that a low shutter speed was used as the fan is slightly blurred. using a low shutter speed of 1/30 means that it takes longer for the shutter to close, this allows more light to be exposed. because the fan is moving, the long shutter speed will create motion blur when the shutter is open. 

the shutter speed used here is 1/50. by using a slightly higher shutter speed in this clip, parts of the fan are more visible and clear to see than the last clip. there is only a slight motion blur as the shutter is open because the shutter speed isn't high enough for it to be completely clear.

the shutter speed used here is 1/250. this clip is the most clear because of the high shutter speed. there is no motion blur in the fan, allowing us to see it better. because of the high shutter speed, blur is prevented leaving the video to be sharp.