6K Pro 2nd Native ISO at 1250 not 3200?

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MartinVidic

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6K Pro 2nd Native ISO at 1250 not 3200?

PostFri Jun 02, 2023 4:42 am

So when I increase focus peaking to 100%, i can also see the peaking in noisy areas of the image.

And then, when I increase the ISO slowly, i can see that noise jumps down when i reach 1250.

I read the second native ISO is at 3200 but is it really at 1250?
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Robert Niessner

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostFri Jun 02, 2023 5:16 am

The first gain stage starts at ISO 100, the second starts at ISO 1250. Native ISO is 400 for stage one and ISO 3200 for stage two. Remember: inbetween a stage changing ISO is just applying a different gamma curve.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostFri Jun 02, 2023 1:47 pm

When you go from 1000 to 1250 the position of middle grey drops about ~2.5 stops. The concept of a native ISO is based largely on what mfrs. consider an acceptable SNR. Lower ISOs will be less noisy in raw cameras because they assign more data below mid grey.

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostFri Jun 02, 2023 2:01 pm

Howard Roll wrote:Lower ISOs will be less noisy in raw cameras because they assign more data below mid grey.


At least with BMD cameras, it's useful to point out that this will only be true if exposing for middle-grey in all instances -- as in opening up the lens as the ISO is reduced. The ISO value itself, within either circuit, has no effect on noise or the exposure.

Any actual exposure difference would depend strictly on the f-stop.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostFri Jun 02, 2023 2:01 pm

I’ve shot the BMPCC4K with ISO 1250 several times, but switched to ISO 1600 for my last shoot in May. Rationale was that I still need to allow for capturing (okay displaying) more stops above middle grey. I thought the results were acceptable and less noisy than ISO 3200.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostFri Jun 02, 2023 2:04 pm

The reason 1250 or 1600 is less noisy than 3200 is because you're using a wider aperture at the lower ISOs to get the exposure. At the same f-stop, the shots at all three ISOs will be identical. They'll look different, but only because of the curve applied, which is [only] metadata for raw.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostFri Jun 02, 2023 4:41 pm

John Paines wrote:The ISO value itself, within either circuit, has no effect on noise

Dondidnod wrote:

"Thank you for a very informative read. I'm trying to wrap my head around one point regarding noise though.

"...if there is a bit too much noise at 3200 or that’s too much light, you can shoot lower. ISO 1600 or 1250, are likely going to produce better results in terms of noise compared to 3200""

Captainhook wrote:

"...(EDIT - So a couple of) the 3rd party cameras can't have highlight recovery as they clip the data on the camera etc before sending out, and most of them use mostly analog gain for ISO (being DSLRs) so ISO is not available either but you can still adjust exposure +/-5 stops so that doesn't matter."

Re: Sigma fp with BRAW and DNG

viewtopic.php?f=2&t=138074&p=743518&hilit=Braw+iso+doesn%27t+matter#p743518

So, if there is no analog gain in Blackmagic cameras, and no added noise as a result, if you are shooting in BRAW, does it matter what your ISO setting is within the upper range while shooting, since you can change it in post?

Captainhook wrote:

"Just for clarity my above quote was ".. some 3rd party cameras ..."
To the topic, the "digital" ISO settings in camera can also be thought of as another exposure tool - adding digital gain will still increase the apparent noise and in many cases more than "analog gain" which is why you might find more noise exposing for and using ISO1000 versus ISO1250 (the second "analog gain stage") on the Pockets.

So if you treat it like an exposure tool then changing digital ISO on camera and exposing for that will still have an effect on apparent noise. Yes you can change digital ISO in post but you have already decided on the amount of light hitting the sensor and that wont change, so if you want to under/over expose the sensor it helps to also monitor that way while shooting IMHO.
"Native ISO" in our case is what we have decided is a good trade off between apparent noise when exposed for that digital gain and the dynamic range distribution (not necessarily "even" distribution but what has been decided as 'acceptable' given the amount of noise etc). Its a recommendation for how to expose the sensor."

