“Expose to the Right” & relation to ISO Invariance

[Jack Hogan]

I totally agree that if you are taking the trouble to ETTR to maximise informatoin then why not go the whole hog and use base ISO, but that is NOT the same as saying base ISO is a critical part of ETTR.

I hear you spidermike, but in this thread the context is ISO invariant cameras.  For a given exposure they maximise scene information captured at base ISO.  So with an ISOless camera you should attempt to ETTR at base ISO.

Jack

[digitaldog]

I'm not a native English speaker, but I believe that "getting confused" is not the same as "he is confused", or "he is becoming confused" and certainly not the same as "he says he is confused". But feel free to correct my interpretation of the English language, I'm eager to learn.

You don't have to be a native of the English language to see that the first person to use the word 'confused' was you. In relationship to the OP who isn't confused but asking for clarification.

[Bart_van_der_Wolf]

You don't have to be a native of the English language to see that the first person to use the word 'confused' was you. In relationship to the OP who isn't confused but asking for clarification.

And that makes me speak for others? Now you've got me confused ...

Cheers,
Bart

[digitaldog]

And that makes me speak for others? Now you've got me confused ...

Yes that much is clear.
Do I really have to connect the dots for you? You brought up the OP and the term about him being confused when he isn't confused and by suggesting he is, you're doing him a disservice.

[AlterEgo]

So with an ISOless camera you should attempt to ETTR at base ISO.

but first again you also need to know what your converter (along with camera profiles, specifically in ACR/LR case) is doing behind the scenes with exposure

[Bart_van_der_Wolf]

Yes that much is clear.
Do I really have to connect the dots for you? You brought up the OP and the term about him being confused when he isn't confused and by suggesting he is, you're doing him a disservice.

There you go again. I never suggested that. What I did suggest is that there were half truths being told, which might confuse anybody (and I do  know the distinction between anybody and everybody, before you start an OT attack about that).

A half truth like ISO 800 being better than ISO 100, without pointing out the non-ETTR exposure and the non-ISO-less camera used as an example. Oh wait, it was you who brought up that example. Could that explain the diversion tactic by suggesting that I pretended to speak for the OP? Never mind, it is clear to me.

Others have tried to pull off such an 'example' at other occasions, and I've responded to those as well with factual information. So don't take it personal, unless you want to, feel free to do so. We can then discuss what concept you were trying to get across with that example, and how it was relevant to the OPs question which you seem very concerned about. Looking forward to an on-topic discussion.

Cheers,
Bart

[Bart_van_der_Wolf]

but first again you also need to know what your converter (along with camera profiles, specifically in ACR/LR case) is doing behind the scenes with exposure

Indeed, there is a risk of Hue twists getting in the way in the ACR/LR case. Others have reported concerns about Capture One as well, but I've not experienced that myself. Boosting even to three or four stops over an underexposure doesn't change the colorbalance a bit, maybe some isolated colors I have missed?

Cheers,
Bart

[digitaldog]

There you go again. I never suggested that.

You indeed didn't suggest, you said so. 
Even Jack asked you rather clearly: Why would he be getting confused? 
So I'm not alone.
We're getting OT like the other discussion you have posted within today (Adobe conspiracy theories). I don't have the time to address your assertions.

[Jack Hogan]

but first again you also need to know what your converter (along with camera profiles, specifically in ACR/LR case) is doing behind the scenes with exposure

If by that you mean that you should not be using LR for anything but a quick conversion, I agree  On the other hand I am just referring to capturing the best image quality possible.  How you render it to be most pleasing is another matter.

Jack

[AlterEgo]

If by that you mean that you should not be using LR for anything but a quick conversion, I agree  On the other hand I am just referring to capturing the best image quality possible.  How you render it to be most pleasing is another matter.

Jack

what I am saying is that for example ACR/LR not only might have exposure correction dependent twists in some camera profiles, but they might apply different hidden exposure corrections (not to mention again that process 2012 exposure correction is not linear in ACR/LR) based on the nominal ISO (different ISO = different corrections) for the same camera model... so any ETTR application shall take into consideration the tools that deal with raw file afterwards before you decide how you are going to expose - like the ISO it is not part of the exposure, but it is a part of your decision how to expose (before it starts) because it affects the processing when it (exposure) ends.

[Dave Ellis]

I just had another read of Michael's article of 2011 on ETTR and it re- inforced my view that you only get benefit from ETTR if the dynamic range of the scene is less than that of the camera. In this situation, ETTR results in over exposure which is then reduced in pp thus reducing the noise. it is sort of equivalent to shooting with a lower ISO than base ISO.

You will therefore get most benefit from ETTR if you shoot at base ISO where the dynamic range is highest.

