Author Topic: Let's talk lighting  (Read 1341 times)

thebishop

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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.


Martin

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Re: Let's talk lighting
« Reply #2 on: September 15, 2017, 08:52:19 AM »
Hi Bishop,

it all comes down to personal preference regarding tint/kelvin range/CRI but one aspect is very important to keep in mind/verify: no PWM driven light sources in or even near your setup.

You'll want very constant current and voltage driven (driver = controller) LED lights, else you'll notice pulsating brightness changes throughout your video.

I will tripod-mount several high CRI, (very) high output flashlights from my night-(geo)caching collection and see if that'll be enough ;)

For example this (amazing) person tests these lights thoroughly, including tests for any traces of PWM (Pulse Width Modulation): http://flashlightreviews.ca/reviews.htm
Not sure if this is a subject in every studio lights review?

All the best
Martin
« Last Edit: September 15, 2017, 09:07:51 AM by Martin »

thebishop

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Re: Let's talk lighting
« Reply #3 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.

tesla500

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Re: Let's talk lighting
« Reply #4 on: September 15, 2017, 02:00:15 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
« Last Edit: September 15, 2017, 02:04:10 PM by tesla500 »

jasonfish

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Re: Let's talk lighting
« Reply #5 on: September 15, 2017, 04:29:16 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.

They have a wall wart on their site, but it's not yet available for sale. In the meantime they suggest a 6s hobby LiPo, but that means buying another charger, not to mention the need to recharge every hour.

I'm seriously considering that Godox.

thebishop

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Re: Let's talk lighting
« Reply #6 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.

thebishop

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Re: Let's talk lighting
« Reply #7 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... :-)

sam

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Re: Let's talk lighting
« Reply #8 on: September 16, 2017, 06:10:41 AM »
Inspired by tesla500, I rigged up lights with the Chanzon 100W led modules ( here now, but this link moves around...).

I drive each of them with one of these constant current boost converters each.  This is probably overkill, but these are so cheap...  I mount the LEDs to the front of a cpu water cooling block, and the drivers to the back.  Right now I'm driving 3x100W LEDs, a water pump, and fan for the radiator with a 500W ATX power supply. 

Overall, this is ~25k lumens for ~$100.  It stays plenty cool, and works well, but I think there's lots of room for improvement.  And of course, now that my camera has arrived, it doesn't seem bright enough any more!

wilheldp

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Re: Let's talk lighting
« Reply #9 on: September 16, 2017, 01:34:02 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... :-)

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

thebishop

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Re: Let's talk lighting
« Reply #10 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.

thebishop

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Re: Let's talk lighting
« Reply #11 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!

jasonfish

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Re: Let's talk lighting
« Reply #12 on: September 16, 2017, 10:09:06 PM »
...or you will fry all driver boards...

Did that on my first one. :)

thebishop

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Re: Let's talk lighting
« Reply #13 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... :-)

Electra

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Re: Let's talk lighting
« Reply #14 on: September 18, 2017, 12:30:13 AM »
At least for smaller areas, a friend borrowed my camera and their lights were two or three 25 and 40W  LED 'spot lights'.. The kind with a grid of 3W LEDs each with their own lens. They are fairly cheap, waterproof(Not always a worry) and because they have a narrow beam, you can get a lot of light on a subject, at least up to about 8-9k fps and from a distance of about half 30cm to half a meter.
And at least at half a meter, the 40W 30 degree 'spot' outperforms my 100W  120 degree LED flood.

Huge powerful LED floods are great if you have large subjects or large splatter areas(Upside down mowers in your garage are a good example.:) but if your subject is fairly small, you can get away with a lot less light if you have good focus.  Or you can take a lot of light and make it much brighter... :)