Messages

16

General high-speed discussion / Re: Measuring Speed

« on: September 19, 2017, 05:56:53 AM »

Maybe you'd like http://www.measureittape.com or https://www.amazon.com/Beacon-Yellow-Measuring-2-Inch-10-Yard/dp/B00JBF6ASQ? (there are many similar ones on the same theme)

17

Software Dev / Re: Initial feedback

« on: September 19, 2017, 05:51:43 AM »

The one thing I think would be helpful to all user is an exposure histogram.

A BIG +1 for this!

Definitely another +1 !

18

Chronos User Discussion / Re: Let's talk lighting

« on: September 18, 2017, 06:41:38 AM »

I'll let you know how the Godox works out - I want to light up essentially the size of the upper body of an archer and be able to have a decent DOF (and minimum 4K fps, preferably more, but then I can probably do more close-up...) - we'll see how far the setup will work.

I'll post results when I've been able to get delivery of all the gear!

Agree that an affordable 1-2kW LED rig would be fantastic... :-)

19

Chronos User Discussion / Re: Let's talk lighting

« on: September 17, 2017, 02:19:33 AM »

I went with 3 x Godox (200) + fresnels, will let you know how it works if interested when received lighting + camera - now the wait begins... :-)

20

General high-speed discussion / Re: Which cheap Amazon LED's are recommended?

« on: September 17, 2017, 12:28:17 AM »

Thanks for the detail!

Could you possibly try measuring with the fresnel in the middle of the zoom range? According to https://www.youtube.com/watch?v=7JuitNXvtQI it actually provided brighter light in the middle of the range (!).

21

Chronos User Discussion / Re: Let's talk lighting

« on: September 16, 2017, 09:41:20 PM »

I bought that exact setup.  I haven't had a chance to use it with the camera yet (mine will hopefully ship next week), but I did some testing on the light and lens.  http://forum.krontech.ca/index.php?topic=5.msg364#msg364

Thanks! I missed that thread, very helpful, great with the quantified measurements. Hope for non-flickering! Looking forward to hearing about your experience when you get the camera!

22

Chronos User Discussion / Re: Let's talk lighting

« on: September 16, 2017, 09:36:05 PM »

I've been using one of the Stratus LEDs with a benchtop power supply. It's plenty bright, but a real hassle to power. My PS only supplies 5.1A, which is barely enough. The other option is a pre-made 24v 7A wall wart, but I'd probably have to order 5 or 6 of the things to find one that doesn't induce flicker.

The Stratus in 2 x 10-array configs would have been excellent, but having seen the video for putting it together ("don't do this, or you will fry all driver boards", "avoid this, or the thing will literally explode") and only having basic aptitude for electrical work, I'd avoid it :-) But thanks for the link, it could definitely have been one possibility.

23

Chronos User Discussion / Re: Let's talk lighting

« on: September 15, 2017, 11:18:19 PM »

So looking at the Godox with the NG-10X fresnel attachment - according to an Amazon reviewer that gave about 30,000lux @ 1m, so two of those and going black-white should make f/4@4kfps more or less in range (preferably three to get down from 360 shutter...). Will continue to loo a bit more... :-)

24

Chronos User Discussion / Re: Let's talk lighting

« on: September 15, 2017, 10:57:56 PM »

As a rough estimate, for a color camera, you'll need about 7 lux per fps at f/2 and 360 degree shutter.

So at 4000fps, you'd need about 4000fps * 7 = 28,000 lux. If you want to run f/4, you'll need 4x as much light, so 110,000 lux which is about noon day sunlight

I'm afraid you'll need far more light than those Manfrotto lights will provide, unless you're putting them right next to the subject. At 1m (3') distance you'd need 18 of those lights for f/2 4000fps

Thanks a lot for that estimate, much appreciated!

I will try to change my preorder to a monochrome version then to make it easier to light the scene, then I can stop caring about CRI too, perhaps there are some cheaper/brighter light sources if that is a non-issue, will need to google a bit...

I would like to run with less than 360 shutter too (I want to use the camera for archery shot analysis primarily, want to see the arrow clearly as it leaves the bow).

I can put the lights slightly less than 1m from the archer, but not closer (need some safety distance).

Perhaps it is ok with som gain as well, I haven't seen enough comparable footage with/without gain yet to know if it is ok.

25

Chronos User Discussion / Re: Let's talk lighting

« on: September 15, 2017, 11:21:40 AM »

I hope the Manfrotto is stable, they make a big deal of "non-flickering" everywhere...

1600 lux @ 1m is perhaps not enough though, but will start with that and see how far it takes me, the Godox one seemed quite reasonable too.

Unfortunately, the cheap "big light" is mostly unavailable for me for the next 6 months or so... The downside of living a bit too far up north.

Any other experiences would be interesting, I guess it should be possible to actually calculate the amount of light that would be needed for a given set of video parameters for a reasonable exposure, but too complex for me right now.

26

Chronos User Discussion / Let's talk lighting

« on: September 15, 2017, 03:06:30 AM »

I just put in a preorder for the camera and are now wondering what people are using for artificial lighting?

Of course there are many factors playing, but looking at around 4K fps with minimal gain settings to reduce image noise, with say f4 aperture, what have people used successfully?

I am going to try with the Manfrotto LYKOS Daylight (https://www.bhphotovideo.com/c/product/1204246-REG/manfrotto_mll1500_d_lykos_daylight_on_camera_led.html?c3api=2572%2C113041717267&gclid=EAIaIQobChMI6bzn7fem1gIVSIGyCh2YZQfIEAAYAyAAEgKWVvD_BwE)
and if anyone is interested I will share the experience, but would be very interested to learn about other people experience with lighting.

27

Chronos User Discussion / Re: Need a tutorial on shutter speed

« on: September 15, 2017, 03:00:58 AM »

The main screen displays the shutter speed in percent of fully open, so 2x or 180 degrees would be 50% shutter. 100% would be equivalent to 360 degrees. To convert degrees to percent, divide by 3.6

Would people prefer degrees over percent? An option for either?

I think percent is _much_ more intuitive for "normal" new users without background of using a degree-based system before. I watched the slo-mo guys video quoted and when he describes that the degree is the amount of cut-out from a rotating disc, it just seems anachronistic.

I'd rather have percentage (or the option to choose if really people want the degree-notation).