The output framerate of a video camera determines the amount of time that each frame can be exposed to light.
If the video output is set to 60 frames per second, that means that each frame is 1/60th of one second long, 16.67 milliseconds.
If you have a look in the settings of an Avonic camera, you'll find a range of options for the shutter to be set. Key point is to remember that some settings have no effect and others have a dramatic effect on the video output character, this all depends on the setting of the video output framerate.
Shutter setting in fraction of a second Necessary Exposure time in milliseconds
Amount of frames put out per second Time per frame in milliseconds
Now, if you have a closer look at the two tables above, you can see that some combinations are not possible simply, because a specific shutter setting may take more time than there is available in a frame.
If the video output is set to 60 frames per second, this means that each frame is 16.67ms long. Any shutter setting that needs more time than that 16.67ms, is useless because there is no more time in the frame.
Therefor, when 60fps is selected, 1/50th, 1/30th and 1/35th shutter settings have no function.
This phenomenon also works the other way around and can be used to your advantage: if the camera must be used in challenging light settings, the user can opt to set the output framerate to a lower framerate of let's say 50 frames per second. The length of each frame is now 20% longer when compared to to 60 fps, leaving more time for the sensor to be lit. In the case of an output 50fps, each frame is 20ms leaving room to use the shutter setting of 1/50th of a second.
If more exposure time is necessary, it is possible to lower the framerate further, however lowering the output framerate and lenghtening the exposure time per frame may lead to some (unwanted) motion blur. Theoretically, you can set the output to 25fps and have an exposure time per frame of 40 ms, that is approximately 2.5x more exposure time per frame than is possible on 60 frames per second