RED Build 30 is a step backwards

[Charles Angus]

On M-X sensor

ISO 800 = Set Zebra LO to 99
ISO 320 = Set Zebra LO to 96

Now, you've matched the Exposure Mode clipping indicator and the Zebra. You have your indicator while live shooting and you don't have to go into black and white mode.

This seems pretty clear - what's the problem?

Just figure out where the RedColour zebras match the true RAW clipping, and you're away to the races.

What's the problem?

 

[John Brawley]

This seems pretty clear - what's the problem?

Just figure out where the RedColour zebras match the true RAW clipping, and you're away to the races.

What's the problem?

Thanks for your helpful advice Charlie. Setting the LO to 96 to match clipping in RAW doesn't change how the zebra works in redcolour.

jb

 

[Mike Gross]

Thanks for your helpful advice Charlie. Setting the LO to 96 to match clipping in RAW doesn't change how the zebra works in redcolour.

jb

When I set zerbras to 96 in red color, it indicates the clipping for me. Isn't that what you're trying to do? have the zebras show where it's clipping?

Best I can guess is that there's a more film like shoulder in build 30 and the zebras need to be adjusted to how much shoulder zone at the very top end you want to be your clipping indicator.

I set mine to match the red on the exposure overlay and it works for seeing clipping with the color image nicely.

 

[Stuart English]

Zebras and False color

Zebras and False color

John, Matthew. We have two different arguments going on here so lets separate these out.

Matthew, we'll put your discussion on Video false color on hold for now. O.K?



John. You want a Zebra overlay to act as a clip indicator, you would rather use that than the Exposure false color.

O.K At ISO 800 the Zebra 1 LO value is 99. If you now enable Zebra 1 and Exposure false color, do those areas align when you push into clip?


If they do, then you can turn off Exposure false color and use Zebra 1.

 

[Tom Gleeson]

A man is not an island

A man is not an island

Johns concern over the accuracy and efficacy of Zebras in Build 30 is indicative of many camera people. Zebras are an easily understood industry standard exposure control that allows operators to check exposure while seeing the full photographed video image while a shot is in progress.

I embrace the new exposure methodologies as they are all valuable but an accurate zebra exposure is invaluable.

As a note while discussing this issue its probably best to indicate if the advice relates to MX or M sensor. In a perfect world I could switch in the menus for the zebras to either read the RAW or RGB.

Tom Gleeson DOP

 

[John Brawley]

John. You want a Zebra overlay to act as a clip indicator, you would rather use that than the Exposure false color.

O.K At ISO 800 the Zebra 1 LO value is 99. If you now enable Zebra 1 and Exposure false color, do those areas align when you push into clip?


If they do, then you can turn off Exposure false color and use Zebra 1.

I'm on an M camera. So I have set the camera to 320, and looking in redcolour, I can match the zebra overlay to exposure check at LO 98.

Strangely though, the zebra's grow larger (than clip) once I go back to RAW. Which also makes me question how true the 98 ZEBRAS are in redcolour.

So it seems 98 is the new 108. Something that still makes no sense. Have I been cheated of 10 IRE ? Is the 108 just now remapped (compressed) to 98 ? Eitherway it's illogical. (yes I know 108 was never legal, but again we're making informed decisions when we set a zebra that can go that high)


jb

 

[Mike Gross]

IRE doesn't mean much for raw which is where the confusion might be. Since you're looking at a pretty picture representation with redcolor, the zebras should need to be adjusted from the raw because of the contrast/gamma curve being put on the image.

 

[Martin Weiss]

I think it would be a great help if someone at RED could make a quick video on how to set-up and expose properly under build 30, including how to monitor exposure changes while recording.

 

[Antony M]

Ok, so what you want is raw zebras, right?

Graeme

Hell, yes!!!

 

[Graeme Nattress]

Hell, yes!!!

Don't know if that's possible though - it was hard enough to get the raw check false color in and with that I had a few more tricks up my sleeve to play with.

Graeme

 

[John Brawley]

IRE doesn't mean much for raw which is where the confusion might be. Since you're looking at a pretty picture representation with redcolor, the zebras should need to be adjusted from the raw because of the contrast/gamma curve being put on the image.

