Exposing + Native ISO

[Will Keir]

Mark's post is pretty dead on.

Really Phil? Which one?

His first post, #2 where he states ISO changes exposure?

You should lower the ISO to allow more light into the sensor. More light = cleaner image.

Quite the opposite in Post #22.

and while the ISO does not effect the actual exposure

I'd like to add to this conversation just a bit.

Usable Range.
As several people have pointed out Dragon is happy to shoot ISO 250-2000. This is what Red publishes as "fit for theatres or publication". I agree with that and this range is the basis of success when attempting to shoot "clean". You can indeed explore outside of that range however.

I would just add a guide:

250 ISO for extreme noise protection. Your cleanest image in a dark room.
2000 ISO for your extreme highlight protection shooting into the sun.

and

Good Luck shooters. See you in those dark rooms and blow out sunny days!

 

[Phil Holland]

Its a dead horse but I have to say this thread again shows that Red's concept of ISO, RAW and metadata confuses people and leads to misconceptions. Gladly Red's sensors have enough DR to cope with unnecessary high ISOs leading to underexposure. 5 years ago this has been the conservation: what do you think is 5298 like, full 500 ASA on night exterior shots? Not really. Open up half a stop is a good idea. I rate it 320 ASA, maybe 500 for flat conditions such as shooting in a Portuguese restaurant with all those fluorescent lights.

Why can't we have that with digital cameras? Red could write 640 ASA on the Dragon sensor and off we go. Mentioning ISO 3200 as a viable way leads to very noisy pictures in night exteriors and dark interior shots. Alone the number 3200 raises expectations that won't hold up in the real world and lead to disappointment. There are plenty of posts here in the boards that clearly show that.

How many shots are postet with Neat Video treatment? Seems that to many Red and Neat Video are a natural tandem. Oh well.

I thought I was fairly clear in my reply. And I think what you're describing is what many have misconceptions over exactly how ISO works in all cameras.

ISO 250-2000 for clean "theater ready images". Explore other higher ISOs if looking for a unique textured look.

This doesn't need to be a difficult thing to understand or explain to others.


Here's the 4 most important concepts.

- ISO does not effect the light coming into the camera.
- ISO does effect where you "rate" your midtones.
- Expose within the recommended usable range for best results, ISO 250-2000.
- If exposure values land in the Noise Floor using higher ISO values (2500+) can produce visible image noise.


Or in a graphical explanation:

Red Dragon: ISO and FLUT Breakdown



The above graphic shows how ISO and FLUT work with the Red Dragon Sensor. The total Dynamic Range is always captured, however, when rating middle gray at a higher or lower ISO values the tonality is compressed or expanded across the captured dynamic range. The main advantage of this method being always having access to the maximum Dynamic Range and not inducing Clipping or Crushing when adjust ISO or FLUT in post.

It's interesting that you mention this:

"Red could write 640 ASA on the Dragon sensor and off we go"

As that's sort of what you can do and they do actually do. This is why most productions shoot at a chosen ISO and stick with it for the entire shoot.

I sometimes think of ISO more or less as a "film stock's look" both in texture and tonal placement.

 

[Will Keir]

EXPOSURE CHECK.
VIDEO CHECK.

Phil. Would you mind explaining these two tools as you did so well with stops lights and goal posts? How to use them exactly, perhaps with some images? Is there still a need for a light meter? I'd love to get the correct information up on a sticky. Simple, only the words and explanations that matter, as a reference to send people who are interested in learning proper exposure.

It took me a couple years to learn this stuff and I still don't use all the tools in camera.

If you want to create a sticky Phil, I'd be glad to proof read and edit for simplicity. You pretty much have all the basic's covered in your post #33. Valuable stuff Phil, much appreciated and keep up the good work, reinforcing value and spreading clarity for us all.

However, the camera has on board tools that everybody should get very familiar with. It's very easy to use the tools on camera (Exposure Check and Video Check) to quickly make sure you are getting exactly what you want.

