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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Native Dragon ISO…once and for all!

One thing I know many folks don't experiment too much with are the various scaling methods that can be configured through Redcine-X Pro's export settings. That's a lot of fun. I've been tinkering a lot on finishing Dragon material at various capture resolutions and the finish resolutions of DCI and UHD 4K.

The conversation about texture/noise/grain is fascinating as one of the first tests I had to fire off with Dragon literally the first month I had the camera was a texture comparison compared against film. Which I had to do again when the Skin Tone - Highlight OLPF was released as well. The general concern and consideration for certain interested studios was to discover is the texture across Dragon's ISO ratings was considered "pleasing" and not too "energetic", digital, or chromatic to distract viewers. After all that was done it was pretty easy to discover that Dragon is cleaner that film at various ISO/ASA rating comparisons. Oddly, I think whatever Red is doing under the hood in regards to Dragon's actual texture is pretty cool. That is if you are looking for your motion pictures to contain that sort of characteristic.

Clients, producers, and filmmakers have desires across the board when it comes to texture. When clean is wanted it becomes needed. That often for me is happening in the commercial world. Narrative seems to be where texture can live to see the light of day. There's just not one answer here that's truly "right". Some want to add grain in post, some want to remove noise in post, some don't want to deal with any of that.

Back to the topic at hand. Dragon's recommended usable range is ISO 250-2000. That is 4 stops. For me much of what I really like happens in ISO 500-1000 for narrative.

Just to say a few things about the OLPFs that I've covered elsewhere:

The more recent development of the Interchangeable OLPFs has been interesting. The Low Light Optimized OLPF when comparing texture against the Skin Tone - Highlight OLPF appears to be about 1 to 1.3 stops cleaner. Because of the way ISO works with Dragon you can make the argument that it sees that much more into the shadows as you can certainly get very usable ISO 2000 and I've shown pretty decent ISO 4000/5000 examples here. The Skin Tone - Highlight OLPF tends to have a slightly nicer hold on the highlights prior to clipping. For me the STH OLPF is about as "film-like" as it gets in terms of the more analog look to the footage.
 
Since the beginning of times cinematographers used film with different ISO. So, when they wanted clean images, they used film with ISO 50. When they needed more sensitivity and grain, they used film with ISO 800. They also could push and pull film development, if needed. And then there were other film emulsions as well, if needed. Funny thing, no one was confused about which ISO to use and no one had asked why isn't there a single ISO film stock:)
On the other hand I can see why people still not clear on the concept of using higher ISO, when shooting bright scenes, like outdoors. It can be counterintuitive and confusing, but it does make sense upon closer inspection.
So, from my point of view, as a colorist- right now there are two "native" Dragon sensitivities, akin to two available "film stocks"- 250 for Skin Tone and 800 for Lowlight. Use 250 for very clean images and 800 and up for more "texture".
Pretty simple…
 
Jake... you mean 800 for Low light OLPF and not High light OLPF, yes?
 
Brian Boyer said:
Lower ISOs distribute more stops below middle gray and higher ISOs place more above middle gray. Darker scenes rated at low ISOs, when exposed correctly, benefit from both more light on the sensor (from adding more lights, opening the lens, increasing shutter angle) and the greater concentration of stops dedicated to shadow detail.

Bright scenes, which usually have less intense shadow areas, benefit more from the greater overexposure latitude of higher ISOs. This way, you're not wasting stops in the shadows, where you don't need them as much, and putting them where they'll do the most good, at the top.
Click to expand...

This definitely clears it up a bit.
 
jake blackstone said:
Since the beginning of times cinematographers used film with different ISO. So, when they wanted clean images, they used film with ISO 50. When they needed more sensitivity and grain, they used film with ISO 800. They also could push and pull film development, if needed. And then there were other film emulsions as well, if needed. Funny thing, no one was confused about which ISO to use and no one had asked why isn't there a single ISO film stock:)
On the other hand I can see why people still not clear on the concept of using higher ISO, when shooting bright scenes, like outdoors. It can be counterintuitive and confusing, but it does make sense upon closer inspection.
So, from my point of view, as a colorist- right now there are two "native" Dragon sensitivities, akin to two available "film stocks"- 250 for Skin Tone and 800 for Highlight. Use 250 for very clean images and 800 and up for more "texture".
Pretty simple…
Click to expand...

Yep. I'm more or less on that boat, though I'm a little more "variable" in my ISO ratings and uses.

Pretty much after the first round of testing with Dragon I found I can work more or less identically to how you would work with film.

How it happens in my mind: choose my Stock/ASA (meaning choosing my ISO Rating on Dragon) and proceed to shoot. Did and done.

