Opinion POLL: EPIC native ISO = 800 or ISO = 320?

[Terry VerHaar]

If you want something definitive, IMO the best place to start is with the information on the RED web site. You can disagree if you want, but if RED isn't the authority, I don't know who is. Changing the ISO deosn't change the sensitivity of the sensor, it simply changes where middle grey is registered and, thus, introduces highlight protection or noise reduction, depending.

Also, I think is is wrong to talk about changing the ISO as introducing "gain." If I recall the discussion by Graeme and company, RED introduces NO analog gain into the system, ever. Any "gain" in post processing is introduced after the A/D conversion and therefore is not electrical gain in the traditional sense. If someone can point me to something that disputes that, please do. But, that is my understanding.

 

[Will Keir]

This is just a Dangerous post and misleading

SO NOT COOL.

"Dangerous," Humm? It's a common debate, let's get it out in the open and learn what others might have to teach.

"misleading?" Doesn't it say in clear English, Opinion Poll?

"NOT COOL" haha, sorry Lu, didn't mean to offend you. Care to clarify what offended you?


Those "guide lines" you set. Humm...

Tungsten indoors at ISO 500

a touch of noise reduction...

Out doors normal day cloudy skys ISO 640 as long as im not shooting into the sun

Again, a touch of noise reduction. Normal day, 5600k.

Bright day to HOT bright day out doors ISO 800

Native daylight sensor ISO...

1,000 if i want to preserve the white clouds in the bright blue sky.

Highlight protection. Make sense.

So BigLu, for you the Epic has NO NATIVE ISO? Call it BigLu's situational ISO?
I am curious, did you use a light meter when you created "BigLu's situational ISO" guidelines or did they come from gut instinct and years of experience?

 

[Will Keir]

You can disagree if you want, but if RED isn't the authority, I don't know who is.

Both Jim and Graeme have stated it clearly. It's published. Native 800 ISO.

Changing the ISO deosn't change the sensitivity of the sensor, it simply changes where middle grey is registered and, thus, introduces highlight protection or noise reduction, depending.

You said it best. Very simple to understand. "highlight protection or noise reduction."

800 ISO = Highlight protection
320 ISO = noise reduction

 

[Ian Laurie]

Both Jim and Graeme have stated it clearly. It's published. Native 800 ISO.

This is wrong. Native ISO is something that is very much permanent in a digital sensor. Graeme has clearly stated in the past that the Native ISO is in fact 320. However they designed it in such a way as to encourage 800 as the base point. To prove that it is in fact native 320 simply look at the raw. Raw is 320. No debate this is the native sensor iso. Does it work excellent at 800? yes But if you want to know 100% what you are recording. shoot raw, and by forced extension 320.

 

[Adrian Jebef]

It was stated long ago. Native ISO of the MX sensor is 320. Having said that, the camera has been designed to give you the most latitude at 800. They recommend 800, Native is 320.

The camera was "designed to give you the most latitude at 800" because it clips highlights quite harshly. Or in other words: because the EPIC has so much resolution and very little noise floor you're better off underexposing everything by a stop and gaining up your image in Post than exposing at native sensitivity and clipping important highlight detail (otherwise and politically referred to as "protecting the highlights").

 

[Adrian Jebef]

"Native" is a misnomer, it implies there is only one answer. The real answer is whatever works for you, personally I feel I have the most dynamic range, and best tonal rendering with the most pleasing image texture at 800 ISO therefore that is my "Native". If another DP has a different esthetic that more closely fits 320 ISO then that can be his "Native" ISO. There is NO I repeat NO absolute ISO for any imaging device that records RAW. Film had an ISO that was formulated into the emulsion as well as a characteristic curve, these could be manipulated somewhat in processing but it was pretty much set. This just does not apply to linear digital imagers the same way.

I disagree. Every CCD or CMOS sensor has a FINITE and MEASURABLE sensitivity to light. There is only ONE SPECIFIC POINT where the sensor is working at full capacity. We usually refer to this sensitivity as ISO or ASA. True we see logarithmically and a sensor "sees" linearly and both of these must be considered and transformed for proper viewing BUT this doesn't change the facts.

