Author Topic: Canon EOS R5 / R6  (Read 82330 times)

Levas

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Re: Canon EOS R5 / R6
« Reply #275 on: June 10, 2022, 07:44:37 PM »
Wanted to know some more how the camera(Canon R5) behaves under different modes and different iso settings.
Shot some dark frames in different photo and video modes and loaded the into raw digger to calculate dynamic range based on noise.

Made a spreadsheet in google drive with some more info about the Canon R5:
https://docs.google.com/spreadsheets/d/1D3lpiMQniUzPiaVqDzAs5Gmc2hR9mIjDXpDe5IBTP9E/edit?usp=sharing

What suprises me are the different black levels.
In photo mode in iso 100 and iso 200 it's about 512.
While in all other iso modes it becomes 2048 (which is normal for most Canon camera's with digic 5 with ML support).
In raw video mode black level is 1024, all iso's also iso 100 and 200.

The Canon 6d always has black level in the 2048 range, unless when shooting 12 bit or 10 bit raw, then it becomes 512 and 256)
Does this mean that the Canon R5 is using 13 bit a/d conversion for video modes ? (would explain the black level shift from 2048 to 1024)
And what is going on with iso 100 and 200 in photo mode, the only modes where black level is 512, can't be because 12 bit a/d conversion I guess, dynamic range is highest at iso 100  ???

Furthermore, it seems that iso 200 can be best avoid(dynamic range wise), if 100 is not enough, you can go directly to iso 400  :P
Also, after iso 3200, every more stop of iso is a direct stop loss in dynamic range, so there is probably not much reason to shoot higher then iso 3200, since digital exposure push in post should give similar results.

So anyone has any idea what's going on with the different black levels, especially the black level of 512 with iso 100 and 200 in photo mode?

Levas

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Re: Canon EOS R5 / R6
« Reply #276 on: June 10, 2022, 07:54:11 PM »
What is also interesting, when shooting raw video in the raw lite codec, which has a compression ratio of 6:1instead of normal raw which has 4:1 compression ratio.
The max white value of both green channels become about 10780, not 15359. (16383(max 14 bit value) - 1024(black level) = 15359)
Both the red and blue channels still have 15359 as maximum white level.
So the extra compression is achieved with using lower values for green channels, which according to the measurements done with dark frames doesn't impact dynamic range.
Weird enough, there seems to be a slight advance in dynamic range when shooting raw lite instead of normal raw  ???.
Although this probably comes with a penalty of less fine detail, since the green channels seems to contain more noise reduction done already in camera, or the standard noise reduction kicks in more because of the lower values.

Levas

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Re: Canon EOS R5 / R6
« Reply #277 on: June 10, 2022, 08:34:09 PM »
For those interested, some comparison of raw video against the 6d.
Was hard to do, not easy shooting the same scene and layering the footage and matching colors etc.  :P

8k raw of the R5 scaled to ultraHD matched to aspect ratio of the 3x1 mode of the 6d.
It starts with R5 footage and wipes to 6d footage (3x1 mode, 1832 x 1856 -> 5496 x 1856 resolution scaled to ultraHD)
The footage is very comparible, but R5 wins on detail, far more detail in the leaves.
And the R5 can shoot more usable aspect ratios of course  :P (R5 footage aspect ratio is matched to 6d 3x1 mode.).
https://drive.google.com/file/d/1c059wQoWCMJmlSClCrJ7aq2N7DgEv2r8/view?usp=sharing

Another comparison, here the 6d is used in crop mode 2880 x 1200.
The 6d footage is placed on the R5 footage which uses the whole frame.
So the frame somewhere in the middle is the 6d footage.
https://drive.google.com/file/d/1ktI5tKHdYd80gjpT6c5AdFYYRvTDsdVq/view?usp=sharing

c_joerg

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Re: Canon EOS R5 / R6
« Reply #278 on: June 11, 2022, 01:31:46 PM »
The Canon 6d always has black level in the 2048 range, unless when shooting 12 bit or 10 bit raw, then it becomes 512 and 256)
I don't have 6D anymore, but how could you shoot 10 bit RAW with it?

So anyone has any idea what's going on with the different black levels, especially the black level of 512 with iso 100 and 200 in photo mode?

We had some trouble with my G1x and the Black level. This is also issue for some P&S.
The M100 changes its black level from 512 to 2048 at around ISO320.

May be something interesting for you:
https://chdk.setepontos.com/index.php?topic=12165.30
https://chdk.setepontos.com/index.php?topic=7069.0

But is changing black level from 512 to 2048 losing of 2 Bit?
If I have a maximum exposed pixel with 16383 and I half the exposure, then theoretically the value goes 16383/2 = 8192.
What I see is on my G1x:

With black level 512  =>   ((16383 - 512) / 2 ) + 512 = 8848
With black level 2048  =>   ((16383 - 2048) / 2 ) + 2048 = 9216

The RAW values in 1EV steps with black level 512 can be seen here

https://chdk.setepontos.com/index.php?topic=12165.msg126374#msg126374

EOS R

70MM13

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Re: Canon EOS R5 / R6
« Reply #279 on: June 12, 2022, 05:22:59 PM »
That's a great comparison, thanks very much!
The darks were far better on the R5 also.  Nice and crisp detail on the trunk of the beech tree.  The 6D was just mud.

If you are so motivated, a comparison of a very dark scene would be much appreciated, with the shadows lifted several stops...

Levas

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Re: Canon EOS R5 / R6
« Reply #280 on: June 13, 2022, 02:03:42 PM »
@C_joerg
Interesting, so black level changes happen on more canon cameras.
Not sure if I understand the stuff discussed in the links you send.
So am I right that one theory is that the camera actually uses a lower iso then it actually reports ?
So in case of the Canon R5, which only has black levels of 512 in iso 100 and 200, you think it actually uses a lower iso/gain, like 25 or 12.5 ?
Iso/gain is the only thing they can use,  a faster shutter speed or smaller aperture would both be noticed by people I guess.

The 10 bit and 12 bit raw recording is possible on the 6d with raw video recording in magic lantern raw.
This was done by using a register that act as digital gain, it pushes the values recorded 2 or 4 stops lower.
Now I think about it, that makes sense that in this case the black level becomes lower in value.
Digital negative gain also lowers the noise signal, so this means lower black level  ???

What I also see discussed in the links you send, is that the image data is rescaled in the raw files in camera.
This is also the case with the R5, max white value is always at 16383 - black level.
This makes it difficult to see what is going on...

The whole iso magic is also happening with clog1, clog3, highlight tone priority etc.
Minimum iso that is possible in 8k raw:
No log -> iso 100
Highlight tone priority enabled -> iso 200
Log1  -> iso 400
Log3 -> iso 800

When actually using the above settings and iso, and load the files in raw digger, you can see in the noise level that it's all the same, it's all recorded in iso 100 :P



nikki

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Re: Canon EOS R5 / R6
« Reply #281 on: June 13, 2022, 04:03:11 PM »
i like the 6d footage better