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

[Graeme Nattress]

The definition of ISO by ISO for a raw shooting camera is basically "what the manufacturer recommends", which in the case of Epic is 800. Confusion arises when people look at raw view and find it has a similar amount of gain to 320, but that's because the purpose of the raw view is to allow you to see exactly what detail you've captured in your highlights. The end image is way too dark and too little highlight protection to be useful.

What you perceive as correct exposure is all down to the setting of the development curve, and all curves add some gain to some tones. Because the ISO modifies the curve so that mid-grey is always mapped to the same final image tone, they're all valid ISOs. In each you trade noise for highlight protection (DR is the same for all) so really, the whole concept of "native" ISO goes out of the window and YOU must shoot at the appropriate ISO for your needs. We recommend that you start your ISO at 800 and take it from there.

Graeme

 

[Mark Toia]

The definition of ISO by ISO for a raw shooting camera is basically "what the manufacturer recommends", which in the case of Epic is 800. Confusion arises when people look at raw view and find it has a similar amount of gain to 320, but that's because the purpose of the raw view is to allow you to see exactly what detail you've captured in your highlights. The end image is way too dark and too little highlight protection to be useful.

What you perceive as correct exposure is all down to the setting of the development curve, and all curves add some gain to some tones. Because the ISO modifies the curve so that mid-grey is always mapped to the same final image tone, they're all valid ISOs. In each you trade noise for highlight protection (DR is the same for all) so really, the whole concept of "native" ISO goes out of the window and YOU must shoot at the appropriate ISO for your needs. We recommend that you start your ISO at 800 and take it from there.

Graeme

Thanks Graeme,
This is the first time this has been explained to me properly... and logically.
Im probably the worst offender, I use 320 religiously, so much so that I never change it, even at night. With amazing results mind you.
BUT!!!! After reading this, It sounds like I'm doing this wrong.
Ill shoot my next job at 800 in daylight and see what happens. I'm sure it will be fine.

PS... I'd love a drop in filter or a sensor for one of my cameras that was 25 or 50 iso... I hate having to chuck so much ND on the front, drives me nuts !
Any solution on the horizon for low ISO Graeme? Like the monochrone..? Some obscure camera being made for DAYLIGHT use.

 

[Graeme Nattress]

Mark, if you get great looking images you're not using the camera wrong. The only issue with setting camera to 320 is just "watch those highlights", so if you keep them in control you'll probably be getting very similar raw code values to if you'd used ISO800. All that matters is the raw code values - what ISO setting at is irrelevant as long as those raw code values are good. Our advice on 800 is to ensure people have a good starting point to get those code values.

Graeme

 

[Mark Toia]

Mark, if you get great looking images you're not using the camera wrong. The only issue with setting camera to 320 is just "watch those highlights", so if you keep them in control you'll probably be getting very similar raw code values to if you'd used ISO800. All that matters is the raw code values - what ISO setting at is irrelevant as long as those raw code values are good. Our advice on 800 is to ensure people have a good starting point to get those code values.

Graeme

Understood... and a good idea to have a little bit of high end protection for the not so cautious opertaors.

So... How about a 50asa camera. I remember Jim and Jarred in the past talking about internal ND's... or something like that. I'm keen to help you feild test if something is in the pipeline.

Thanks Graeme. again.

 

[Gunleik Groven]

Deanan mentioned a replaceable olpf with built in nd's.

Has not heard about it since he left.
Nd9, methinks. Which would get us to the 100 level.

 

[Mike Kushner]

definitely 320 ASA. easy to determine. just set the proper exposure to your eye on ASA 800 while not viewing RAW, then toggle the raw button. When the image gets a little too dark for proper shadow exposure, you know the native, raw ASA is not 800.

 

[Lauri Kettunen]

Compare, we could also try to specify the "native" power of a microwave oven by comparing its heating up times to traditional electric ovens. For this reason I would say ISO is already part of history, but it's still there to smoothen the transition from the old tradition to the world of completely new equipments.

 

[Terry VerHaar]

definitely 320 ASA. easy to determine. just set the proper exposure to your eye on ASA 800 while not viewing RAW, then toggle the raw button. When the image gets a little too dark for proper shadow exposure, you know the native, raw ASA is not 800.

Yeah - cuz Nattress doesn't know much about RED. LOL

 

[Mike P.]