I choose my rating per project and at a sub-level per scene if needed. Just like I would if I was shooting the project on celluloid.


My general way of working:
Skin Tone - Highlight OLPF: ISO 250 for the cleanest image, ISO 500 for me is a nice middle ground, ISO 800-1280 for the most "film-like" image.
Low Light Optimized OLPF: Where cleaner images are desired and certainly for ISO 2000 or even a bit beyond. Useful for high frame rate/over cranked work as well when cleanliness is important.
 
Let's get the terminology straight.

LLO = Low Light Optimized

STH = Skin Tone Highlight

H20 = Underwater specialist.


battistella
 
This is one of the better threads I have read in awhile and a very healthy conversation. Thanks for the OP, Jarek.
 
Brian Boyer said:
I'll take a stab at this. To the best of my knowledge...

Lower ISOs distribute more stops below middle gray and higher ISOs place more above middle gray. Darker scenes rated at low ISOs, when exposed correctly, benefit from both more light on the sensor (from adding more lights, opening the lens, increasing shutter angle) and the greater concentration of stops dedicated to shadow detail.

Bright scenes, which usually have less intense shadow areas, benefit more from the greater overexposure latitude of higher ISOs. This way, you're not wasting stops in the shadows, where you don't need them as much, and putting them where they'll do the most good, at the top.
Click to expand...

Really well put. Thanks Brian!
 
I have not posted in a while (been super busy with several projects), but I want to share my PoV...

IMHO Daniel is the one that really "gets" the ISO. When it comes to RED - you need to "forget" everything you know about ISO/ASA and their traditional uses, whether that be still or motion photography.
The brutal and plain fact is that on RED the ISO has no influence on the RAW data what so ever.
When it comes to using RAW camera like RED - any images that we see - whether on the LCD, clients monitor, or in post - are just an "interpretation" of the RAW data. The data itself does not change. What the ISO has an influence on is this interpretation - and as a consequence that influences us on how we light and expose our imagery.
I have long had the luxury of mostly working on projects where I decide how to expose, monitor and process the RAW data.
I always use RAW monitoring (that ignores the ISO completely) and make sure to light and expose my imagery with the single purpose of capturing the best RAW data I can. This mostly results in a imagery that is not very "pleasing" to people who do not understand the power of RAW - which unfortunately includes most clients. But through consistent great results in final imagery - I have convinced my clients to trust me...

And here lies the main issue with ISO (in my honest opinion) - the monitoring, or more correctly the " interpretation" of RAW data during principal photography. Traditionally the director and/or clients are used to see a monitoring image that closely resembles the look you are after. Putting aside the craft of lighting and composing your scenes - this meant what film stock you chose, which lenses and your filtration - all of which would define your imagery. Working with RAW camera you can use the ISO (and the various color spaces, curves and other image adjustments) to "preview" what the footage could look like - or once again - one of the possible "interpretations". But you need to understand what that truly means and not let this preview to influence you in making changes to the scene, exposure, or filtration - which WILL affect your RAW data. This is a concept that is rather alien to most DP's and takes some time getting used to...

Building on what Daniel said earlier - once you ignore the actual scene and its lighting configuration - there are only four things that influence the light reaching the sensor - and therefore the RAW imagery (in order from scene to sensor):

- the filtration
- the lens (including its iris)
- the OLPF (which is now interchangeable on Dragon)
- the shutter (whether mechanical before OLPF, or electronic on the sensor itself)

Change any of the above and you WILL change the RAW data. Change any settings on the camera - and particularly for this thread the ISO - and the RAW data DOES NOT change. What changes is the interpretation of the RAW data that you see on the monitor...

So the real question is not what is the native ISO - if by ISO we mean the actual ISO setting on the camera - but what is the actual native sensitivity of the sensor itself while purely examining the RAW data. And here is the real problem - you can't really see the RAW data without it being interpreted in some way. In order to get useable (visible) imagery from the RAW data - it needs to be processed (interpreted) - which is where ISO setting does play a role. If we were to see the true RAW data of the sensor - it will make no sense to us at all, as we would be looking at the native RGBG Bayer matrix. The RAW view option on the RED is as close as we can get - and this is why it is my preferred mode of monitoring. But the RAW image is mostly unacceptable for the director and/or clients. My solution is to work with my director/clients to establish the target look during initial tests and then have this preset for live playback on the set. I have "trained" them to ignore the look while recording and only focus on the action and composition. Then they get to see the look (interpretation) while we play back after the take. After a while they get completely used to it. It's not ideal, but it works for me...

What I would love to see from RED is the ability to monitor RAW on one output (be it the on-camera LCD or EVF), while outputting the "interpreted" imagery (including the ISO choice amongst other settings, such as color science, space, etc...) on all the other outputs during recording. Even if that meant a new module...