 

[Phil Holland]

Really Phil? Which one?

I was referencing the last quoted post, but hopefully that didn't lead to confusion. Hopefully my explanation was clear enough to get the thoughts across.

EXPOSURE CHECK.
VIDEO CHECK.

Phil. Would you mind explaining these two tools as you did so well with stops lights and goal posts? How to use them exactly, perhaps with some images? I'd love to get the correct information up on a sticky. Simple, only the words and explanations that matter, as a reference to send people who are interested in learning proper exposure.

It took me a couple years to learn this stuff and I still don't use all the tools in camera.

If you want to create a sticky Phil, I'd be glad to proof read and edit for simplicity. You pretty much have all the basic's covered in your post #33. Valuable stuff Phil, much appreciated and keep up the good work, reinforcing value and spreading clarity for us all.

Heh. I might make a graphic and attach it to my Dragon Data Sheet thread. Much of this is covered in the Epic Operation Guide under "Appendix I: Exposure - Using False Color and ISO" and also the section on Video Check explains where various values come into play.

I'll see what I can put together. The manual is verbose for a reason, but much of this can be shown in a couple graphics with simple text.

 

[Will Keir]

Phil,

Would consider making a little short BTS appendices for the manual?

I'll see what I can put together. The manual is verbose for a reason, but much of this can be shown in a couple graphics with simple text.

 

[Hans von Sonntag]

Here's the 4 most important concepts.

- ISO does not effect the light coming into the camera.
- ISO does effect where you "rate" your midtones.
- Expose within the recommended usable range for best results, ISO 250-2000.
- If exposure values land in the Noise Floor using higher ISO values (2500+) can produce visible image noise.

Phil, frankly, you, I, and other seasoned reduser understand the above mentioned points. The majority don't. They dial in ISO 2000, the monitor gets visibly brighter and go happily shooting night exteriors and come back with a bunch of noisy shots. One could tell them, oh you are freshmen, don't you know that high ISO is to a certain extend good for sunny high-contrast environments and low ISOs are your best friend für night exteriors?

If they knew that the Dragon is a ISO 640 Sensor (just to grab a number) and altering the ISO is not a good idea if noise could be an issue then we had much, much less complaints about Red building noisy cameras. Arri somehow managed that and made clear that Alexa is a ISO 800 device, full stop. Telling from these boards I have the feeling that this is not the case with Red. Seen Dragon as a ISO 2000 Camera is the more spectacular story.

Porsche, for instance, publishes traditionally lower numbers in their specs as actual tests later reveal. I like this approach much more, it creates less disappointment and makes everybody more happy.

It's interesting that you mention this:

"Red could write 640 ASA on the Dragon sensor and off we go"

As that's sort of what you can do and they do actually do. This is why most productions shoot at a chosen ISO and stick with it for the entire shoot.

I sometimes think of ISO more or less as a "film stock's look" both in texture and tonal placement.

This is what I do. Epic is an ISO 320 camera, with a potential to underexpose 1 stop without exhibiting distracting noise depending on the environment. But red marketed Epic as an ISO 800 camera, which ist the meaningful edge for noise free pictures, and in the case of low light scenes it is over the edge. I chose ISO 400 for all I do with the Epic. Same as I rated 5298 as 320 ASA like 95% of the colleagues did. With film we never had those issues. But then we could not make the VF brighter and underexposing effectively the shots and telling people later: it's alle metadata, it's all in there, it's all RAW, you know... Ok. Let's check Neat Video.

I'm exaggerating of course but you get my point. Being more humble with declared ISOs would be better for Red's reputation. Noise is noise, all this talk it depends on how much you can bare, taste.... etc... is in the end meaning, feeling, faith, but not facts. Red's customer is not the low-light, available-light shooting shallow focus loving DSRL crowd.

Hans

 

[Gunleik Groven]

Will.

I will not further confuse the matters with my explanations.

Phil is an excellent explainer.