 

[Bob Gundu]

Does it really matter what the native ISO is? What matters is, how to achieve optimal results. I believe this comes with experimenting and experience. It eventually becomes instinctual as to how to expose using the tools within the camera, and what you get back at your desk when color correcting.

 

[Adrian Jebef]

This is just a Dangerous post and misleading

SO NOT COOL.

General guide lines I have my operators set at is

Tungsten indoors at ISO 500
Out doors normal day cloudy skys ISO 640 as long as im not shooting into the sun
Bright day to HOT bright day out doors ISO 800 and even 1,000 if i want to preserve the white clouds in the bright blue sky.

Cheers

Whoa! Don't call the COPS just yet.

"The more ya know the farther y'all go"

:dupe:

 

[Adrian Jebef]

300 fps, without black shading to current frame rate and exposure can result in noise. If a black shade calibration is done when the sensor is cold, you will get noise. Shooting in 2k also increases chances of noise.

Where is this stated in the EPIC user manual?

 

[Carlos Gonzalez]

I have been shooting on the MX sensor since it came out both on RED One and Epic, thousands of hours of footage. I have always rated it at 800ASA with great results, even green screen and tungsten. I started out in the film days when you learned to shoot a "fat negative" in order not to get grain on fast film stocks, the days of 5296. No difference now, if you don't starve your sensor you will be fine.

 

[Matthew Scott]

Shooting at ISO 320 is a really excellent way to trash a stop and a third of your highlight range. There are certainly times I've liked the look of a shot I exposed at 800 set back down to 320 in RCX pro but I've never intentionally set the camera to 320 ISO, it's a waste and if you're friend can't get a good looking image at 800 he either needs to learn proper exposure techniques or send in his camera for repair.

A "good looking image", like you've already pointed out is all subject to taste. You like noise. I don't, and neither do a lot of other people...not from a starting point anyway. I'm just going to play on your words here...

Shooting at 320 ISO is a really excellent way to keep you low-light stuff nice a clean in the blacks. I often intentionally set the camera to 320 ISO if there are a lot of under-exposed areas in my scene (low light). If you're looking for clean blacks then it's a waste of time shooting these kinds of scenes at 800 ISO or above, however, 800 ISO is great for daylight scenes where highlights need protecting. Learning proper exposure techniques is obviously a good idea, but more importantly, testing these ideas yourself, with the MX-Sensor will help you decided which ISO is best, for any given situation.

 

[Adrian Jebef]

I have been shooting on the MX sensor since it came out both on RED One and Epic, thousands of hours of footage. I have always rated it at 800ASA with great results, even green screen and tungsten. I started out in the film days when you learned to shoot a "fat negative" in order not to get grain on fast film stocks, the days of 5296. No difference now, if you don't starve your sensor you will be fine.

Interesting point. But if you rate the EPIC at 800 you are underexposing, not overexposing. So instead of a "fat or thick negative" you are getting a "thin" one.

 

[Timothy Eaton]

Hi Will,

If you are unsure of where to set ISO, shoot some tests. Create a well lit portrait, so you have flesh tones, allow shadows to fall off on one side of the face, put an evenly lit gray scale in the frame, and spot meter every tone in the frame, writing it all down. Shoot the scene at different ISOs, pop the footage into Red Cine X, output to a well calibrated reference monitor and correlate exposure to ISO and match to the resulting look on the reference monitor. While you're at it, expose an evenly lit gray card at different ISOs. You'll find when you line up the gray card that "native" ISO is indeed 320. But like Evan says, that means nothing, because it doesn't tell you where the sweetest spot of the sensor is. RED designed the MX sensor with greatly reduced noise in the shadows precisely to allow you to set ISO to 800 to hold more highlights.

This is part of a process that you may need to repeat from time to time as you learn more about the camera and the sensor, and as you want to know more about shooting in different scenarios, such as tungsten, etc. This is no different from film. In the end, the only way to know for sure what is going down on film negative is to shoot tests. If you shoot your own tests with your RED, then you will know for yourself what the sensor is recording. Looking for answers from other cinematographers is hopelessly fruitless because you aren't controlling the variables. Someone else may be rating at 320, but putting the histogram in an entirely different place - apples and oranges.