So in conclusion - there is no native ISO in the sense that we normally understand it.
The closest you could get is to compare the RAW view against another non-raw camera where the ISO does influence the exposure in the same way a light meter would recognize. But then you would need the same sensor and make sure that nothing else is going on - which is impossible. And if you wanted to reference film ISO - the question becomes which film stock? And in any case - we can't see film exposure live while capturing...

So in the end you need to do your homework. Learn how the sensor responds under RAW view and how that is influenced by ISO interpretation (and other settings). Do not use the image interpretation (influenced by the ISO) to guide how you expose your scene (by changing any of the four elements listed above) - UNLESS you fully understand that interpretation and what it does to your imagery.

:sifone: Peter
 
Bob, I am indeed looking forward to this function, however it seems (and I would love to be proven wrong!) that you can only change the LUTs. LUTs are applied at the end after color science, color space (and ISO) are chosen first. Therefore I do not think this function would allow us to actually separate color space / science combo between various monitoring paths - which would allow to get RAW on one of these paths. Again - it would be wonderful if I am wrong and this will indeed solve this issue... ;o)

:sifone: Peter
 
Peter Majtan said:
So in the end you need to do your homework. Learn how the sensor responds under RAW view and how that is influenced by ISO interpretation (and other settings). Do not use the image interpretation (influenced by the ISO) to guide how you expose your scene (by changing any of the four elements listed above) - UNLESS you fully understand that interpretation and what it does to your imagery.

Peter
Click to expand...

This has been preached around here endlessly as well as the fact that ISO has no effect on exposure (unless you use it as part of your rating and exposure toolkit).

What I mean by that is this. If you, as the cinematographer assign an ISO rating to the scene and light and expose according to that rating. This will have a huge effect on the RAW image data (just as it would with film.

So. If I rate an exterior scene at 2000ISO and use ND, shutter and IRIS to "expose" that way, the RAW data will be underexposed but it could be a creative choice. If I rate the same scene at 250ISO chances are I will have a MUCH MEATIER RAW negative.

And this is where MANY fups occuer IMHO and from what I have seen here.

a DP gets into a LOWlight situation and immediately thinks it's just OK to start at 2000ISO on the camera. They might thing that on a 2.8 lens they are getting plently of light to the sensor, bbut they are not. The "neg" is often underexposed. Now, let's say you want to push a stop, they have exposed one or two stops under and then want to push another stop. Here you are looking at three stops of exposure difference. We see it a lot here and it is a common problem.

You're advice (and others) is correct, when you get into low light situation the best thing to do would be to take your ISO down to 500 or 400 or 320 (for montioring). This is like the opposite of using higher ISO as highlight protection in daylight.

You are correct in that RAW sensor data is the ONLY and MOST important thing to observe, using the histogram, and RAW exposure tool to see where the highlights blow out and where there is no shadow detail and to understand how much light you have be looking at GOALPOSTS and NOISE bar.

THe only tools that really tell the RAW story are.

1. RAW VIEW
2. HISTOGRAM (Left, center or right?)
3. RAW exposure tool (RED are blown pixels, purple is deep shadow)
4. LEFT GOAL POST (percentage of pixels with noise in the frame)

Course, your light and spot meter come in handy for looking at ratios, but the new zone tool does that as well from a sensor level. :)

Battistella
 
David Battistella said:
THe only tools that really tell the RAW story are.

1. RAW VIEW
Battistella
Click to expand...

I would leave #1 out of this.

RAW VIEW, last time I checked, is simply ISO 800 in RLF with a fixed color temp and all other color parameters nulled.

The only "RAW story" RAW VIEW is gonna tell you is what you image looks like processed at ISO 800, RLF. It IS very helpful IMO if you are doing live grading with Foolcontrol to refer to your image without color parameters/curves applied.

It REALLY should not be called "RAW" - as 90% of the folks out there think it means RAW. It does not. It was actually was called "RAW CHECK" at some point and then shortened to RAW.

It would have been more helpful IMO to have rated RAW VIEW at ISO 400. But it is what it is.
 
Brent@RED said:
This is one of the better threads I have read in awhile and a very healthy conversation. Thanks for the OP, Jarek.
Click to expand...

;) You should be getting my baby back for Dragonization on monday!
 
Mark L. Pederson said:
That's a choice. Works for you and many others. Not a bad choice - BUT - not what I would recommend to someone trying to squeeze all the power out of this sensor.
Click to expand...

I agree it's not for everyone. I prefer highlight retention as a look. Grain never bothered me. With DEB, I think it looks rather nice around 800.

What do you like Mark?
 
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