LED flicker on video cameras is a subject that has been coming up a lot recently in my office. The major question is "is this flicker free?" Below I have outlined three popular methods of dimming LEDs and their affect on video cameras.
Constant Current Reduction (CCR)
In this scenario, Direct Current (DC) is being applied to the LEDs. The current is controlled so that a reduction will lower the output of the LEDs. There is no rapid switching of the current here, rather it is being throttled down by the driver. The camera will only see the difference in intensity, and will not flicker as the LEDs are constantly on, just at a lower current.
Pulse Width Modulation (PWM)
Unlike CCR, PWM switches the current being sent to the LED on and off at a frequency depending on the dimming level. This way, it appears to the eye to be dimmer by being switched on and off at a fast rate. The downside to this is that if the cycle is similar to the frame rate of the camera, flickering will occur.
0-10v Dimming (0-10v)
As long as the power coming to the LEDs from the driver is DC, there should be no issue with flickering. The factor here is the current type, Alternating Current (AC) fluctuates the current in a sine wave, where as DC has an output of a steady current. The camera will see the current fluctuating in the AC powered LEDs. Please note that I am referring to the current that is in between the driver and LEDs, not the power coming into the driver.