Re: ISO 6/23/22

viewtopic.php?f=2&t=162340&p=859997&hilit=+ETTR+Exposure+to+the+Right+of+the+Histogram%3A+#p859997
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostFri Jun 02, 2023 6:29 pm

I admit I could never quite wrap my head around why ISO 3200 is the "native" ISO of gain stage 2. If you have to shoot at 1250 or above, you're in a low-light environment. And in a low-light environment, you want to assign most stops below middle grey to keep the shadows clean.

For example, when shooting raw in a controlled environment in a Iow-light scene, say a hallway at night - I keep a low ISO of maybe 400 to get clean shadows. Then I light the scene based on that. So far so good because in a controlled environment, I'd never use the second gain stage anyways (because it just looks worse).

So let's say I don't have enough lights with me and I need to go to the second gain stage. ISO 1250 would be enough, I like the image. If I raise to 3200, it would be a bit overexposed and I'd either have to stop down or dim the lights.
Wouldn't I always want to stay in the lowest possible gain aka 1250? Because I'm still in a low-light environment. There's barely light. And I want to keep the shadows clean, so why would I raise it to ISO 3200? It's not like when you go to gain stage 2, suddenly more light hits the sensor.

Is the curve designed that there's more overall dynamic range at 3200 but barely more noise compared to 1250 or something like that?
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostFri Jun 02, 2023 7:16 pm

Again, with braw there is no analog or baked-in digital gain associated with increasing iso values within each circuit. For purposes of exposure, ISO 100 is the same as 1000 -- at the same f-stop. And 1250 is the same as 6400. Of course, a shot metered for 6400 will be whole lot noisier than one metered for 1250. But that's only because the two exposures will have a nearly 3-stop difference between them. Use the same aperture with both, and you'll get identical exposures (but different metadata curves). Highlights will clip at exactly the same point, and shadows will be crushed at the same level. And, measurable noise will be exactly the same (it may differ subjectively, based on the ISO metadata).
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostFri Jun 02, 2023 9:50 pm

Thanks John but I know all this. That's why I'm asking why gain stage 2 is rated "native" at ISO 3200 and why anyone would go there if exposure when rating at 1250 is good enough. If it's good at 1250 and I then go to the native ISO of 3200, I would have to stop the lens down, or dim the lights so that exposure is correct again (in preview). Which means I'm letting even less light hit the sensor. And I'm already in a low light situation. I just wonder why 3200 is rated "native" when in low light you should rather rate at a lower ISO, not a higher. Having to switch to 1250 and above by design means that it is a low light situation.

Maybe I am just completely misunderstanding the term "native". I thought it describes the recommended ISO for most/standard situations.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSat Jun 03, 2023 3:58 am

For most camera manufacturers, the term 'native' ISO means an equal distribution of steps above and below that value (BM is seeing it that way too, look for the charts).

But then, while hard clipping is clearly defined, it's disputable how far below you would define noise as 'tolerable' (not even considering NR here).

Consequently, it's up to you to rate your camera lower for cleaner shadows at the cost of less room for highlights.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSat Jun 03, 2023 7:55 am

Good point about hard clipping. Old charts rated the BMPCC4K only 2.3 stops above middle grey @1250, newer ones on their website though rate it at 3.8/8.5 (and 4.3/7.8 for the 6K). Also, is early red channel clipping still an issue with the pockets?

I guess rating 3200 native is a more sure shot to prevent clipping in certain low light situations. Say shooting a bonfire scene. Every time the flames would be in frame they probably clip hard @1250. But if nothing clips, I don't see a reason to raise ISO.

I was a RED owner over 10 years ago and learning to shoot raw was a thing as it was counter intuitive (lower ISO in low light, raise in bright environments) to many, including me. At that time, people often were advised to "just stick to the native ISO" ("native ISO" was a vogue expression back then). I guess I still suffer from that education.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSat Jun 03, 2023 11:39 am

It took me a long while to wrap my head around the concept and I can only explain it as I understand it.

The first ISO range comes off the sensor with no amplification "I'm guessing". This range is divided into 11 ISO steps ranging from 100 to 1000. ISO 400 has the greatest overall dynamic range. Middle grey is shifted up and down along the range digitally allowing the user to expose at different middle grey points along the spectrum creating different distribution of light across the exposure latitude above and below middle grey.

