What are the pros/cons of shooting just with the RAW settings of the camera?

[Fernando Tufiño]

I´ve been using my Scarlet for a while and lately i´ve been trying to shoot with the "Raw Check" always on and just exposing that image right, so I could practice color grading and understand what I can do with the image a little bit more.

My question is, basically, is this the most efficient way to work with Red?

Also, after doing some tests with a lightmeter, a 18% grey card and using the "video" function for correct exposure (properly lighten with tungsten lights in a film set, 4k, 25fps, 1/50, 3200K, ISO 800) I found that the true native ISO of my Scarlet is 320, but then I turn the Raw Check mode on, and I found a significant drop. Doing the same test I found that the native ISO with Raw Check mode on is 160!!!

160 ISO... does this means what I think? Can someone please verify this?

I performed this tests side by side with a Red One and I got the same results, slightly better dynamic range with the Scarlet.

I am a little concerned of how much gain I´m actually giving to the image when not using "Raw Check" mode.


Please respond if you have helpful information. Thanks in advance.

 

[Matthew Scott]

If you set your camera to 320 ISO, 5000kelvin and no picture style with Red Log as the color space, it will look identical to the RAW mode. It's not 160...it's 320

 

[Alex Rawet]

Have a read of this thread:

http://www.reduser.net/forum/showthread.php?86485-Opinion-POLL-EPIC-native-ISO-800-or-ISO-320

Graeme's responses help explain what is going on when you look at the RAW mode.

 

[Webster Miller]

Another discussion/explanation on this can be found on RED's website at http://www.red.com/learn/red-101/exposure-with-red-cameras


Hope this helps.

 

[Fernando Tufiño]

Thanks Alex for the info. I´ll copy and paste Graeme´s responses in case someone else wants to read them, because I think it´s very important piece of information:


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



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

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[Fernando Tufiño]

More on this:

"Not every camera can record RAW but every camera "sees" light in the same black & white, linear way (read RAW). " - you need to take that up with ISO, which only specifies equations for shooting JPEGs on DSLRs, and for RAW shooting specifies that you "go with the manufacturer suggestion".

" what's the difference between analogue and digital "Gain". Aren't we adding noise either way?" - digital gain doesn't add noise, but it can make noise in the image more visible. Analogue gain adds noise and also removes highlight detail through clipping. As all reasonable (ie ones that make a viewable image) development curves add some gain to some code values, to suggest that the one with the least gain is somehow native is absurd as it would produce an ugly image and that helps nobody.

Yes ISO1600 would balance above and below stops more evenly but we feel that ISO800 is a more appropriate starting point for people shooting the camera. I guess that takes us back to the ISO recommendation....

Ian, Adjusting ISO doesn't effect noise or noise in any way, but it does help you visualize exposure. Exposing to avoid clipped highlights is like a form of ETTR (expose to the right) and it's a valid method. If you ETTR and the image appears too dark in the mid-tones for comfortable viewing, up the ISO. If you think the ISO is too high for your noise tolerance, open up your exposure more.

With respect to 18% grey and code values.... Say you shoot a scene at ISO800 and you have your aperture set so that a grey card appears to be about 45% in the developed image and now you change ISO to 400, and open up your aperture a stop to compensate that grey card will still be at 45% in the developed image.

Adam, At ISO800 you have more stops below mid grey than above - everyone has a different noise tolerance, we suggest ISO800 as a starting point. We don't use term native ISO as it doesn't really make sense in a fixed analogue gain camera, and even in DLSRs where you have combos of both digital and analogue gain it gets hyper-confusing.....

Graeme


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Yes a true raw image would be unusable and unviewable. I have such a feature in my R&D app should I need to look at raw code values in their native state, but it's not practical for any other purpose. You can think of the raw view as a pure curve (no tonal adjustments), neutral colorimetry and negative gain to allow you to see the highlights without any compression.

Graeme


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[Fernando Tufiño]

And the last bit of info on the same:

I think this needs to be cleared up, RAW view (a legacy name from the R1) is probably responsible for most of the confusion in this thread.

1. RAW View is not truly RAW! It's a Gamma/Color space application that is flatter, less saturated and nominally ISO 320
2. RAW View is there for you to quickly see what detail you have in your highlights, not to use as an exposure reference for any mid tones or shadows.
3. RAW View does NOT show actual sensor data, that is linear and B&W and unusable.

By setting the Epic to ISO 800 you are essentially applying a viewing LUT (Meta data) to the image that gives you the best balance of highlight exposure and noise floor.
Regardless of the ISO set on the camera (or which camera) if you use the ETTR method you will end up with the best possible exposure.
My only caveat to that is that on pretty much every digital camera skin tones look best exposed down a 1/2 stop or so.

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OK - there is NO native ISO, only the correct exposure for any scene which will entail the correct ISO setting to put mid grey in the middle of the developed image. We (as in RED) recommend on MX and Epic a starting point of ISO800 for your use. That doesn't mean it's the right ISO for any shot, but one we've found works in a wide variety of circumstances.

To me native ISO only makes sense as a statement in a camera with destructive analogue or digital gain. We don't do destructive gain, so no concept of native ISO makes sense.