I will leave this thread, with a last remark, though...

There is one thing ISO does not, which is: Change exposure (as in changing the amount of photons hitting the sensor)

But we use ISO to change exposure: As in rating what amount of light we will let the camera be exposed for.

ISO does not do that, the operator does.

Hans and Phil (and Mark) are spot on, in the posts I have seen.


But there are enough cooks and different language that may not communicate as well to all users in this thread for my to add any further.

 

[David Battistella]

You know what we need.

DPs on sets. Like, I want to hear (and probably a lot more people want to hear) Peter Lyons Collester explining how he got those stunning images fo spiderman. We want to see how guys ae rating and lighting and using the tool.

Middle grey charts are nice, but I think people want to see the camera in action on real sets and see how different people are rating RED. RED could follow Mark Toia on his next shoot (id be willing to shoot and edit it) and talk to him while is in between shots abot what he is doing with a particular scene. A green screen set on one of those mega films. Bjorn Beckart on an international commercial taking yuo from the set through a post process. Some big video set wih Dino G . A photography shoot in London or Paris or Milan.

This kind of campaign would be an absolute FUD killer. Id shoot it all run and gun and explin that process too.

I have had and seen the best results when people treat RED as a FILM STOCK and light accordingly.

If Dragon actually can be rated 250-2500ISO with no penalty then we have the digital equivellent of every film stock ever made and that would be a minor miracle.

Battistella

 

[Stephen Williams]

You know what we need.

DPs on sets. Like, I want to hear (and probably a lot more peoplewantto hear) Peter Lynos Collester explining how he got those stunning images fo spiderman. We want to see how guys ae rating and lighting and using the tool.

Middle grey charts are nice, but I think people want to see the camera in action on real sets and see how different people are rating RED. RED could follow Mark Toia on his next shoot (id be willing to shoot and edit it) and talk to him while is in between shots abot what he is doing with a particular scene. A green screen set on one of those mega films. BjornBeckart on an international commercial taking yuo from the set through a post process. Some big video set wih Dino G . A photography shoot in London or Paris or Milan.

This kind of campaign would be an absolute FUD killer. Id shoot it all run and gun and explin that process too.

I have had and seen the best results when people treat I as a FILM STOCK and light accordingly.

If Dragon actually can be rated 250-2500ISO with no penalty then we have the digital equivellent of every film stock ever made and that would be a minor miracle.

Battistella

I did some green screen tests with Dragon last week, 400 ISO with 7:1 compression was ideal. Quite similar performance noise wise as another high end camera. I would not have wanted to use more than 5:1 with MX

 

[Hans von Sonntag]

I did some green screen tests with Dragon last week, 400 ISO with 7:1 compression was ideal. Quite similar performance noise wise as another high end camera. I would not have wanted to use more than 5:1 with MX

Thanks Stephen. Your findings regarding ISO matches mine pretty well. For cleanest results exposing near to the "native" sensitivity is meaningful.

----

I use LUTs and grain intensively in my Smoke systems. Grain can be added later in subtle dose-rates. No reason to introduce grain in the footage unnecessarily. I'm sure Dragon will end up in my hands as an ISO 800 camera for most things like the MX has been a ISO 400 camera. However, for GS opening aperture just about a stop makes sense.

Hans

 

[Mark L. Pederson]

Really Phil? Which one?

His first post, #2 where he states ISO changes exposure?



Quite the opposite in Post #22.





I would just add a guide:

250 ISO for extreme noise protection. Your cleanest image in a dark room.
2000 ISO for your extreme highlight protection shooting into the sun.

and

Good Luck shooters. See you in those dark rooms and blow out sunny days!

Will - you are taking me out of context - when I said "You should lower the ISO to allow more light into the sensor. More light = cleaner image." I was SPECIFICALLY responding to a question a user posted where he asked if he should leave ISO at 2000 and then limit the light with NDs vs lowering the ISO. You should re-read that post. I guess I should have said "You should lower the ISO vs. keeping at 2000 and adding ND filters as to allow more light into the sensor. More light = cleaner image." - but the guys question was quoted in my response.