The second ISO range comes off a 4X light amplifier. The same process is repeated with 3200 ISO yielding the greatest overall dynamic range. The amplifier does introduce noise across this range but again the steps in the range appropriate more of the usable light in the shadows at lower settings giving the effect of less noise in the shadows via digital manipulation of the middle grey point.

All of this is subjective to the user as BM defines usable dynamic range and the user may not agree. At the end of the day for me, it was all about using the camera and understanding what to expect at different settings. All of the theory behind how it works is nice to know but eventually there was no need for me to reference that theory to get the exposure I was hoping for.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSat Jun 03, 2023 12:28 pm

Michel Rabe wrote:I'm asking why gain stage 2 is rated "native" at ISO 3200 and why anyone would go there if exposure when rating at 1250 is good enough. .


Exposing for the native ISO is deemed by the manufacturer to be the best compromise or balance between noise and dynamic range.

But if you can expose for 1250 and the stops are where you need them (for example, there's no problem with clipping), then of course that makes more sense, for that shot, since you'll have less noise.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSat Jun 03, 2023 1:10 pm

IMO BM totally messed up with this 'ISO' system. There are 2 gain stages and that's it. The rest should have been a separate control for 'brightness' or mid range lift in each stage and not called ISO at all. ISO is a legacy metric from the days of film and has little to do with digital or esp when non linear profiles are involved.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSat Jun 03, 2023 4:47 pm

Totally agree with John. As someone who professionally shot, developed, and printed film and paper for many years, this exposure system ain't that one.

The terms used confuse more than illuminate.

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSat Jun 03, 2023 4:59 pm

rNeil H wrote:The terms used confuse more than illuminate.


Proper exposure for 400ISO film is the same as 400ISO digital. What's confusing?

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSat Jun 03, 2023 5:24 pm

But exposing at 800'iso' on the BM is not the same as exposing 800iso film
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSat Jun 03, 2023 5:52 pm

How is it not? Middle grey is properly exposed the same for 800ISO film as it is 800ISO digital. The allocation over and under changes but the mid point is constant. Much like film, 800ISO is going to be noisier in the shadows. If you are proposing EI vs ISO, yeah maybe, but some arbitrary brightness slider, no thanks.

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSat Jun 03, 2023 6:00 pm

Fun Fact. When BM first released the BMCC and later the BMPCC they actually used the term ASA instead of ISO which would annoy me as well. I'd prefer it if they called their log curve LOG instead of film and their 709 curve 709 instead of Video so in part I get it.

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSat Jun 03, 2023 6:36 pm

I kinda liked ASA haha.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSat Jun 03, 2023 8:29 pm

Transparency always helps understanding. One of the reasons Video is not called 709 is that CaptainHook has mentioned in the past that Video is not exactly Rec.709 but has been tweaked by BMD.

At least the name of the optional Extended Video has more clarity in that it’s a look developed by BMD. I agree with others that the current implementation of Extended Video is excellent as of firmware 7.3 that I tested and found it to have improved colour and therefore better to judge your image in the camera.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSat Jun 03, 2023 9:18 pm

In my humble experience metering between 400, 800, whatever ISO does not directly equate to using film of differing ISO.

There's that whole thing of mid gray and stops over/under. Vastly different than simply choosing the film.

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSun Jun 04, 2023 1:47 am

Not that much.
With film you also tried to stay in the linear part of its curve and avoided the shoulder for important parts of the scene (the S-curve parts). And an underexposed film, like ASA/ISO 400 instead of 200 meant forced development, resulting in more grain.
What’s so fundamentally different?
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSun Jun 04, 2023 2:18 am

To me, like the other person posting above, the difference in the way the BM cameras change response to varying ISO settings, is not at all like metering and selecting a film of differing ISO to match the circumstances.

Nor does it seem to match push processing.

Under-exposing then over-processing the film wasn't very satisfactory in most cases. Although I did it at need many times over the years.

Depending on how much exposure drop and corresponding development push you did, it would slightly extend the toe and eventually eliminate the shoulder, so changing the contrast proportions of the image. True.