This is whats so misleading about all this. It seems to be IRE when you're looking lower down the scale but then it changes once you get up towards 100, never quite getting there. It's lost all it's meaning, yet its still described as IRE. (0-108)

jb

 

[Nick Shaw]

But since REDs post tools (and others that use the SDK) work with image values in the range 0-1, ie max out at 100% IRE, it makes sense for me that the HD-SDI output of the camera would also max out at 100% IRE. I always found it odd that before build 30 the HD-SDI output of the camera went above 100% IRE, which could never be reproduced in post.

If you look at the REDcolor HD-SDI output of the camera on a scope, and then look at the same image on the HD-SDI output of a RED Rocket, they match more closely than they ever did before build 30. This can surely only be a good thing. I gather that hardware limitations on the RED One mean they can never match precisely (as the output is only intended to be treated as a video assist). I hope on Epic they will match precisely.

 

[Stuart English]

Zebras and sensor clip

Zebras and sensor clip

I'm on an M camera. So I have set the camera to 320, and looking in redcolour, I can match the zebra overlay to exposure check at LO 98.

O.K. then you are good to go with that value for ISO320.

Strangely though, the zebra's grow larger (than clip) once I go back to RAW. Which also makes me question how true the 98 ZEBRAS are in redcolor.

Trust REDcolor John, its what everything is calibrated to under B30.

So it seems 98 is the new 108. Have I been cheated of 10 IRE ? Is the 108 just now remapped (compressed) to 98 ?

No you have not "lost" 10 IRE, REDcolor uses a different LUT (i.e. FLUT) compared to REDspace, and yes is rolling off your RGB highlights off.



Summary:

With M-X (which defaults to ISO 800 and LO=99) Zebra 1 already aligns to the onset of sensor clip.

With M, (which defaults to ISO 320 and LO=99) we might need to adjust the default to LO = 98.

If you are on an M camera give that a test, the LO value will be maintained across power cycles.

 

[Rob Ruffo]

You may be happy with the "only ISO320" work around, and I'm happy with the "rest of the image is black and white" work around. It's also more accurate than before. Balancing these things to get a camera who's architecture was not designed to do the things that today we want it to do is a very tricky task.

Now, it sounds to me that we need to take another look at how zebras are or are not working. They don't need to be referencing RAW for your needs - they just need to indicate clipping at ISO320. Is that right?

Graeme

I too would love an indication of clip/noise floor over a color image, along with the ability to get this and focus-peaking together (not choose 1, then the other), again over a color image. Seeing color while shooting is, well, useful. I don't mind of peaking and clip use the same red (or one could use purple) I can tell what is normal image and what is an indicator - I don't want/need everything else to be black and white. This is how it works in most other cameras, and it works perfectly (and I'd venture most people prefer it).

I'd also LOVE to have this Raw exposure clip/noise floor overlay to be assignable to a user-button for on/off with one click.

Anyone else with me on all this?

 

[Rob Ruffo]

I think it would be a great help if someone at RED could make a quick video on how to set-up and expose properly under build 30, including how to monitor exposure changes while recording.

+1

+1 again

I'd also love it if docs of any new build had a 1st page called "New Features" that would explain only what was new, so I don;t have to hunt through what I already know or even print the other pages.

 

[conrad gaunt]

Don't know if that's possible though - it was hard enough to get the raw check false color in and with that I had a few more tricks up my sleeve to play with.

Graeme

I have, as yet, not tried build30 at all, but could part of the answer be to only process zebras on 75% or even just the middle 50% of the image be a potential solution if horse power is an issue?

 

[Stuart English]

Zebras and sensor clip

Zebras and sensor clip

I suggest that there is a time out on the discussion until the debaters here have had a chance to adjust Zebra to 98 and check at various ISO's. Once that is done, we'll have a common base for further discussion.

We risk losing sight of the original question which was - how do you use Zebra to indicate clip?

 

[John Brawley]

We risk losing sight of the original question which was - how do you use Zebra to indicate clip?

Stuart I'll take your word for it if you tell me that LO 98 on my M camera @320 is going to indicate near sensor clipping whilst rolling.

But to extrapolate down from that new way you have of looking at zebra...

