Messages

61

Chronos User Discussion / Re: Newbie Questions

« on: February 24, 2021, 09:28:52 AM »

Hi Matt,  I can try and answer most of your questions.

1.  The 5mm spacer is to account for proper focusing, usually at infinity.  This will depend on the lens.  The best way is to just check with the specific lens you want to use and see if you can focus properly.

2.  I haven't used an Expo Disk for white balance, but I've definitely used a x-rite color checker which has a proper white balance chip.  I like to shoot Cinema DNG with my Chronos 2.1 and do proper color balance/correction in post.

3. The Chronos 2.1 has what is effectively a 2x crop sensor compared to 35mm full-frame.

4. Unfortunately there is no exposure Histogram.  Hopefully that is something that can be added to the software at some time in the future as it would be nice to have.

5. Shutter angle on the Chronos is no different than any normal video shooting.  Around 180 deg gives you a very natural look to video wrt motion blur, but it's not a hard rule.  I would generally try and stay away from 360 deg shutter, but if you are shooting at extremely high speeds, that might be the only option.  It will be a tradeoff for "look" compared to boosting the gain that degrades the quality.  It's best to experiment a bit.

6.  You shouldn't have to do a black calibration after changing the shutter angle.  You definitely need to with changing resolutions and frame rates, and wait until the camera is fully warmed up for best results.   Also, search for my post on optimal horizontal resolutions, there are really only 4 base horiz resolutions on the 2.1: 1920, 1472, 1152, and 832.  Everything else won't gain you anything wrt speed - only file size, and would be the same as cropping in post.

62

Chronos User Discussion / Re: Post Chronos 2.1 clips here!

« on: February 14, 2021, 07:37:28 AM »

Here is a clip showing a balsa bridge breaking at 3540 fps (1472x432).  The camera has the latest V0.6.0 software installed which is a big improvement from what I can tell so far.

This is more in line with how I'm going to use the Chronos with my new channel.  Being able to do failure analysis on devices like this will help a lot in the design and optimization process.

https://youtu.be/oRiQ7f4fXPw

The high speed part starts around 1:25, but I think it's also interesting to watch it fail in real-time to see just how fast it is.

63

Chronos User Discussion / Re: Improoving Cooling on the 2.1 Sensor /Experimental

« on: February 05, 2021, 04:29:00 AM »

Something that might be worth considering is to just use all the components of the camera and put them into a new, much larger, custom case.  If your use case is in-studio, perhaps having something large like the size of a cinema camera would be OK.  That might also open up the possibility of using high end air cooling with a second battery or power supply if needed.

You might want to make a custom case for your water cooling ideas as well just to give yourself more room to work.

64

Chronos User Discussion / Re: What Lights Do You Use?

« on: February 01, 2021, 03:29:21 PM »

I have a pair of Godox VL300 300W LEDs and Aputure Fresnel 2x attachments.  I also have a Nitecore TM28 6000 lm flashlight that I have experimented with as well.

Has anyone played with any of the super bright LED flashlights for high speed work?  Something like the 100,000 lm IMALENT MS18?  Its extreme output is brief (< 1 min), but that might enough for Chronos recording.

65

Chronos User Discussion / Re: Post Chronos 2.1 clips here!

« on: January 23, 2021, 11:55:45 AM »

Here is some macro high speed using a Dremel to sand a piece of balsa. 

https://youtu.be/3p4ezCmsDkM

Lens:  Sigma APO Macro 180mm f/2.8 @ F11
Resolution: 832x540
Frame Rate: 4823 fps
Shutter: 221 degrees (1/7856 sec)
Playback speed: 50%
  (402x slower than real-time)
Dremel @ 11575 RPM

It's very challenging to get enough light shooting F11 at 4823 fps 221 deg.  I had both VL300s and a 6000 lumen flashlight about 5" away.

66

Chronos User Discussion / Re: Post Chronos 2.1 clips here!

« on: January 17, 2021, 04:56:12 AM »

This is my first test of the Chronos 2.1 camera.  I destroy simple balsa towers at various resolutions to get a feel for the best quality/speed balance. 

https://youtu.be/wFJdB_NOfBQ

1920x1080 @ 1000 fps
1472x816 @ 1893 fps
1152x648 @ 2992 fps (take 1)
1152x648 @ 2992 fps (take 2)
832x456 @ 5692 fps
832x240 @ 10488 fps

I've been really impressed with the camera so far.  My biggest observation, aside from sticking to the 4 primary horizontal resolutions, is to stay at 0 dB gain if at all possible.  It was much better for me to underexpose a bit and pull up in post than to go to even 6 dB of gain.

All of these shots were at 0 dB gain and shot in Cinema DNG.  There is some post production enhancement in DaVinci Resolve, but nothing extreme.

I've got a picture of my setup at the beginning of the video that shows how I set up the other hardware used: Canon 70-200 F2.8 IS II lens @ F4 and two Godox VL300 300W LED lights with Aputure Fresnel 2X ends.

To use the Canon lens at anything but wide open, I used a Canon DLSR to electronically stop the lens down and pull it off the camera while still on.  While a bit of a hassle, it's not that big a deal and it works well.

67

Chronos User Discussion / Re: Chronos 2.1 resolution/speed table

« on: January 15, 2021, 04:15:03 PM »

Following on to my previous post, I've created a handy table that uses the ideal horizontal resolutions and is color-coded by aspect ratio.

The intent would be to choose a desired ratio for your shot, say 2.00 which is color coded yellow in the chart below.  The four highlighted resolution combinations would be the ideal choice to maximize performance.

Hopefully this is useful for some folks!

Marc

68

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.