But I did very intentionally use the shape of the film's curves, it's toe and shadows shapes, to get the tonality I wanted in the image. How could you truly control the entire image if you didn't?

So I simply don't understand the comment about avoiding the toe and shoulder. I certainly, intentionally, used them.

But to my eye and scopes now, changes to ISO settings do not in any way result in the same changes that adjusted ISO settings did with film.

It took a fair amount of testing, for me to really grasp the differences and the use case for each setting. Which is not at all based on the available light appertaining to the scene.

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSun Jun 04, 2023 2:45 am

rNeil H wrote:But I did very intentionally use the shape of the film's curves, it's toe and shadows shapes, to get the tonality I wanted in the image. How could you truly control the entire image if you didn't?

So I simply don't understand the comment about avoiding the toe and shoulder. I certainly, intentionally, used them.


Sure, they could be used intentionally. But this is the area where the technologies are fundamentally different. There are no shoulders like for opto-chemical film, they need to be simulated. Electronic sensors are actually strictly linear (you could even see those linear images with some software for the early Red).

OTOH, the linear range of film was about 12 stops (according to Kodak not some fanboys of analog).

We got much more than that in professional cameras, and camera manufacturers try to record all of that in log to preserve it for post.

IMHO, it’s up to us to simulate those ‘cinematic’ shoulders in post. ARRI is obviously trying to establish something like such simulations in the new S-35 camera, and it might be an interesting feature request you could suggest to BM.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSun Jun 04, 2023 3:00 am

The linear range data for film varied dramatically by film stock and era. Most of my film work was 120/220 color negative, through late 70's up to 2001, and it most certainly did not have 12 stops useful range.

If our exposure was off by a third stop or more, it took careful work in printing to get close to a similar image as we "normally" produced. This was to get that all important 6 stop area, from deep but distinct shadows through diffuse highlights, correctly printed.

Matching the Adam's zones 3-8.

There were a stop or two of bits of deep darkness below the detailed shadows. And above the diffused highlights a couple stops of "feathered speculars".

But again, any improper exposure immediately reminded you to pay attention. As we handled our own lab work, being totally picky sots for image quality and consistency, we were very, very aware of exact exposure issues.

Perhaps the later color neg films made 12 stops of useful details. Nothing I worked with ever did.

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostSun Jun 04, 2023 3:25 am

Correct, Kodak claimed those for the most recent neg material.
And then, just like with digital, it’s subjective how far you’d want to go into the ‘less linear’ part of the curve.

Fun fact: film is actually digital and electronic sensors are analog. ;-)
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostMon Jun 05, 2023 11:09 am

Howard Roll wrote:How is it not? Middle grey is properly exposed the same for 800ISO film as it is 800ISO digital. The allocation over and under changes but the mid point is constant. Much like film, 800ISO is going to be noisier in the shadows. If you are proposing EI vs ISO, yeah maybe, but some arbitrary brightness slider, no thanks.

Good Luck
Changing ISO should be like changing aperture or shutter angle and change all tonal values by the same amount. Changing ISO in the BM cameras within each gain stage only changes the mid tone.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostMon Jun 05, 2023 10:00 pm

John Griffin wrote:Changing ISO should be like changing aperture or shutter angle and change all tonal values by the same amount. Changing ISO in the BM cameras within each gain stage only changes the mid tone.

That's not the case with Gen 5. For instance the ISO dropdown in the RAW panel is the same as the exposure slider. You can do an experiment, for example with a camera like the 12K start with say ISO 800 and exposure on 0 and grab a still, then change to ISO3200 and compensate with -2 on the exposure slider. Compare and they are exactly the same. Switch to Gen 4 and do the same experiment and yes they are different except the mid grey point.

This is also evident in that with Gen 5 we have a single log curve for all ISOs so there is only one equation to linearise from log that can be used for any ISO and any camera.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostMon Jun 05, 2023 10:45 pm

CaptainHook wrote:That's not the case with Gen 5. For instance the ISO dropdown in the RAW panel is the same as the exposure slider.
This is also evident in that with Gen 5 we have a single log curve for all ISOs so there is only one equation to linearise from log that can be used for any ISO and any camera.


