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Old September 12th, 2012, 01:36 PM   #1
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"On air" lights - a question

Help me understand one thing. I haven't found an appropriate category for my question. I work at a local TV station, and when I can, I try to understand all of it's techical parts and mechanics. Seeing that language, lack of knowledge from me and the technical state of the place I work, I can't get an answer to something that started bugging me recently.
In portrayals of TV studios, from what I understand that is happening, I always see that a light turns on over the camera that is currently "on air", so that either the presenter or guests know at which camera to look at.

I would like to ask what is such a sistem called, and if any of you are familiar with it?
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Old September 12th, 2012, 02:33 PM   #2
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Re: "On air" lights - a question

Marius, salutari din Atlanta de la un Targu Muresean.

Those light are called tally lights and they work off of the video switch; the switch (mixer) sends a signal to the LED light on the camera when that camera is live. Google "tally light" for more. More complex systems come with tally lights, you can also add them later, provided the mixer has the appropriate driver.

tally lights | B&H Photo Video

I hope this helps,
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Old September 12th, 2012, 02:42 PM   #3
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Re: "On air" lights - a question

Mulțumesc ! :)
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Old September 13th, 2012, 02:36 AM   #4
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Re: "On air" lights - a question

Hi Marius, just about all the prosumer and some consumer video cameras have on board 'record' tally lights as well,
some switchable on-off in the cams menu.

Many folk leave them turned them off, to avoid drawing attention to the camera outdoors or un-nerving the talent.

Cheers.
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Old September 13th, 2012, 03:32 AM   #5
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Re: "On air" lights - a question

Most pro cameras actually have two tally lights ..one front and one back and you can have back, front, both or none enabled...As Allan says I usually run the back tally and leave the front off as I'm shooting solo with two cameras..it's reassuring to be able to see the back tally light bright red and know at least that you haven't forgotten to press record on the camera..while the absence of the front tally doesn't put your subject off!! In fact I was recording a wedding a while back and couldn't figure out why the bride's snow white dress had a red dot on it!!! My front tally was on, so now I just run the rear light so I know what state the camera is in!!

Chris
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Old September 13th, 2012, 04:32 AM   #6
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Re: "On air" lights - a question

One of my student projects years ago was to design a tally light circuit for a mixer that didn't have it as standard. The basics were pretty simply - you took a +volt feed from something like the button light, and then used that to switch a semiconductor, through a resistor so it had no impact on the device - sort of 'sniffing' the voltage across the led/lamp. I remember the satisfaction at putting a few handfuls of bits together so it worked. Then I had the problem that the mixer had two rows of buttons, and the top one or the bottom one could be the live one, so the next design had to deal with which set was active and it suddenly got more complicated. They actually sell single units that can do this for radio stations (Canford Audio) so a light comes on outside the door when the fader on the mixer is open. Exactly the same system.

There are some commercial systems available that have little LEDs you tape under the lens and inside the viewfinder because tally lights are really, really important.
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