Tim Eaton

 

[Carlos Gonzalez]

Interesting point. But if you rate the EPIC at 800 you are underexposing, not overexposing. So instead of a "fat or thick negative" you are getting a "thin" one.

You are technically right Adrian, but what I meant was to make sure you are properly exposed at 800 and to give it a little extra on top of that. I hope this clarifies it.

 

[Adrian Jebef]

Oh the Alexa has the same issues, maybe not as pronounced on Prores but we routinely expose it down 1-1.5 stops to get the skin tones to look thier best, and the light meter almost never agrees.

Interesting observation. I routinely shoot ALEXA at 400 ISO if recording to ProRes (if ARRIRAW it doesn't matter, it's always gonna be 800). But I do it for the exact opposite reason than with EPIC. ALEXA handles highlight detail and rolloff beautifully so overexposing (by going to 400 ISO) cleans up the image (less noise) while hardly affecting highlight detail (maybe loose 1/3 stop from 95-100% on a waveform). With EPIC you underexpose (by rating at 800 ISO) to "protect your highlight detail".

 

[Timothy Eaton]

Interesting point. But if you rate the EPIC at 800 you are underexposing, not overexposing. So instead of a "fat or thick negative" you are getting a "thin" one.

The concept of a thin negative doesn't really apply to digital imaging - it's apples and oranges. In any event, in terms of exposure, with digital cameras, it's essentially the opposite of color negative. The reason you want a fat negative with film (lowering ISO) is to hold as much detail in the shadows. With digital cameras like Epic, we're more worried about the highlights, which is why the inclination (and RED's advice) is to rate at 800.


Tim Eaton

 

[Adrian Jebef]

Also, I think is is wrong to talk about changing the ISO as introducing "gain." If I recall the discussion by Graeme and company, RED introduces NO analog gain into the system, ever. Any "gain" in post processing is introduced after the A/D conversion and therefore is not electrical gain in the traditional sense. If someone can point me to something that disputes that, please do. But, that is my understanding.

No matter how it all actually works in the chain... ISO or ASA is (for all intents and purposes) Video Gain. It really doesn't matter if it happens during capture, processing, or Post it's still gaining up or down your image.

 

[Adrian Jebef]

You are technically right Adrian, but what I meant was to make sure you are properly exposed at 800 and to give it a little extra on top of that. I hope this clarifies it.

Got it. So like rating the EPIC at 400 ISO?

 

[Adrian Jebef]

Hi Will,

If you are unsure of where to set ISO, shoot some tests. Create a well lit portrait, so you have flesh tones, allow shadows to fall off on one side of the face, put an evenly lit gray scale in the frame, and spot meter every tone in the frame, writing it all down. Shoot the scene at different ISOs, pop the footage into Red Cine X, output to a well calibrated reference monitor and correlate exposure to ISO and match to the resulting look on the reference monitor. While you're at it, expose an evenly lit gray card at different ISOs. You'll find when you line up the gray card that "native" ISO is indeed 320. But like Evan says, that means nothing, because it doesn't tell you where the sweetest spot of the sensor is. RED designed the MX sensor with greatly reduced noise in the shadows precisely to allow you to set ISO to 800 to hold more highlights.

This is part of a process that you may need to repeat from time to time as you learn more about the camera and the sensor, and as you want to know more about shooting in different scenarios, such as tungsten, etc. This is no different from film. In the end, the only way to know for sure what is going down on film negative is to shoot tests. If you shoot your own tests with your RED, then you will know for yourself what the sensor is recording. Looking for answers from other cinematographers is hopelessly fruitless because you aren't controlling the variables. Someone else may be rating at 320, but putting the histogram in an entirely different place - apples and oranges.

Tim Eaton

TE:

This is true. But as you've summarized each scene is different. And we don't necessarily have the ability to pre-test for every scene before we shoot it. Hence, understanding the EPIC and digital imaging as a whole is our best "testing process".

 

[Will Keir]

http://www.reduser.net/forum/showthread.php?63639-EPIC-Native-ISO

Here's a good thread on the topic.