I did notice that, great!
Side note, I also noticed that changing exposure of Braw footage (6K Pro) in the raw tab gets me cleaner, more punchy results than using Offset in the Primaries.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostTue Jun 06, 2023 8:47 am

CaptainHook wrote:
John Griffin wrote:Changing ISO should be like changing aperture or shutter angle and change all tonal values by the same amount. Changing ISO in the BM cameras within each gain stage only changes the mid tone.

That's not the case with Gen 5. For instance the ISO dropdown in the RAW panel is the same as the exposure slider. You can do an experiment, for example with a camera like the 12K start with say ISO 800 and exposure on 0 and grab a still, then change to ISO3200 and compensate with -2 on the exposure slider. Compare and they are exactly the same. Switch to Gen 4 and do the same experiment and yes they are different except the mid grey point.

This is also evident in that with Gen 5 we have a single log curve for all ISOs so there is only one equation to linearise from log that can be used for any ISO and any camera.

When I set my BMPCC6k to 100 ISO and expose for a highlight so it's just under clipping and the cycle the ISO up to 1000 the clipping point doesn't change but the image gets 'brighter' i.e the mid tones are boosted so how can it be a single log curve for all ISO's within a gain stage?
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostTue Jun 06, 2023 5:35 pm

Under gen 4, one stop changes of ISO and exposure in the raw tab did not produce identical results, because the curves differed slightly with different ISO values. Now they apparently don't.

I think(?) what happen in gen 5 is that the exposure and ISO settings have, stop for stop, the same effect on the footage.

But of course the image gets brighter as the ISO (or exposure) increases. It's just that now, they get brighter in the same way (I think).
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostTue Jun 06, 2023 11:00 pm

John Griffin wrote:When I set my BMPCC6k to 100 ISO and expose for a highlight so it's just under clipping and the cycle the ISO up to 1000 the clipping point doesn't change but the image gets 'brighter' i.e the mid tones are boosted so how can it be a single log curve for all ISO's within a gain stage?

What's your workflow with this observation? Is this on camera? If so, what's the record page dynamic range set to and how are you monitoring the clipping point?
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostWed Jun 07, 2023 9:22 am

This is on/in-camera. Using zebras to monitor the clipping point with the DR set to film.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostWed Jun 07, 2023 11:05 am

We scale the zebras (and false colour and histogram) depending on the ISO you're using on camera, so you will always see the clipping indicated for that ISO (otherwise you may be clipping the sensor but certain ISOs wouldn't tell you). Since it is the same underlying linear data, the clipping point will appear the same for each ISO in the same analog gain bank as it should.

(some may have seen I also pointed this out in the EL zone system thread)
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostWed Jun 07, 2023 11:57 am

CaptainHook wrote:Since it is the same underlying linear data, the clipping point will appear the same for each ISO in the same analog gain bank as it should.

Then this is not an ISO control but a 'brightness' control. A true ISO change shifts all the data up or down by the same amount just as a change of aperture or shutter angle does and just as adjusting 'offset' does in Resolve and also how ISO is implemented in film and other digital camera systems. What BM ISO does is more akin to a gamma change within each ISO.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostWed Jun 07, 2023 2:51 pm

John Griffin wrote:
CaptainHook wrote:Since it is the same underlying linear data, the clipping point will appear the same for each ISO in the same analog gain bank as it should.

Then this is not an ISO control but a 'brightness' control. A true ISO change shifts all the data up or down by the same amount just as a change of aperture or shutter angle does and just as adjusting 'offset' does in Resolve and also how ISO is implemented in film and other digital camera systems. What BM ISO does is more akin to a gamma change within each ISO.


I am glad you are lecturing the guy who makes the color science for BMD.
Color science me impressed.
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John Griffin

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostWed Jun 07, 2023 3:20 pm

So what's your understanding of what 'ISO' means?
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Sean van Berlo

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostWed Jun 07, 2023 3:22 pm

Having the ISO behave this way is incredibly more useful for both monitoring and post than arbitrarily following an antiquated idea of how it 'should' behave because of convention, in my opinion.
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Michel Rabe

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostWed Jun 07, 2023 3:53 pm

John Griffin wrote:So what's your understanding of what 'ISO' means?