Being that it's RAW, doesn't it make more sense to just watch the goalposts regardless of the ISO setting? I mean, if your goalposts are empty, then it doesn't matter what the ISO is, nothing will be clipped/blown or crushed/noisy and you can place the mid-tone anywhere you want via your curves... Right?

I've been in the habit of shooting at 800 and almost automatically lowering it to 320 in RCX and using a curve to get the mids back to where I want them (~40ire)... Everytime I read a thread like this I starting to doubt this process though.

EDIT: Also, has anyone used the "Film10" look in the default directory (it ships with RCX.) It's RC2, but that's easy enough to change.

 

[Ketch Rossi]

Hahahahahahaha

But we like and dislike in an image vary. An exposure i like, you may dislike. I may like the noise, you may not. And as Graeme has said a number of times, "native" iso in the digital domain is dictated by the manufacturers.

A sensor may have a technical measureable midlevel. Which would dictate a certain iso.
But
As that may not be the point where you get the best technical image, that doesn't make much sense to stick to diehardly.

Many digital cameras look not so nice out of their sweetspot, when you go too much over or under. And that fat spot is not allways exactly where the technical measureable iso should be.

I never bothered to measure the iso, but the ones who have done seem to agree on a number around 200.

That is fine.
It is still not a good plan to shoot at 200, and if you go bellow 320 you are really just confusing yourself. Add wb and clamping of channels into the soup, and the answer is: you want headroom and contrast...
Thus underexposing is the practical advice, to make a nice rolloff in both ends of the spectre.

Epic does that more elegantly than any other camera i know of.

I sometimes lower the iso slightly for some dp's though, to force the technical exposure a bit up. Our eyes and what we look for in images vary by a large margin. But in the end it is all about learning to know the tool as well as dp's used to know their stocks. THEN you can set the iso to whatever and get excellent results...

I know extremely well my camera, and since the very first images, now part of the 700 Reel, I for one, know well that the Native ISO is 800, and shoot accordingly.

What I meant as EXPOSURE been an important player, is to detail the importance of the EXPOSURE, and there is on likes about, you either Expose properly or you don't, if you do and shoot with the proper ISO then you get a great image, if you use the right ISO and don't Expose properly then you will get an image with either Clipped highlights or you are bringing in NOISE.


There is no liking of Exposure, you should always Expose properly, then with a pristine and properly Expose image you can create any looks you want in post.

 

[Adrian Jebef]

The definition of ISO by ISO for a raw shooting camera is basically "what the manufacturer recommends", which in the case of Epic is 800. Confusion arises when people look at raw view and find it has a similar amount of gain to 320, but that's because the purpose of the raw view is to allow you to see exactly what detail you've captured in your highlights. The end image is way too dark and too little highlight protection to be useful.

What you perceive as correct exposure is all down to the setting of the development curve, and all curves add some gain to some tones. Because the ISO modifies the curve so that mid-grey is always mapped to the same final image tone, they're all valid ISOs. In each you trade noise for highlight protection (DR is the same for all) so really, the whole concept of "native" ISO goes out of the window and YOU must shoot at the appropriate ISO for your needs. We recommend that you start your ISO at 800 and take it from there.

Graeme

Hmmm. For someone with a technical background these answers seem a bit vague. Let's just cut thru the nonsense and rephrase this Thread's question as "What is the native sensor sensitivity expressed as ISO".

Correct me if I'm wrong but you seem to be saying:

1 - ISO for all digital cameras is a "recommendation" not an absolute

2 - Raw View = 320 ISO sensitivity = 0 Gain

3 - Shooting at 320 ISO will give you a "dark image with no highlight protection" (????)

4 - Correct exposure is determined by the "development curve". (What is this? RedLogFilm?)

5 - Mid-Grey in the scene is always mapped to the same tone irrespective of the ISO setting. (this would imply that there is a finite, native sensor sensitivity) (which is at odds with native ISO being a recommendation and not an absolute)

 

[Terry VerHaar]

Hmmm. For someone with a technical background these answers seem a bit vague. Let's just cut thru the nonsense and rephrase this Thread's question as "What is the native sensor sensitivity expressed as ISO".

Correct me if I'm wrong but you seem to be saying:

1 - ISO for all digital cameras is a "recommendation" not an absolute

2 - Raw View = 320 ISO sensitivity = 0 Gain

3 - Shooting at 320 ISO will give you a "dark image with no highlight protection" (????)

4 - Correct exposure is determined by the "development curve". (What is this? RedLogFilm?)