It seems you've somehow made the zebra... logarithmic ??? ....or it's now behaving in that way at the top end. I don't have a camera in front of me to check, but 50% seemed to be still 50 IRE.

70% still seemed to be 70 IRE. But now anything from 108 down to 98 is represented by just 98.

I think there's two issues. Knowing where sensor clipping is occurring whilst shooting in redcolour, and the apparent non-liniarity of the zebra.

Firstly, you need to massively re-educate users who will be expecting to be able to set a zebra @ 98 + and have it work @ 320 the way it used to and i might add the way it works with every other camera. I'd seriously reconsider not even allowing a user to set a zebra at 108 when it's not going to even work in redcolour anyway.

Because right now, there's no zebra at all ever if you do that. That seems like a bug. (even though i understand why it rolls off)

Because we all know that superwhite or 100+ ire isn't really useable, it's very useful as an exposure guide, because I can still have a zebra trigger at a predetermined superwhite value.

And Nick, I'm not sure which image is which, but your first image still shows information above 100...

No offence mate, but you're sitting with a post perspective. We NEED that kind of info whilst shooting even if it's not useable later on. It's useable because it gives a sense of *degrees* of highlight clipping. I'm not expecting you to be able to recover any detail out of there.

If I set a zebra at +100 then it's a warning that I won't be able to recover that info. Now, I have to set at 98. You've forced me to *seemingly* set a lower zebra, unless as I've extrapolated, in redcolour it's now somehow gone log at the top end.

So there's no graduation in exposure indication if you like between 100 IRE now represented by 98 and 108 which is ALSO represented by 98. (well actually that doesn't even work in red colour either but you get my meaning)

Even though you've told me 98 is the new 108 it still feels like you've forced me to set a lower *warning* indicator. I want some things to *just* clip. I like having an indicator that was just above clip, that I could mathematically and reliably set myself.

You've focussed on making the video output recordable, probably because you're working on EPIC to be able to record the HD-SDI output. That's fine but this means you've brought post related issues into the acquisition side of things and the expensive of what was a logical and reliable form of exposure check.

Sorry guys but you still haven't convinced me that what you've done is still the wrong way to do this.

jb

 

[Stuart English]

Zebra and sesnor clip

Zebra and sesnor clip

John, best to give Zebra at 98 a test and prove it one way or the other to yourself.

And it's not a new way of working with Zebra, it's always been a binary indicator, i.e. it's either on or it's off.

The LO value that is that trigger. If that is 100 it's everything from 100 and up. If 98, its everything from 98 and up.

So the task is to align the LO value to sensor clip, even though the sensor will clip in RAW space and Zebra operates in RGB space.

That was true in Build 21 and it's true in Build 30. Although FLUT rolls off highlights and hence changes the use of multi-color, Zebra is only affected to the extent that the LO value changes a little from where it was before.

 

[John Brawley]

John, best to give Zebra at 98 a test and prove it one way or the other to yourself.

I have in the test bay. I can make 98 match up to what exposure check says is sensor clip @5000K / 320.

And it's not a new way of working with Zebra, it's always been a binary indicator, i.e. it's either on or it's off.

You're wrong. It is a new way of working because it goes up to 108 but nothing above 98 actually works in redcolour. And by adjusting the high value, i can determine an expoure range i want to have Zebra. Now i can't above clipping.

The LO value that is that trigger. If that is 100 it's everything from 100 and up. If 98, its everything from 98 and up.

If I set a low value of 99 and a high of 108, nothing will zebra in redcolour. Have you actually checked this ? It's only triggered by the single low value of 98. And that's because everything above 98 is now represented by 98.

So the task is to align the LO value to sensor clip, even though the sensor will clip in RAW space and Zebra operates in RGB space.

That was true in Build 21 and it's true in Build 30. Although FLUT rolls off highlights and hence changes the use of multi-color, Zebra is only affected to the extent that the LO value changes a little from where it was before.

Well you've just confessed to changing the way that every camera operator will expect a zebra to work. It's your choice to do so of course, but i guarantee you I won't be the only one to complain and be confused about this.

And it's not changed a little. Before I could set a LO value of 105 and a high of 108. Now it's 98 and ALL values above.

jb