For some modules this option “compensate for exposure correction” is activated by default and also recommended. Why is this so? After all, exposure correction is done deliberately for a reason. I mostly shoot in AV mode, using exposure correction all the time. So this topic is of some interest for people like me.
I’m curious to find out!
Best wishes from Germany
Daniel Spenner
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Your camera exposure automatically attempts to make the image mid-grey on average (depending on your metering mode it might apply that mid-grey to part of the image). If you use in-camera exposure compensation it’s usually to protect highlights (expose to-the-right), but we still expect that the camera’s calculation of mid-grey was probably reasonably accurate.
In the scene-referred workflow we essentially use the exposure module to define that mid-grey value for the remainder of the pipe. The tick box in the exposure module takes the image back to what your camera thought was mid-grey, because at this point in the pipe we don’t care about protecting the highlights (those are managed in the filmic module later on).
Obviously if you use metering and compensation in non-standard ways this might not suit your workflow so you can create your own exposure presets to match how you work.
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I understand why it is set up this way and in general I agree with your sentiment about the create a dedicated preset remark (i have created them), but…
This could be made smarter. Instead of blindly turning it on and applying a found compensation it should look for some other factors before doing so. I know of two:
- When shooting in Manual mode.
Exposure compensation doesn’t actually change any of the ISO, aperture or speed settings in this mode. You can, however, use exposure compensation to influence what the lighting meter shows. Without going into details I use this in certain cases. But even if the exposure compensation is set mistakenly/without knowing it it should not trigger anything in the exposure module.
This one should be rather easy to implement: M, A, S and P modes are standardized in the metadata (Exif.Photo.ExposureMode). - When bracketing.
Don’t think I need to explain why.
Although there are fields that show that an image is part of a bracketed series, this one might be a bit harder to implement. These Exposure Bracket Value, ShootingMode and BracketSettings fields (used by Nikon and Panasonic) don’t seem to be very standardized and darktable might not see the difference in some cases. For example: bracketing using my Nikon D750 does not trigger this in the exposure module, but it does when bracketing with my Panasonic LX100M2.
There’s also the possibility that an actual exposure compensation is in place which might (not?) be taken into consideration.
Anyway, just wanted to put this out there.
What cameras can you do that on?
Well, the metering in camera is limited to pretty much average lighting conditions to get mid-gray set properly. If you take an image of a high key scenery, you need to “overexpose” by 1 or even 2 stops. The same is true for low light scenes and “underexposing”. Otherwise your images will turn out wrong (too dark or too bright, respectively).
I would not consider this a non-standard way of using exposure compensation, because that is what it is meant for.
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If your intention is to make a high-key image then the final edit won’t be mid-grey on average so you will need to override what the exposure module does by default. I think the defaults assume you are doing ETTR and you still want an average mid-grey edit. It’s really the only (or most reasonable) assumption we can make.
Okay, then it´s fine to untick that checkbox in this case. That was the background of my question.
Thanks a lot!
Both my Nikon D750 and Nikon Z 6ii. This, influencing the lighting meter using ec in M mode, does not work on the Panasonic LX100M2 I have.
@elstoc : Just remembered, Tim posted a RAW a while back shot with a Nikon D3300. M mode and +3.3 ec. RAW to be found in this topic. Not sure if this feature is Nikon specific…
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DT does the same when compensating using spot metering right? Or am I mistaken?
Regardless it is a pretty bold assumption that the camera can guess the correct exposure for your intent. I dont think many photographers share that experience.
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darktable just checks for exposure compensation. It doesn’t check metering method or anything. It will never guess intent, it’s intended to be a default that captures what we think is the most common use case. The alternative would be to default at 0 which would be wrong for another set of users.
There’s no point trying to be too clever. Create your own preset if you want different behaviour.
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I think its unlikely to be the most common way of using metering and exposure compensation. Its fine though people can learn new ways. After writing 100 posts on pixls 
I do wonder though how anyone who has used a camera can think matrix metering gets it right except occasionally. Or that all the exp comp from the meter is ettr adjustment. Even when exp comp ettring only half or perhaps twice the compensation will be ettr the rest correcting exposure.
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I think, what Chris means, is that the camera meter is producing a mid-grey image. And the DT module assumes that it is presented a mid-grey image. All the looks and lighting adjustments can be done later on. Therefore exposure-compensation is corrected for, without assuming, this is the look you intend to produce. Of course, that’s only my understanding of what is happening. He seems to have a much deeper understanding of the physics and color science than I do.
I like that it comes across that way but I’m mostly (slightly educatedly) guessing based on what others have said.
Then don’t tell anyone! Haha!
It does, at least on some camera models (M mode with auto ISO).
If the ISO is only automatic, it is not M mode, it is TAV mode.
“TAV” mode is a term only used on Pentax cameras. For most other manufacturers, you select “M” mode on the dial to fix the aperture and shutter speed. The ISO setting is separate, and can be “auto” (in which case it will be set according to the metering in the camera” or it can be set to a fixed value.
If you are in “M” mode and choose a fixed ISO, then setting the exposure compensation dial to anything other than 0 is meaningless, and so the whole discussion of exposure compensation setting in darktable exposure module becomes moot.
Unless it also sets an expsoure compensation value in the Exif, in which case it will affect the exposure module and apply a “meaningless” correction.
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I think the simple reality is that the darktable devs are microwave-only chefs, and don’t believe that people can use lighting (of which the exposure compensation is a part) creatively.
The solution is to create presets for the Filmic and Exposure modules with their default settings, enable them for all photos and set “auto apply pixel defaults” to “none”. This gets you the Filmic starting point without the assumption that the camera’s meter is 100% correct all the time.
Or that we try to bake defaults for “microwave-only” photographers in the knowledge that true chefs will create their own.
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