Author Topic: Chronos 2.1 color study  (Read 554 times)

mklinger

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Chronos 2.1 color study
« on: July 07, 2021, 10:42:38 AM »
I wanted to do a quick color analysis to see what was happening at the various primary resolutions of the Chronos 2.1.
All the tests shown here are all taken with the same lens, exact same lighting conditions and exact same frame rate and shutter.

I have included an image from my Canon 1DX2 DLSR @ ISO 500 and 1/2000 as a comparable "reference" shot.

Each DNG image was given a simple white balance in Photoshop with the white target, but no other adjustments were made.

It's interesting to note that not only is there some serious color changes at the lower resolutions, but we're losing overall sensor sensitivity as well.  Is this a bug in the firmware or just an unfortunate characteristic of the sensor?  I'm not sure, but it's most likely the latter.

I'm just presenting this info for folks to be aware of.  If you want the absolute best quality, stick to 1920 and 1472 horizontal resolutions.  Only drop to the lower resolutions if you absolutely need the speed and know what the trade-offs are with respect to color quality and sensitivity.

I hope this type of data is useful to others.  I am coming to the conclusion from all my testing that the 1472 horizontal resolution is the absolute sweet spot for this camera as you gain ~43% speed for only a ~26% drop in resolution and the color, noise, and sensitivity is very close to shooting at full resolution.
 

Nikon1

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Re: Chronos 2.1 color study
« Reply #1 on: July 07, 2021, 11:44:07 AM »
It's interesting to note that not only is there some serious color changes at the lower resolutions, but we're losing overall sensor sensitivity as well.  Is this a bug in the firmware or just an unfortunate characteristic of the sensor?  I'm not sure, but it's most likely the latter.
Noticed that as well.
 My non-Scientific Observations showed that Resolution does some Weird stuff to the Sensitivity, also that gain Settings are not equal to a linear increase in sensitivity.
 Furthermore Framerate also does some weird stuff to sensitivity. I feel like you tend to tickle more the Higher end of framerates, but for me its sometimes the Mid to lower end this camera offers. So i didnt look all too much into the High end, but for the Low end, there is some weird stuff happening, planing to do a new Topic on that at some point, namely exposure Slider at 60fps.
 .
 Now you didnt leave any info what Firmware version you did your test on, so i assume 0.6.0
 Now while Noise Output overally vastly improved with the New Firmware Version, Sensitivity took a noticeable hit at moderate Framerates (1k/full Res, didnt check lower res) and a somewhat bigger hit on lower resolutions.
 Tested 5.1 vs 5.1 Unstable vs 6.0 when 0.6.0 got released, and the 6.0 was just quite a bit darker. Dont remember clearly anymore but must have been somewhere between 1/3 and 2/3 of a stop darker overall or something on full Res./ 1kfps.
 5.1 Unstable is still the most sensitive (and ironically the most stable at stupid low framerates) from my tests, so i keep it on an µSD Card in my camera case to have it with the camera at all times just in case.
 So it has to be at least partially be Software.
 I dont remember to have any Resolution vs Sensitivity comparisons from what i remember, apart from noticing that Sensitivity on Small Resolutions on 6.0 is generally somewhat worse somehow (never did any actual tests to quantify that, just general feel).
« Last Edit: July 07, 2021, 11:46:24 AM by Nikon1 »

mklinger

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Re: Chronos 2.1 color study
« Reply #2 on: July 07, 2021, 01:12:15 PM »
Yes, I'm currently using 0.6.0.

I'm just speculating here, but I would guess that there is not one "best" firmware settings wrt sensor gains and configuration for all possible resolutions and speeds.  The current firmware has probably been optimized for 1920x1080, 1000 fps, and 0 dB gain (and it does look very good at that setting) and everything else just falls where it falls.

We'd need some of the Kron engineers to chime in here to know for sure. 

I'm not sure what tweaks are possible at the firmware level regarding the amplifier gains and exactly how the resolution windowing works.  The fact that we're losing probably ~2 stops of light sensitivity going from 1920x1080 to 832x1080 at the exact same framerate, shutter, and gain tells me something odd is happening. 

Hopefully they can run some controlled lighting tests like this in their lab to see if they can find a good solution.

Nikon1

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Re: Chronos 2.1 color study
« Reply #3 on: July 07, 2021, 01:50:08 PM »
The current firmware has probably been optimized for 1920x1080, 1000 fps, and 0 dB gain (and it does look very good at that setting) and everything else just falls where it falls.
Can confirm, but have to say even the gain settings up to 24dB where optimized quite a bit (still obviously not perfect, but vast improvement in my opinion).
 On the older Firmware Versions 0dB was a Yes, 6dB was a Maybe, everything else above was usually a No for me.
 On the 6.0 they managed to make up to 12dB very useable (would still prefer 0dB unless i HAD to use higher gain), and 18dB bearable.
  also 720p (HD 16:9) @2,1kfps also looks way better on mine than with older firmware.
 So i guess main focus of the Image-Quality Improvement where the High resolutions, which Filmmakers would mostly use, which would complain the Loudest about their Footage looking not perfect.