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Is false colour for e.g. on a Flanders Monitor translatable to F/Stops or Lux?

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Trying to see if there is a way to analyze a reference image on a flanders monitor with false colour and then be able to estimate what f stop I need my lights at to replicate the image on set.

I can see that sentence taken a couple of ways so to elaborate, I would throw a reference image that I'm trying to replicate from my computer up on a flanders monitor. I would then put false colour on to see all the values. When on set I could try to replicate the lighting and I would know what values to place my lights at based on the false colour from the reference image. 

I'm wondering if there's a way to translate that false colour reading of shadows, highlights, middle into a value I can use on my light meter. The reason being is so that I don't have to wait for camera and monitor to be up before I start lighting, I can just use my light meter.

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I believe this subject was already covered in a post here: How does IRE correspond to exposure.

This image below is the legend for Flanders false color. Image taken from Shane Hurlbut's Academy. So that will help decipher the IRE values of what's on the image.

You can find out for certain yourself (highly recommended), by doing some tests with your specific camera, a white card, and a light (with scrims) in a dark room. Scrims are easy here because they are pre-measured to cut a half (single scrim) or full stop (double scrim). From this point, light the card and meter, then note the false color. Scrim the light and meter, then note the false color. Keep doing this, notating the IRE levels that each half/full stop registers on the monitor's false color. Then you will have your answer.

You have successfully cataloged the IRE relationship between that specific camera's image and monitor model. The false color IRE values on an Atomos or SmallHD will each be different. Same with using another model camera, say cataloging with a Sony F55 then switching to a Red Epic on shoot day.

This sounds like a lot of math, and I'm uncertain how much half stop increments will display in false color. So it may end up getting you only sorta there.

flanders false color.JPG

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On 8/30/2020 at 11:39 AM, Stephen Sanchez said:

I believe this subject was already covered in a post here: How does IRE correspond to exposure.

This image below is the legend for Flanders false color. Image taken from Shane Hurlbut's Academy. So that will help decipher the IRE values of what's on the image.

You can find out for certain yourself (highly recommended), by doing some tests with your specific camera, a white card, and a light (with scrims) in a dark room. Scrims are easy here because they are pre-measured to cut a half (single scrim) or full stop (double scrim). From this point, light the card and meter, then note the false color. Scrim the light and meter, then note the false color. Keep doing this, notating the IRE levels that each half/full stop registers on the monitor's false color. Then you will have your answer.

You have successfully cataloged the IRE relationship between that specific camera's image and monitor model. The false color IRE values on an Atomos or SmallHD will each be different. Same with using another model camera, say cataloging with a Sony F55 then switching to a Red Epic on shoot day.

This sounds like a lot of math, and I'm uncertain how much half stop increments will display in false color. So it may end up getting you only sorta there.

flanders false color.JPG

Thanks! It shouldn't matter what fps or aputure I shoot at either right the false colour values will be the same? ISO might matter though?

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This is fraught with uncertainty. You could work out some sort of relationship for a particular camera, with a particular luminance encoding selected, at a specific sensitivity, on a monitor with appropriate LUTs installed. Change anything and it's likely to become inaccurate.

I'd counsel against trying to do this. It's possible, but it's not clear to me how useful it would be, and it would be unreliable in the face of all kinds of tiny changes.

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I think, that if there will be a color grade applied to the footage, then it’s a little crazy to try to exactly match the exposure.

i think you can accomplish a good match, lighting by eye. The direction and lighting ratio should be similar, but that’s all that’s necessary.

You could make a good quality paper print of the scene already shot and refer to it as you work if that gives you more confidence. You might even grab still frames and put them up, side by side on your display with the live camera image, but you might need to take a computer with you on set to play back the still frames.

For me, in general, I find “false colors” a difficult tool to judge what I’m doing, and I’d rather look at clean image and a waveform.

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I never use false color, unless it's to check for flickering lamps. Like Bruce, I'd much rather look at a clean image and use a waveform to check shadows and highlights.

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