 

[David Battistella]

I did some green screen tests with Dragon last week, 400 ISO with 7:1 compression was ideal. Quite similar performance noise wise as another high end camera. I would not have wanted to use more than 5:1 with MX

Let's do it.

Keep me posted on your next shoot.

Battistella

 

[Mark L. Pederson]

This is a simple solution really. EDUCATE people on what is actually happening like Gunleik, David and Bjorn have pointed out. A solid understanding is the basis of a solid foundation when using the Epic. Once they understand the concept you free them to use ISO as a tool for both highlight protection and to avoid unwanted noise. They will understand exactly what is going on with their tools, empowering shooters/filmmakers to make the best choices for their vision.

Understand why it is happening, fix the problem(s), simple stuff.

"9 out of 10 times..." all the more reason to break down the basics and work up from there. If it can't be explained simply, it's a problem with the teaching, not the students.

#1. ISO does not effect exposure, the amount of light hitting the sensor. Adjusting ISO will not change your amount of highlight protection or protect you from added noise. The only way to change exposure is to add/subtract light, adjust aperture, shutter speed or use of NDs. Changing exposure in these ways can save you from unwanted noise or give you protection in your highlights.

If you keep teaching down to DP/Filmmakers, you will continue the fog of misinformation. Which started with post #2, even though it's obvious Mark has a great understanding of the Epic platform.



Agreed, RED needs to fix this misleading tool.

Will - it's actually not a hard concept to understand. We've been doing it for decades.

35mm motion picture film - it has an ISO rating on the can. Let's say it's 500. That's a recommended ISO. That number does NOT effect how much light goes into the motion picture film camera. Only aperture, filters and shutter do (sound familiar). It's a recommendation for how a DP and/or Gaffer should set his/her light meter as to measure light to set an exposure - aka exposure method.

Now, some DPs would rate that same film stock at 640 - some at 320 - and by changing the rating - changing the ISO - no more or less light came into the camera - it's just a setting on the light meter ...

BUT .....

By changing the rating on the light meter .... his/her CHOICE (method) of exposure is changed as the light is now metered differently.

We now have the other elephant in the room with respect to monitor path - as we only had a flickering black and white shit video tap attached to an viewfinder for the longest time in film. So nobody ever argued with the exposure setting.

Now ... you have to ask yourself ... all those movies ... THOUSANDS of movies shot in film ... no histogram. No stoplights. No monitor path. No false color. How did they manage to get the right exposure?

It was their job to understand ISO and rating the light meter - and how THEIR EXPOSURE METHOD (using a light meter) created results on a GIVEN FILM STOCK.

MX is a film stock.

DRAGON is a film stock.

The last Reducation class I taught I asked the class to raise their hands if they understood what Contrast Ratio meant. One person raised their hand and had the wrong answer. I believe that the DSL and digital camera movement has pushed the "point and shoot" and "WYSIWYG" thing so much ... the newer generations are sadly missing the most fundamental basics of cinematography/photography.

And that is most likely why still photographers find RAW easy. Because still photographers typically have a very solid foundation of the fundaments of photography. They are focused on their choice of settings and exposure method instead of a monitor path.

 

[Paul E. McCarthy]

Will - it's actually not a hard concept to understand. We've been doing it for decades.

35mm motion picture film - it has an ISO rating on the can. Let's say it's 500. That's a recommended ISO. That number does NOT effect how much light goes into the motion picture film camera. It's a recommendation for how a DP and/or Gaffer should set his/her light meter as to measure light to set an exposure.

Now, some DPs would rate that same film stock at 640 - some at 320 - and by changing the rating - changing the ISO - no more or less light came into the camera - it's just a setting on the light meter ...

BUT .....

By changing the rating on the light meter .... his/her CHOICE of exposure is changed as the light is now metered differently.