Does it matter?

Sean van Berlo wrote:Having the ISO behave this way is incredibly more useful for both monitoring and post than arbitrarily following an antiquated idea of how it 'should' behave because of convention, in my opinion.


+1
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John Griffin

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostWed Jun 07, 2023 3:59 pm

Sean van Berlo wrote:Having the ISO behave this way is incredibly more useful for both monitoring and post than arbitrarily following an antiquated idea of how it 'should' behave because of convention, in my opinion.

I agree that having the ability to change the tonal distribution within a gain stage is incredibly useful but why confuse everyone by calling it 'ISO' ?
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John Brawley

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostWed Jun 07, 2023 4:07 pm

This is how most cameras work. The underlying native EI is the same. The ISO here is a curve that’s applied.

I think maybe Canon are the only ones that do seperate analog gain in-camera / on-sensor. I think? I might be wrong on that too.

ISO has always been a problematic term for digital cameras. EI is probably what should be used but everyone still calls it ISO.

I don’t know why RAW is always capitalised but no one writes raw either.

JB
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John Griffin

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostWed Jun 07, 2023 6:05 pm

John Brawley wrote:This is how most cameras work. The underlying native EI is the same. The ISO here is a curve that’s applied.
JB

In my experience of other cameras the curve stays the same shape so the relationship between tones stays the same even if you loose DR and gain noise (a user choice).It only happens on other cameras when you switch between profiles and hence why 'LOG' profiles have raised base ISO's as the underlying EI is the same but the midtones are raised which is where the ISO is traditionally calculated from as a film legacy metric. I think either approach is valid and has it's pro's and cons but they both can't be called 'ISO' without introducing a lot of confusion in endless threads like these.
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CaptainHook

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostWed Jun 07, 2023 7:28 pm

John Griffin wrote:A true ISO change shifts all the data up or down by the same amount just as a change of aperture or shutter angle does

That IS what is happening with Gen 5. But the exposure tools on camera are adjusting to show you something useful.

Again, do the test in Resolve. Changing the ISO will show the data is linearly scaled across the range. The curve does not change.
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John Griffin

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostThu Jun 08, 2023 9:23 am

I was just identifying the in-camera ISO control and not the Resolve exposure tools.
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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostThu Jun 08, 2023 9:35 am

John, you're not reading Hooks posts carefully. He's talking about the in-camera iso control. Also maybe consider that the guy who wrote the book on gen5 and braw has to know what he's talking about.
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John Griffin

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostThu Jun 08, 2023 10:26 am

I am reading Hook's posts very carefully. Will post some tests next week when I'm back in the studio.
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Howard Roll

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostThu Jun 08, 2023 3:24 pm

Does 400ISO film have the same noise or tone curve as 3200? Even within the same ISOs chemical film is going to have different tonality depending on the brand or type.

Does any digital format have the same distribution of stops given the same parameters?

An unrealistic expectation is being asked.

No format, chemical or digital, is the same, why should BM be held to a standard that doesn’t exist for any other media?

As many have said before, your camera is your film stock. Rate the sensor and push/pull accordingly.

Good Luck
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John Griffin

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Re: 6K Pro 2nd Native ISO at 1250 not 3200?

PostThu Jun 08, 2023 3:46 pm

Howard Roll wrote:Does 400ISO film have the same noise or tone curve as 3200? Even within the same ISOs chemical film is going to have different tonality depending on the brand or type.

Does any digital format have the same distribution of stops given the same parameters?

An unrealistic expectation is being asked.

No format, chemical or digital, is the same, why should BM be held to a standard that doesn’t exist for any other media?

As many have said before, your camera is your film stock. Rate the sensor and push/pull accordingly.

Good Luck

Most film will conform to a very similar tonal response. Back in the day when I shot colour film it would be very difficult to print it if the response curves differed greatly between brands. B&W was more flexible as you have different contrast papers but the tonal response was generally very linear in the midtones. Every manufacturer has their own take on 'LOG' but this is not the same as them having their own take on what ISO control does. Again I think BM's approach is valid but it's not strictly ISO and it's different to other manufacturers and causes confusion. I will post some evidence soon.
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