An ISO less camera will generally have better dynamic range at base ISO than one that isn't ISO less, for a given pixel size. Thus it should be more likely that you can get some benefit from ETTR with an ISO less camera at low ISO.

Dave

[Jack Hogan]

what I am saying is that for example ACR/LR not only might have exposure correction dependent twists in some camera profiles, but they might apply different hidden exposure corrections (not to mention again that process 2012 exposure correction is not linear in ACR/LR) based on the nominal ISO (different ISO = different corrections) for the same camera model... so any ETTR application shall take into consideration the tools that deal with raw file afterwards before you decide how you are going to expose - like the ISO it is not part of the exposure, but it is a part of your decision how to expose (before it starts) because it affects the processing when it (exposure) ends.

I hear what you are saying, but what we are talking about here is really just 'brightening' by linear multiplication before applying all the other adjustments - pretty basic stuff, as described in the earlier link: most well behaved converters do this as a matter of course (I am familiar with Nikon NX converters, RT, DCRAW and ACR).  The only converter I know that insists on introducing all sorts of secret camera specific 'twists' is Adobe's, presumably in order to keep things as simple as possible for its users. Nothing wrong with that.  But until they fix it perhaps it should not be used when attempting to achieve advanced performance.

If this sounds harsh, consider that properly implemented ETTR is the only 'correct' exposure when the objective is maximum IQ.  Many cameras are able to approximately meter this ideal exposure in-camera today (e.g. Nikon's Matrix/Highlight-Weighted metering with Auto ADL).  ACR/LR on the other hand incorrectly treat those perfectly exposed images as underexposed/overexposed, possibly introducing weird 'twists' while rendering them.  A perfect case of the software not keeping up with advances in the hardware.

Jack

[Bart_van_der_Wolf]

You indeed didn't suggest, you said so.  
Even Jack asked you rather clearly: Why would he be getting confused?

To which I gave a technical answer, and a link to an external source, to explain my view.

So I'm not alone.

?? I'll let Jack speak for himself if he feels inclined.
I do not need people to agree with me, although they might, if my explanation makes sense to them, or they may add another viewpoint that makes sense to me. One can only learn and benefit from such an exchange of views, or at worst agree to disagree.

We're getting OT like the other discussion you have posted within today (Adobe conspiracy theories).

Ah, that's another allegation you came up with, in reaction to a direct remark I made to another poster with a smiley. So it is that personal for you, that remarks I make to other people in other threads affect your reaction in this thread about a different subject? Amazing.

I don't have the time to address your assertions.

Nobody is forcing you (or me) to respond to anything, assertions or not, so no problem if you do, no problem if you don't. When I'm asked a direct question (especially when it helps a discussion to progress) I'll try to answer, if time allows. So without further questions, we'll leave it at that then.

Cheers,
Bart

[mouse]

what I am saying is that for example ACR/LR not only might have exposure correction dependent twists in some camera profiles, but they might apply different hidden exposure corrections (not to mention again that process 2012 exposure correction is not linear in ACR/LR) based on the nominal ISO (different ISO = different corrections) for the same camera model... so any ETTR application shall take into consideration the tools that deal with raw file afterwards before you decide how you are going to expose - like the ISO it is not part of the exposure, but it is a part of your decision how to expose (before it starts) because it affects the processing when it (exposure) ends.

This may be a bit too much of a diversion from the thread topic, but I feel it is better addressed here than starting another thread:

May I ask for some clarification? 
Are you saying that the (non-linear) behavior of exposure correction in LR/ACR varies depending on the ISO value used for the exposure (as determined from the exif data)?  Alternatively is the behavior dependent on the image values themselves (as influenced by exposure as well as ISO)? 
In either case, how does this information influence your decisions prior to exposure? 
I can see how it might influence one's choice of the camera profile used in that raw conversion software, or even the choice of raw conversion software itself.

[AlterEgo]

Are you saying that the (non-linear) behavior of exposure correction in LR/ACR

it is what process 2012 brings... so exposure correction for +5 stops in ACR/LR is not exactly the same as dialing EV+5 (including increasing ISO by 5 stops) in camera and feeding that to ACR/LR... the closer to clipping you are the more compression exposure correction in PV2012 does... granted with "ETTR" you most probably will be going backwards (pulling, not pushing), that helps (twists if present in profile still matter)

varies depending on the ISO

hidden exposure correction done by ACR/LR code might be different for different nominal ISOs, that part depends on ISO only (but then see above about non linear nature of exposure correction in PV2012) - for example with Fuji raw files.