We now have the other elephant in the room with respect to monitor path - as we only had a flickering black and white shit video tap attached to an viewfinder for the longest time in film. So nobody ever argued with the exposure setting.

Now ... you have to ask yourself ... all those movies ... THOUSANDS of movies shot in film ... no histogram. No stoplights. No monitor path. No false color. How did they manage to get the right exposure?

It was their job to understand ISO and rating the light meter - and how THEIR EXPOSURE METHOD (using a light meter) created results on a GIVEN FILM STOCK.

MX is a film stock.

DRAGON is a film stock.

The last Reducation class I tought and asked the class to raise their hands if they understood what Contrast Ratio meant. One person raised their hand and had the wrong answer. I believe that the DSL and digital camera movement has pushed the "point and shoot" and "WYSIWYG" thing so much ... the newer generations are sadly missing the most fundamental basics of cinematography.

Mark is Correct.

And the application of this is called shooting the "Toe" or shooting the "Shoulder",

Its a common practice for film guys through history until the Vision Stocks came out. Most DPs shot only 200TASA (5293) stock and never set there light meters to 200ASA ever.
They would shoot day and night because the early 500ASA was so grainey or as we say now noisey (sad that grain is called noise, so negative)and shooting different stocks was always jarring in the edit.

If you are going for a darker look, night interior, you shot test for the toe, the bottom of the stocks DR and sensitivity. You are going for blacks, skin exposure and protecting grain,not concerned with highlights, it not interior and you can put practicals on dimmers.

You might find that rating the film at 500 gave you much better results because you found some extra DR in this chemical batch of film which ranged quite a bit in the 90s. From 200ASA to 500ASA is a doubling of light. That is a huge amount a light at 200ASA you don't need now.

And vice versa with shooting "shoulder."

If you are going for skies or highlights or windows, you shoot and test for the Shoulder. And rate the same stock accordingly maybe at 100ASA to get that cloud detail.

Just because DR is there, doesn't mean that that info has to go on the screen, you get to choose, that's your call.



find your Toe or Shoulder sweet spot.

I decide to shoot the shoulder or toe and ETTR.
I never had a problem getting a black in post so I tend to open up for Night interiors and stop down for day exteriors

If 800 is clipping, always ND if you can to the native rating of the camera that's always the best, if youre out of ND and you need to roll the ASA down to hold the skies just do it. Your contrast will go up, so pull some out in your look settings,

 

[Scott Crawley]

I'm with Mark on this just as I believe in his suggestions about RAW view. (See thread: Truth or False Color.)

It may be time to assign the chips a sensitivity and color temp rating just like was done with film stock. It would probably be more helpful in the long run if the ISO scale were not used in rating them for a number of reasons, but that might be too much too fast.

People need to stop thinking of the chip as having adjustable sensitivity. It does not, but including an ISO adjustment apparently misleads many to believe exactly that. It may be time for the elimination of the ISO control slider. In it's place, expand the FLUT slider to incorporate the full range of the current ISO adjustment and give it a coarse and fine control.

 

[Mark L. Pederson]

People need to stop thinking of the chip as having adjustable sensitivity. It does not, but calling that adjustment ISO apparently misleads many to believe exactly that. It may be time for the elimination of the ISO control slider. In it's place, expand the FLUT slider to incorporate the full range of the current ISO adjustment and give it a coarse and fine control.

No. That's crazy IMO.

EVERY digital camera let's you adjust ISO - and it's a powerful tool to manage your DR. And while SOME people struggle to understand it - MANY of us - understand it and leverage it.

I think this whole issue is about EDUCATION.

It's not a RED thing - you can adjust ISO on the Alexa, F65, F55, etc. etc. - it's a result of RED facilitating more people having access to a powerful tool and having an open, public forum.

Again, back in 35mm days - you had to know your shit before someone let you choose a F stop on the lens and let hundreds and hundreds of dollars worth of celluloid rip through a magazine.

