Filming LED Displays

[mrbill762]

While filming in a radio station we found that the LED displays were rotating rather than static.

Thus you could not read the display you just saw a kaleidoscope of individual LED segments. Is there a way to avoid this in the future?

Thank you.

 

Mr. Bill

[Rob Belics]

LED and some other displays are not always constantly on as you have found out. It is controlled by the microprocessor usually and saves power by strobing them. The rate of "on time" varies but, IIRC, there is a minimum amount they need to stay on else they'll get too dim. So the brighter, the more "on time" there is.

 

I'm posting this FYI. I used to design electronic equipment. Others would no more how to solve the problem.

[mrbill762]

LED and some other displays are not always constantly on as you have found out. It is controlled by the microprocessor usually and saves power by strobing them. The rate of "on time" varies but, IIRC, there is a minimum amount they need to stay on else they'll get too dim. So the brighter, the more "on time" there is.

 

I'm posting this FYI. I used to design electronic equipment. Others would no more how to solve the problem.

Rob,

 

Thank you.

I thought it would be something like what you described.

I happen to have come across a movie with a radio station scene last night.

They dealt with it by blurring out the LEDs.

Most likely, in post as the rest of the board was in focus.

Thanks again for the reply and the education.

 

Mr. Bill

[Mitch Gross]

It depends on your video camera, but sometimes altering your electronic shutter can help with this problem. Most video cameras can only go to a faster shutter than the frequency of the camera, meaning that if you are shooting standard 60i NTSC in the US then your slowest shutter will be 1/60th. Going to faster shutter speeds may just make the problem worse, but it may also reduce the pulsing effect. You need to use the fine-adjustment for alterring shutter (called Synchro Scan or Clear Scan or whatever depending on the camera brand) to find the best speed for the situation.

[mrbill762]

It depends on your video camera, but sometimes altering your electronic shutter can help with this problem. Most video cameras can only go to a faster shutter than the frequency of the camera, meaning that if you are shooting standard 60i NTSC in the US then your slowest shutter will be 1/60th. Going to faster shutter speeds may just make the problem worse, but it may also reduce the pulsing effect. You need to use the fine-adjustment for alterring shutter (called Synchro Scan or Clear Scan or whatever depending on the camera brand) to find the best speed for the situation.

Mitch,

 

The camera was a Sony DSR-250

I know it goes down to 1/30 of a second.

I will check on Synchro Scan or Clear Scan that you mentioned for next time.

We only had a couple of hours in the stations studio.

So we just shot around the LED displays.

Thanks for the reply.

 

Mr. Bill

[Manu Anand]

Enountered this problem once while shooting an alphanumeric LEd display(it was ancient) and unfortunately no amount of playing with the clear scan let us remove the kaleidoscope effect.

 

here are some links that should be helpful in understanding how LED display technology works.

the first link is a glossary of terms often used when discussing LED tech stuff

 

http://www.chadmark.com/dictiona.htm

 

the second site throws some light on how they work and how new LED display are being designed to ensure that they can be shot on video without a problem.

 

http://www.phpcom.com/Pages/led.html

 

Manu

New Delhi

[mrbill762]

Manu,

 

Thank you.

I am off to get an education. :D

 

Thanks to all again.

 

Mr. Bill