[bjanes]

what I am saying is that for example ACR/LR not only might have exposure correction dependent twists in some camera profiles, but they might apply different hidden exposure corrections (not to mention again that process 2012 exposure correction is not linear in ACR/LR) based on the nominal ISO (different ISO = different corrections) for the same camera model... so any ETTR application shall take into consideration the tools that deal with raw file afterwards before you decide how you are going to expose - like the ISO it is not part of the exposure, but it is a part of your decision how to expose (before it starts) because it affects the processing when it (exposure) ends.

Before piling on to Adobe, one should recognize that there are ways to deal with the Adobe hue twists. Sandy McGuffog is the expert here and the referenced link discusses hue twists and how to remove them with his dcpTool. The DNG BaselineExposure offset that Adobe uses is not really hidden. It is in the EXIF of the DNG file and can be read with EXIF readers. Rawdigger can also read the offset. For my Nikon D800e, the BaselineExposure is +0.35 EV. One can get a good measure of the offset by exposing a uniform white or gray card according to the light meter and determine the raw saturation. This offset does complicate the evaluation of the status of the raw channels with the ACR histogram, but RawDigger is the proper tool for that purpose. FastRawViewer also works well for this.

Highlight recovery with PV2012 is nonlinear--it does roll off the highlights, but this is usually what you want with clipped highlights. If you need more linearity, you can fall back to PV2010.

Bill

[rogoldboy]

Jack: "The effects of the two approaches on IQ (ISO in-camera vs push in post) are shown here for a well designed (nearly) ISOless camera."

thanks for that link, it is making for interesting reading.

[Ray]

So with an ISOless camera you should attempt to ETTR at base ISO.

Jack

Now I'm getting a bit confused, Jack.  

Surely with all cameras, whether they are ISO invariant or not, one should attempt to apply ETTR at base ISO for best results, if the required shutter speed and aperture allow it.

Likewise, with all cameras, whether they are ISO invariant or not, one needs to apply the ETTR process regardless of  the ISO setting chosen, in order to get the best results, the best results being the lowest noise in shadows and mid-tones, without blowing wanted highlights.

For example, if I'm using a D7000 or D7200, which I would say are pretty close to being ISO invariant cameras, and I decide to use ISO 800, not only because I need a fast shutter speed, or because the light is not good, but also because I want to clearly see what I've shot on the camera's LCD screen, and/or share the images with others in the field, then I still need to apply the ETTR process at ISO 800 in order to achieve the lowest noise and the best review image.

In other words, any exposure which does not push the histogram to the right, whatever the chosen ISO, will result in more image noise.
Where's the confusion? The fact that one might not need to use a high ISO with an ISOless camera, if one doesn't feel the need to be able to clearly view the shots taken on the camera's LCD screen, does not mean that the ETTR principle does not apply if one does choose to raise ISO, rather than underexpose at base ISO.

However, that is not to deny that the ISOless camera has clear advantages. But that is a separate issue.

[mouse]

Before piling on to Adobe, one should recognize that there are ways to deal with the Adobe hue twists. Sandy McGuffog is the expert here and the referenced link discusses hue twists and how to remove them with his dcpTool. The DNG BaselineExposure offset that Adobe uses is not really hidden. It is in the EXIF of the DNG file and can be read with EXIF readers. Rawdigger can also read the offset. For my Nikon D800e, the BaselineExposure is +0.35 EV. One can get a good measure of the offset by exposing a uniform white or gray card according to the light meter and determine the raw saturation. This offset does complicate the evaluation of the status of the raw channels with the ACR histogram, but RawDigger is the proper tool for that purpose. FastRawViewer also works well for this.

Bill

Hi Bill,

Indeed, the hue twists are easy to avoid.  In fact most profiles (dcp) that one creates with the dng profile editor are "untwisted".  See my remarks on this site.

Interested in your comments about Baseline Exposure Offset being visible in the exif data of the dng file.  When I look, I too see a value of +0.35 for my D800.  However I am a bit curious about how that value got there and how it is used by the raw converters.  When I look at a NEF file (same image) that value is not found in the exif.  Or, at least I cannot find it.

[AlterEgo]

Before piling on to Adobe

nobody does - however it is worth reminding what it is... because people tend to talk about what ETTR brings to raw data, but forget that raw data will be dealt with with a raw converter and there you have its own share of nuances....

The DNG BaselineExposure offset that Adobe uses is not really hidden. It is in the EXIF of the DNG file and can be read with EXIF readers.

yes, but that means you need 1) convert to DNG 2) know to check for it

If you need more linearity, you can fall back to PV2010.

and then you might end up w/o other useful features that PV2012 brings

---

again this was not against ACR/LR but to remind the OP that his "then push it 5 stops in Camera RAW" must be with fine print attached