Using Zebra exposure tool

[scott william]

Is anyone using zebra exposure tool?

Can someone tell me how to set it. i don't understand the high IRE and Low IRE. I'd like to set zebra 1 at 70 for skin tones and zebra 2 at 100 for clip.

I set Zebra 2 at high IRE 100 but nothing clips, don't see any zebra at all, what should i set the Low IRE at?

 

[Noel R.]

Those are your brackets, if you want your highs to clip at 100 you will set your low to 100, and your high to a value greater than 100 for zebra 1 or 2. If you want your skin tones set at 70 you need to bracket it, for instance you could set your low to 65 and your high at 75, then you will see zebra on those values, 70 will be right in the middle.

 

[Daniel S Williams]

I believe the Red records ultra whites above 100 IRE up to around 109 IRE. Those levels are reserved for specular highlights, etc, and can be recovered in color correction by reducing the white level. This is assuming you're within the rec709 Spec

 

[Wey Wang]

I almost primarily use the zebra tools.

Zebra 1- High: 109, Low: 97
Zebra 2- High: 47, Low: 44

With this setup, I can instantly see where my highlights stick going super white and where my 18% grey is. When exposing skin tones, I try to have Zebra 2 on the face where I want my exposure level to be. This is really helpful in the off times when you have to iris rack because you're moving in and out of shadow or a cloud passes overhead.

 

[Trent Lillehaugen]

Please keep in mind that the zebra tool is operating on the "cooked" video out data rather than the raw data.

 

[John Brawley]

Zebra is kind of "broken" now because it no longer behaves the way a Zebra would be expected to on any other camera.

I haven't tried it recently, but I used to like to have a zebra at 102-109 but that doesn't seem to work anymore. You can get zebras to indicate at about 97 and up, but the upper range doesn't seem to work above 100. And it's behavior also changes depending on the ISO you have set, which is also kind of misleading.

I'm On a RED EPIC show now and I had a quick look again in Pre, but it still seems to behave this way.

From memory you can't set a Zebra of 102-109 and have it zebra even when you clearly are exposing in that range (except maybe at ISO 320 ?)

I think the reason for this was that the HDSDI output, in order to be LEGAL had to have a clamped white point.

I'm not in front of a camera right now, so I can't recall, but that's where it was at last time I gave up

jb