Graeme

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Yes, some cameras will, even in RAW, bake in digital gain as well as analogue gain (which you expect to get baked in). As Blair notes it doesn't stop the signal being linear, but it does diminish the highlight ability (or if negative gain is baked in) data precision.

Graeme

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Originally Posted by Yousuf Abbasi
I guess it all boils down to the definition of the word "native." What is it?

If GN is calling "native" the suggested starting point because its gives an pretty good range of highlights and shadow details, then it's not really a technical definition. But it supports why people use ISO800.

If others are calling "native" the ISO the point at which they "visually see" the same exposure when switching to the RAW view, then it's more technical of a definition. And it supports why people "say" ISO320 is native but some still shoot the camera at ISO800 on most occasions.

I don't know why it all matters, anyway. As a rule of thumb, I've always shot ISO800, ETTR, then picked up shadow details in RCX by sliding back to ISO320. It has worked well enough to produce nicely exposed, clean images. I'm afraid that if I set the camera to ISO320 and exposure for that, I have less latitude in post. This is not scientific, just based on trials and errors. In the end it gets me where I want to be.




What is "native" indeed. I don't really think the RED cameras have a "native" ISO, but they do have a range of good ISOs you can use, all with the same dynamic range. Basing "native" off the raw view is incorrect because the raw view is just a "raw-ish" view designed to show what people wanted from a raw view - a locked-off image with all the highlight detail there.

You know, sometimes it's "whatever works to get the image" and there's many different ways to get to a superb image.

Graeme


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"Judging from this poll is leaning more towards 320 yet still people are insisting on 800." - problem is that the people who insist on a) stating there's a native ISO when there really isn't, and b) that it's 320 are not the people who designed the camera. If there was a nice simple happy answer I'd give it to you, but there's not because the camera is happy working over a wide range of ISOs, all of which have the very same dynamic range, all of which suit different scenes better than others due to a different distribution of highlight and shadows range around mid grey. The manufacturer recommends you start with ISO800 for a reason, and that is we've practically found it a very good place to start.

Graeme


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Originally Posted by roryhinds
But surely even if the camera and post software can happily work with different ISO settings the amount of light being captured by the sensor will remain the same amount of light being captured by the sensor and the only things that will effect the light captured by the sensor would be Aperture and Filters in front of the lens.



Yes, that is correct, which is why the ISO recommend on a RAW camera the manufacturer decide on the ISO, which we have, and that's where the 800ISO comes from as a practical recommendation. I really don't like to say people are wrong, but I don't think you're right by stating it's a 320 sensor, not least as that meaningless as a raw image doesn't have an ISO sensitivity the way film does because the development curve is very flexible and you get valid developments over a very wide range, and none delivers more or less dynamic range than the others. If we have a variable analogue gain stage some gains would deliver more DR than others and you could call the one or ones that deliver the most "native", but really, the concept of "native" doesn't really make much sense here.

Graeme


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AFAIK there's no defaulting to 320 for RLF. I'm not sure where you're getting that from. As for the rest, go back and read my comments in this thready.

What you're saying about the sensor is not how sensors work. Sensors don't have an ISO rating. Sensors are not film. Sensor data + development curve produces an image, and we have a digital equivalent of ISO that is valid over a range of values. Think, like Gunleik suggests above that each one of those ISOs is a different stock with different capabilities if you want.

Graeme


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Originally Posted by Ian Laurie
Got a feeling this thread is headed for closure. You have Graeme, with firsthand knowledge of both the sensor and the magic pixies telling you that, if for some reason you need a set iso, the recommendation of Red and himself is 800. The fact that he can explain more is beneficial to our understanding, but if this was any other company his response would have been 800, with no other comment. However you have pushed and pushed for a technical answer and he has stated that technically, there is no native ISO on a digital camera. Which explains why some like to expose knowing exactly where they may have problems (the 320 crowd, me included) and others prefer 800 because it allows them to worry less about clipping and work in the way they are most comfortable. you wanted an answer ( i did too) he gave it too you, and now your upset because not only was it not an answer you wanted, it wasnt even one you ( or I) expected. Accept it, if you like 800 use it. if not don't. I personally am gonna take graeme's information to try some new things outside of my comfort zone. yeesh... rant over.




A digital camera that can record a RAW image does not have an ISO because the function of ISO is technically in image processing not acquisition. This is because a RAW image is fundamentally considered to not be an image (yet). ISO is metadata when dealing with a RAW workflow. It cannot be burnt in so it cannot be considered native. Graeme is correct. Any ISO setting can be considered a valid one and they are all equal in that respect. However, that does not mean that the camera's sensor itself does not have a base exposure sensitivity index.

So semantics = confusion. Clarity = re-clarification:

"What is the EPIC's native sensor sensitivity or exposure index?"

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We're putting out new tutorials all the time, so I'll ask that our team look at ISO, but http://www.red.com/learn/red-101/exp...th-red-cameras will get your started.

There is indeed no ISO setting that is "more native" than any others because we don't burn in digital gain and we don't do analogue gain.

