Hello,

when calculating the Luminance, do you actually take the black level of the RAW data into account?

No, the Raw data is not being analyzed at all. The lum an visual_lum are being calculated from the camera previews / visual previews. This makes a lot more sense: deflicker needs to be calculated after the Lightroom developments have been applied. That's why it bases on the visual lum.

Ok I understand.

The Adobe DNG converter seems to be the problem.
Many Canon cameras change their black level depending on the ISO.

When I load a DNG sequence, I always get a jump when the black level changes.
If I load the same CR3 sequence, the jump does not exist.

Then the DNG converter probably recalculates the preview images and makes this mistake.

That's possible. I can only repeat what I always say: don't convert your Raw files to DNG. Work on the original Raw file, it will be much faster and save you from additional difficulties.

But with Lightroom 6 and EOS R i have no other option right now.

You should update to the latest Lightroom Classic. Version 6 is outdated (it's from 2015!) doesn't support modern cameras and is slow as hell. Saving here means saving at the wrong place. Just my 2 cents.

Version 6 is outdated (it's from 2015!)

The last update 6.14 is from the end of 2017, so almost 2018. Except for one camera, my cameras are all older... no reason to update...

But independent of an update…

I was not aware that the preview image is also recalculated when converting CR3 to DNG. I guess the DNG converter uses the same algorithm as in Lightroom Classic. So why shouldn't this also happen in Lightroom Classic?

If Lightroom Classic does that too, then it would even be good if LRT would take the preview image from the DNG. Then LRT could even compensate for that.

The error isn't very big, it's not really relevant for normal photography. But you can already see that in the timelapse video.

I'll have to ask a colleague to export the CR3 from Lightroom Classic...

This post was last modified: 2022-06-16, 21:39 by c_joerg.

I have now let the CR3 be exported to JPG with ACR.
The JPG from ACR shows the same jump at black level change as the previews in the DNG.
The preview images in CR3 or exported JPG from Canon DPP do not show this.

So it seems to be an Adobe ACR problem. Adobe is probably not so clear with the black level change. Admittedly, the differences are not great, but you can see the jump in time lapse.

The black level change at different ISO affects all Canon mirrorless ones that I know.

I can only repeat what I always say: don't convert your Raw files to DNG. Work on the original Raw file, it will be much faster and save you from additional difficulties.

Not in this case…
So it seems advisable to use Canon's DNG's instead of the CR3. Then LRT uses the preview images from the DNG and compensates for this jump.
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Sorry, I find it very confusing to follow you.
Certainly Adobe's engine has some issues and sometimes introduces effects like Contrast Flicker, as I explained in my Expert Tips Tutorial #5: https://lrtimelapse.com/tutorial/expert
But this is what we have to deal with, regardless of if we are using original raw files or dng. The latest versions of ACR, DNG Converter and Lightroom Classic all use the same ACR develop engine.

LRTimelapse uses the DNG converter to create the visual previews, but this doesn't mean that you should convert the files to DNG.
Converting to DNG has some disadvantages, like slower performance (embedded XMP etc.) and it's an additional step - I don't recommend it although it wouldn't change the end results.

So stay with the original Raw files, learn about the limitations in the tools and use the latest version of the tools.
Those are my recommendations.

Certainly Adobe's engine has some issues and sometimes introduces effects like Contrast Flicker, as I explained in my Expert Tips Tutorial #5: https://lrtimelapse.com/tutorial/expert

I know the video. The difference with the black level: It is always there regardless of the settings.

The latest versions of ACR, DNG Converter and Lightroom Classic all use the same ACR develop engine.

That's exactly what I saw and described

The lum an visual_lum are being calculated from the camera previews / visual previews.

LRTimelapse uses the DNG converter to create the visual previews, but this doesn't mean that you should convert the files to DNG.

That confused me a bit but I think I got it now and then it makes sense.

I once loaded a CR2 sequence of an M100.
I see a straight line because the "Preview Lum" comes from the embedded preview images of the CR2. They come from Canon.

Then the “Visual Lum” are calculated. Now I see the black level jump. In this case a real RAW development takes place with the DNG converter. This calculation then also changes when I change settings. Is it correct that way?