5 - Mid-Grey in the scene is always mapped to the same tone irrespective of the ISO setting. (this would imply that there is a finite, native sensor sensitivity) (which is at odds with native ISO being a recommendation and not an absolute)

I believe you are dead wrong on #5.

http://www.red.com/learn/red-101/exposure-with-red-cameras

And, as for #2, there is never any "gain" applied to the captured image.

 

[Adrian Jebef]

I know extremely well my camera, and since the very first images, now part of the 700 Reel, I for one, know well that the Native ISO is 800, and shoot accordingly.

What I meant as EXPOSURE been an important player, is to detail the importance of the EXPOSURE, and there is on likes about, you either Expose properly or you don't, if you do and shoot with the proper ISO then you get a great image, if you use the right ISO and don't Expose properly then you will get an image with either Clipped highlights or you are bringing in NOISE.


There is no liking of Exposure, you should always Expose properly, then with a pristine and properly Expose image you can create any looks you want in post.

Ah, ha! I'd put forth that a "correct exposure" is being able to light your scene in such a way that all of the important details (read highlight and shadow) are CAPTURED by the sensor of your camera and not clipped. The only way in which we will know what RANGE we can light a scene to is to KNOW what range our camera is capable of handling. This range has a midpoint (a place where there is an equal distribution of exposure range above and below 18% Grey). This midpoint is commonly referred to as a sensor's "native sensor sensitivity" and more commonly called it's "native ISO or ASA".

 

[Graeme Nattress]

ISO for RAW (and only RAW) cameras is a recommendation.

RAW view has a gain and curve applied to show you what's going on in the highlights. ALL development ISOs have neutral gain because we don't change the analogue gain on ISO. It's all in the digital development curve.


ISO800 gives you 4.5 stops above mid grey, ISO320 therefore gives 3.2 stops above mid grey.

Correct exposure is determined by the scene.

Mid grey in the scene for any given ISO is always mapped to the same point in the image post development curve.

Graeme

 

[Gunleik Groven]

I know extremely well my camera, and since the very first images, now part of the 700 Reel, I for one, know well that the Native ISO is 800, and shoot accordingly.

What I meant as EXPOSURE been an important player, is to detail the importance of the EXPOSURE, and there is on likes about, you either Expose properly or you don't, if you do and shoot with the proper ISO then you get a great image, if you use the right ISO and don't Expose properly then you will get an image with either Clipped highlights or you are bringing in NOISE.


There is no liking of Exposure, you should always Expose properly, then with a pristine and properly Expose image you can create any looks you want in post.

Ketch
That was not an attack on you.
I didn't imply that you do not know your camera, just that there is no other right way than the one that gives youthe imageyou are aiming for...


I love how the epic blows out and can sometimes use the noise artistically.
So, technically i am happy to under- and overexpose from a purely technical POV, if that gives me the reslt I want.

Thing is to be in controll. Not discussing rights and wrongs as absolutes.

From a purely technical POV, there are things to be said as to how yo can get a fat, lownoise image.
And i feel pretty comfortable. In being able to do that.

But from an aesthethical POV, that is. Often NOT the image I want.
Hahahaha

So i very often deliberately break the technical premises, to get what I want.

And I feel I did my exposure"right" when I am happy with the result.

THAT was my point.

Not to. Attack you.

 

[Adrian Jebef]

I believe you are dead wrong on #5.

And, as for #2, there is never any "gain" applied to the captured image.

GM is discussing ISO as a metadata setting and not as a base sensor sensitivity. That is why no matter what you set your ISO to on the EPIC the camera only records a FINITE coded value for your 18% Grey card in the scene. If you shoot EPIC at 320 your grey card will be at mid-grey once openned in RedCine. If you shoot 800 your card will be a stop dark. The inverse is also true, the EPIC always "processes" tone-mapped 18% Grey (in camera mid-grey not scene mid-grey) to the midpoint of its ISO-dependent gamma curve. The EPIC "rescales" exposure data when you change ISO but it cannot rescale scene exposure. Therefore, understanding a camera's native sensor sensitivity is important.

Agreed on #2 (practically, not technically). There is no Gain applied when the sensor first captures the scene and records a R3D. Which makes understanding native sensor sensitivity even more important because this is exactly where your image is the cleanest and most "noise-free". Raw Check is defined by RED as a representation of what is actually being recorded in the R3D. If Raw Check equates to 320 ISO then the native "raw" sensitivity of the EPIC can be expressed as 320 ISO. Otherwise known as 0 Gain in the video world (which we happen to still be in).