Graeme


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[Nick Pasquariello]

The most important thing you can know about shooting on Red, or on any camera that shoots raw, is that ISO, Kelvin, Tint, Colorspace, and a few other things are NOT BAKED IN. This means the following:

If you shoot at 2000 ISO, you didn't capture the image at 2000 ISO. You captured the exact same image you should have captured if you shot at 250 ISO using the same Apperture, Lights, Lens, etc. If all you change is the ISO, or the Kelvin, or the Tint, you DID NOT CHANGE WHAT DATA YOU RECORD.

So, if you are saying "What ISO do I have to shoot at to get a good image?" you're looking at it wrong. A better question is "What ISO should I be viewing to get the best representation of what the image sensor is actually catching?"

The answer to that question is somewhere between 320-800 depending on who you ask. There are reasons to look at ISOs outside this range, but in an ideal scenario, limit to within that range.

 

[Elsie N]

Being a simple man, I'm not too prone to over-thinking things. My assumption is that if you change ISO you will get a different clip point in RAW view. (If I'm wrong, someone please correct me) For that reason, I generally leave ISO at 800 for summer shooting and later when the seasons change and the sun is not so intense, I change to 640 or in the dead of winter, 500 because I will have more information in the lower range that I want to capture to "feel" the season. I use the RAW view to ETTR, especially if panning or changing positions. I just want to know where the histogram maxes out without clipping. If I'm locked off, I'll switch out of the RAW view. I get images that I find satisfactory doing this.

 

[Fernando Tufiño]

Thank you, you were all very helpful!

 

[Aria Khosravi]

Being a simple man, I'm not too prone to over-thinking things. My assumption is that if you change ISO you will get a different clip point in RAW view. (If I'm wrong, someone please correct me) For that reason, I generally leave ISO at 800 for summer shooting and later when the seasons change and the sun is not so intense, I change to 640 or in the dead of winter, 500 because I will have more information in the lower range that I want to capture to "feel" the season. I use the RAW view to ETTR, especially if panning or changing positions. I just want to know where the histogram maxes out without clipping. If I'm locked off, I'll switch out of the RAW view. I get images that I find satisfactory doing this.

I think the way that you're exposing is entirely correct, however, changing your ISO should not change anything at all in "RAW" view. As Graeme has said, RAW view is just a different LUT with the ISO set to 320. So whatever ISO you have will be set to 320 for RAW view. This was all said in the above posts, but again, the cameras are not like film. You are not changing the sensitivity of the sensor by changing the ISO. You are simply interpreting the information differently. Personally, going with RED's recommendation, even though some people insist that the folks who designed the camera are wrong about how it works, I start off with ISO 800 to expose. I make sure no highlights are clipping. A bit of clipping in the shadows is fine for most shots. It's probably going to get crushed down later anyway. Even RED says that you can probably get away with half of the left goal post clipping. Later on in post, I'll have them re-adjust using the ISO controls if we feel that the exposure is a little more than what we were going for. Using this method, we never have to adjust ISO upwards, just downwards if things are too bright. But we have all of the highlight information and shadow info that we could want, so we can adjust without anything clipping. I don't think, personally, that it's okay to start at 320. I feel like some of the folks who do this haven't sat down and tried shooting tests both ways to see the effect that each method has. If you start at 320, you can only safely adjust upwards later. If you were exposing as if 320 was "native," then that means that you will probably overexpose if you adjust upwards, so you're pretty much stuck at 320. I understand also that there are some people in the 320 crowd (not all of you) who ignore the goal posts entirely. They just keep going if the histogram looks good, even though the RAW goal posts say that 1/3 of the highlights are clipped. If you actually want to know what is and isn't clipping, just look at the goal posts by the histogram and use exposure check mode.

And one last note, to give a bit of an example. If I'm shooting a scene that's supposed to look dark, but with detail in the darkness (like how our eyes perceive darkness in real life), this is when I use 320. I will still start with 800 to get a good idea of what is and isn't clipping, and I expose to the right aggressively here. Then I drop it down to 320. Now there are no clipped highlights, and I have a low key look, but there is plenty of detail visible in the shadows, without noise covering it up. If I were to expose so that the highlights were slightly clipping, like, say a kicker on the side of someone's head is blowing out, then we have issues. When you drop this down to 320, all of the information that didn't clip adjusts as you would expect. However, the clipped information stays exactly where it started: clipped! Thus, you've further decreased the 'filmic' roll-off in the highlights, and replaced it with a strictly 'digital' look.

Now everyone's going to curse me out for being so ignorant and not defaulting to ISO 320. If you plan on doing this here, please remain calm and try to logically explain your viewpoint. As much as I hate starting arguments, I kind of want to start a simplified thread with tests demonstrating the difference I've found between each exposure method, to see if that helps anyone or if I'm just an idiot. As Graeme said, part of the issue is that people are missing the fact that the new RAW view (in contrast to the old RED One version) has negative gain and is not supposed to be a representation of what the sensor is seeing.


TL; DR Ignore me, everyone listen to Graeme, he's pretty much the guy who makes this camera work the way it does, I'd trust him more than anyone else