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Topics - mklinger

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Chronos User Discussion / 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.

Chronos User Discussion / Chronos 2.1 noise study
« on: July 03, 2021, 07:21:01 PM »
I spent a fair amount of time trying and understand the noise characteristics of my Chronos 2.1.  From previous work, I determined that there are really only 4 native horizontal resolutions that should be used from a speed perspective: 1920, 1472, 1152, and 832.  Anything else is the same as cropping in post.

I wanted to better understand the noise of each of those base resolutions as well as if vertical resolution had any effect.

Unfortunately, it does look like vertical resolution effects noise level and patterns, especially at the higher gain levels.

My process for all of these runs were as follows (all done via the web interface):

  1. All tests were done with the lens cap covered at all times and the camera had warmed up for 30+ min.
  2. Select the resolution, gain level, and max frame rate
  3. Do two black level calibrations in a row
  4. Save the 100th image as a DNG file
  5. Load the raw images into Photoshop
  6. Overlay the images, flatten the layers, and then boost the global image gain equally across all tests

I also ran a test to see if speed itself made a difference.  It looks like it does somewhat.

I'm not sure what my conclusions from all this testing are.  1920 and 1472 are definitely the best resolutions to use and keeping gain to 0 or 6 dB is ideal.  I was a bit disappointed at what a mess the 832 resolution was even at 0 dB.   The noise seems very inconsistent and all over the place.  I would use 1152, but only sparingly.

Let me know what you think!  This type of testing should be reproduceable fairly easily.  It might be interesting to see if different sensors behave differently. 

My camera is using version 0.6.0 of the software and reports FPGA Revision 3.24 and PMIC Firmware Version 11.

I can zip up all the DNG files I used if anyone is interested in looking at them directly.

Chronos User Discussion / Chronos 2.1 resolution/speed table
« on: January 15, 2021, 03:39:59 PM »
Hi everyone, I just took delivery of my Chronos 2.1 today and am excited to start making videos!

I wanted to better understand the relationship between the various resolutions and max frame rate.  As you probably know, as you window-down the resolution, you have access to faster speeds.  In general, the camera does 2.1 Gpix/sec, but in reality, I've found it can range from 2.28 Gpix/sec to 1.48 Gpix/sec. 

I knew that there was overhead wrt to frame generation and different horizontal resolutions, but what was somewhat a surprise to me is that the camera really only has 4 ideal horizontal resolutions: 1920, 1472, 1152, and 832.  Anything different than those, it'd be the same as cropping in post. 

For example, the absolute highest pixel rate for the camera is 1472x1080 @ 1434.28 fps.  If you shoot at 1184x1080 you can still only go 1434.28 fps, but when you make the tiny jump to 1152x1080 you make a big speed bump to 1808.06 fps.

It looks like there are no surprises with decreasing vertical resolution as the size correlates well to framerate in a smooth fashion.

Check out the attached image for the full chart.  The first one shows the resolution and max frame-rate and other one shows pixel rate color-coded from green to red from fastest to slowest.

I thought it was interesting and might help others focus on ideal resolutions to get the most from the camera.

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