 

[shashbugu]

i guess we learn something new everyday,


ISO 800 should be your starting point.
Got it.

 

[Adrian Jebef]

ISO for RAW (and only RAW) cameras is a recommendation.

RAW view has a gain and curve applied to show you what's going on in the highlights. ALL development ISOs have neutral gain because we don't change the analogue gain on ISO. It's all in the digital development curve.


ISO800 gives you 4.5 stops above mid grey, ISO320 therefore gives 3.2 stops above mid grey.

Correct exposure is determined by the scene.

Mid grey in the scene for any given ISO is always mapped to the same point in the image post development curve.

Graeme

Aren't ALL current (CCD / CMOS) digital motion cameras "raw" cameras? Not every camera can record RAW but every camera "sees" light in the same black & white, linear way (read RAW). Every camera must go thru RAW in one way or the other before it can display a "proper" image to our eyes. The ALEXA can record both gamma-corrected video (ProRes) and RAW (ARRIRAW). Surprisingly (or not...) there is little difference between the two when the camera is exposed at the "recommended" 800 ISO (ARRIRAW usually gives you a slight increase in DR and image resolution/sharpness due to uncompressed recording). Most DP's, AC's, and DIT's that I know are comfortable labeling the ALEXA at "natively 800" when shooting ProRes or ARRIRAW.

Concerning Raw Check, ISO, and the "development curve": what's the difference between analogue and digital "Gain". Aren't we adding noise either way?

If 800 ISO gives us 4.5 Stops above mid-grey that leaves 9 Stops under (as RED claims 13.5 Stops of DR). So this seems to imply that if we expose at 1600 ISO (?) we would arrive at an equal distribution of exposure latitude above and below middle-grey (6.75 Stops above and below).

Is the EPIC's native sensor sensitivity analogous to 1600 ISO?

 

[shashbugu]

Aren't ALL current (CCD / CMOS) digital motion cameras "raw" cameras? Not every camera can record RAW but every camera "sees" light in the same black & white, linear way (read RAW). Every camera must go thru RAW in one way or the other before it can display a "proper" image to our eyes. The ALEXA can record both gamma-corrected video (ProRes) and RAW (ARRIRAW). Surprisingly (or not...) there is little difference between the two when the camera is exposed at the "recommended" 800 ISO (ARRIRAW usually gives you a slight increase in DR and image resolution/sharpness due to uncompressed recording). Most DP's, AC's, and DIT's that I know are comfortable labeling the ALEXA at "natively 800" when shooting ProRes or ARRIRAW.

Concerning Raw Check, ISO, and the "development curve": what's the difference between analogue and digital "Gain". Aren't we adding noise either way?

If 800 ISO gives us 4.5 Stops above mid-grey that leaves 9 Stops under (as RED claims 13.5 Stops of DR). So this seems to imply that if we expose at 1600 ISO (?) we would arrive at an equal distribution of exposure latitude above and below middle-grey (6.75 Stops above and below).

Is the EPIC's native sensor sensitivity analogous to 1600 ISO?

Dude! don't confuse things. GN has clearly stated the ISO 800 should be the way to go in most situations Alexa's type of 800 ASA is a different story, different sensor, different color science. EPIC is 800 and that is that. Spending time answering your question ridiculous 1600 ISO question is a waste of time.

 

[Ian Laurie]

ISO for RAW (and only RAW) cameras is a recommendation.

RAW view has a gain and curve applied to show you what's going on in the highlights. ALL development ISOs have neutral gain because we don't change the analogue gain on ISO. It's all in the digital development curve.


ISO800 gives you 4.5 stops above mid grey, ISO320 therefore gives 3.2 stops above mid grey.

Correct exposure is determined by the scene.

Mid grey in the scene for any given ISO is always mapped to the same point in the image post development curve.

Graeme

Hey Graeme, Thanks for all your input. I am pretty sure i understand what you are saying. Out of curiosity, I still own an original M Red One, would going to say 640 (which seems to be about the heavy noise limit) basically just preserve the highlights? does the same principle apply only with a higher noise floor than the MX? Just curious. I have always shot everything in RAW view so never paid much attention to the ISO and, yes watched my highlights, but may be willing to give higher ISO's a try if there is something worth trying.