Today ... these tools are so powerful that you can get a "reasonable" image without knowing anything -

BUT - if you want to leverage the tool and make GREAT images ... You need to know your shit. You need to know the fundamentals. If it is confusing to you - keep asking - read books - seek out a mentor - get a shitty job under an expert and then pay attention to every single thing he or she does.

Go to Reducation

When I first got my hands on Dragon - I thought - WOW - this is REALLY like film. Screw the histogram - get a light meter if you want to get everything out of this camera!!!

Making the camera "dumber" - or eliminating powerful tools that some people have trouble understanding is NOT the answer.

Ask me anything. I'm here - I'll do whatever I can to help.

 

[Scott Crawley]

You have clearly thought this out much more than I, and have a deeper understanding so please bear with me. Thank you for entertaining my questions and helping me to navigate this.

The ISO control is a misnomer. I simply suggested that it be given a more appropriate name, not to eliminate the tool or limit the control. What could be wrong with eliminating that source of confusion? The ISO control and the FLUT control are the exact same adjustment, are they not? My understanding is that they are neither ISO nor gain control. Is that correct?

It may seem like a dumbing down but it really isn't. Educated digital shooters will understand how to push the chips just as they knew how to push a film stock, and less re-education will have to be done if the terminology is not misused or re-purposed.

 

[Mark L. Pederson]

The ISO control is a misnomer. I simply suggested that it be given a more appropriate name, not to eliminate the tool or limit the control. What could be wrong with eliminating that source of confusion? The ISO control and the FLUT control are the exact same adjustment, are they not? My understanding is that they are neither ISO nor gain control. Is that correct?

Nope. It's NOT a misnomer. It's exactly what it should be called - it's how almost every digital camera works - and it's how photographers and cinematographers have worked for decades on film and now on digital.

From Wikipedia ISO -

"In digital camera systems, an arbitrary relationship between exposure and sensor data values can be achieved by setting the signal gain of the sensor. The relationship between the sensor data values and the lightness of the finished image is also arbitrary, depending on the parameters chosen for the interpretation of the sensor data into an image color space such as sRGB.
For digital photo cameras ("digital still cameras"), an exposure index (EI) rating—commonly called ISO setting—is specified by the manufacturer such that the sRGB image files produced by the camera will have a lightness similar to what would be obtained with film of the same EI rating at the same exposure. "

I'm going to go out on a limb here -

I think that any person who is confused by what ISO does or doesn't do on a RED camera - does not know how to use a light meter to measure light - and thereby - would have no idea how to set exposure for a film camera with a given filmstock (with a recommended ASA/ISO rating).

Because ... IF they knew how to do that ... they would understand exactly what is going on with a RED camera with ISO. (or an Alexa, F65, F55, etc etc,)

Would you not agree?

Is there ANYONE out there that is confused by ISO that knows how to choose an exposure correctly if I handed them a 35mm camera loaded with Vision 3 and a light meter?

So again ... I think this is about EDUCATION - and I think what is SADLY MISSING these days is the very fundamentals of photography/cinematography.

 

[Scott Crawley]

Nope. It's NOT a misnomer. It's exactly what it should be called - it's how almost every digital camera works - and it's how photographers and cinematographers have worked for decades on film and now on digital.

From Wikipedia ISO -

"In digital camera systems, an arbitrary relationship between exposure and sensor data values can be achieved by setting the signal gain of the sensor.

I don't know if we need a Red Engineer to clear this up but I believe this is incorrect.

Also according to WIKI:
"In electronics, gain is a measure of the ability of a circuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output, by adding energy to the signal converted from some power supply."

Does the ISO setting on Red actually boost the electrical signal coming from the sensor or does it simply redefine the relationship of the response curve to the scale?

 

[Terry VerHaar]

Does the ISO setting on Red actually boost the electrical signal coming from the sensor...

NO

or does it simply redefine the relationship of the response curve to the scale?

YES

:smiley: