Author Topic: Let's talk lighting  (Read 701 times)

John DeLonghi

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Re: Let's talk lighting
« Reply #15 on: September 18, 2017, 06:16:35 AM »
I've got 6 of these for close-ups:

https://www.amazon.co.uk/gp/product/B01GFWWSWE/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

and 3 x 24V 5 amp power supplies.

I don't think they'll give enough light for a large outdoor area with very high frame rate. I'm interested to see how those Godox lights work out.
What we need is an affordable 1-2kW LED or HMI light. Might investigate the cheaper end of the market i.e. China

thebishop

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Re: Let's talk lighting
« Reply #16 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... :-)

John DeLonghi

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Re: Let's talk lighting
« Reply #17 on: September 18, 2017, 07:05:31 AM »
I've had a look at the Godox range and ordered one of their LED1000 panels. If it really puts out the equivalent of 1kW, it's good value.

Might need to supplement it with a spot or two though. There are some second hand Arri 650s on Ebay around 150 which might fit the bill, but I'd much rather use LED if possible.

If the Godox 200 gives good results I might get one of those, but >500W output would be better.

jasonfish

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Re: Let's talk lighting
« Reply #18 on: September 18, 2017, 09:49:52 AM »
Wonder how these would work out. Sure, they're floodlights, but anything's a spotlight if placed close enough to the subject. :)

https://www.amazon.com/Morsen-50000LM-Outdoor-Lighting-Daylight/dp/B01MDUTTTQ
https://www.amazon.com/Super-Bright-Floodlight-Waterproof-Spotlights/dp/B01IOW3E5S

They are pretty huge though.

Camoit

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Re: Let's talk lighting
« Reply #19 on: September 18, 2017, 01:04:13 PM »
I'm going to do some testing With Dave Bunge. He owns a grip service company.
So in time I should have an idea of what lights to use that you won't see the 60 cycle flash effect. 
That is super annoying.
The guy has been in the film lighting business for 30 years so he is one of the go to guys when it comes to lighting.

http://www.sacramentogrip.com/

John DeLonghi

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Re: Let's talk lighting
« Reply #20 on: September 19, 2017, 05:05:40 AM »
Wonder how these would work out. Sure, they're floodlights, but anything's a spotlight if placed close enough to the subject. :)

https://www.amazon.com/Morsen-50000LM-Outdoor-Lighting-Daylight/dp/B01MDUTTTQ
https://www.amazon.com/Super-Bright-Floodlight-Waterproof-Spotlights/dp/B01IOW3E5S

They are pretty huge though.

I think you'll get flicker with a lot of those LED floodlights. I have a few different types and they all flicker.

My Godox 1000 arrives tomorrow. I've set up an objective comparison between the lights I have for the Chronos. If all of us could post frame grabs using our lights and the same settings I've used, we could get a better idea of how they compare in use. I've done some already with the LED spots I have.

Here's a (reduced) frame grab using the 1280 x 1024 setting of the scene:



I'm using the Computar 12.5-75 lens with the camera 1.5m from the subject and the lights 1.0m from the subject. I thought a greyscale/colour test card and matt black object such as a lens would make a good subject as most people with cameras of some sort are likely to have these. 

I'm going to take multiple test recordings with various levels of lighting and put all the resulting frame grabs onto one page so it's easy to see what lighting is required at different camera settings. The settings I'm using for each lighting level is:

1: 1280x1024, 1057fps, 476.1us
2: 640x360, 5904fps, 85.21us
3: 640 x 96, 21650fps, 23.14us

0db gain, aperture set just below zebra level or wide open if there's not enough light to require stopping down. WB and  BL set.

« Last Edit: September 19, 2017, 11:24:15 AM by John DeLonghi »

jasonfish

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Re: Let's talk lighting
« Reply #21 on: September 19, 2017, 08:01:47 PM »
Took my two Stratus LEDs, removed their controller boards and replaced them with a couple boost converters:

https://www.amazon.com/gp/product/B019SYX7BM

Because, ya know, what's the worst that can happen? ;)

With the Stratus boards:
Requires 24-28v @ 6-7A+ (for what??)
The lamp gets fed 27v
The fan gets 6v

With the new boards:
Requires 12v @ 2A (much easier to find)
The lamp still gets 27v, pulls 0.8-1A
The fan gets 12v (runs faster, lamp stays cooler)

With two of these lights placed 1m from the subject, I set the Chronos frame rate to 8,000fps, the shutter to 50%, and still had to stop the f1.8 lens down about halfway.

More trials to come, but after running for 30 mins, the heatsinks are cool to the touch, no flicker, and no change in amp draw.

John DeLonghi

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Re: Let's talk lighting
« Reply #22 on: September 21, 2017, 07:03:09 AM »
That sounds pretty good. I've done some tests and even with a Godox 1000 Panel and 6 x 48W LED spots, I'm only at f4.
Here are my results:



Conclusion: Need more lights!
« Last Edit: September 21, 2017, 07:18:35 AM by John DeLonghi »

thebishop

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Re: Let's talk lighting
« Reply #23 on: September 21, 2017, 12:27:56 PM »
It is kind of funny, I looked around and retrieved my old light meter (Minolta Auto Meter V F) - can actually be useful again :-)

John DeLonghi

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Re: Let's talk lighting
« Reply #24 on: September 27, 2017, 06:23:58 AM »
Took my two Stratus LEDs, removed their controller boards and replaced them with a couple boost converters:

https://www.amazon.com/gp/product/B019SYX7BM

Because, ya know, what's the worst that can happen? ;)

With the Stratus boards:
Requires 24-28v @ 6-7A+ (for what??)
The lamp gets fed 27v
The fan gets 6v

With the new boards:
Requires 12v @ 2A (much easier to find)
The lamp still gets 27v, pulls 0.8-1A
The fan gets 12v (runs faster, lamp stays cooler)

With two of these lights placed 1m from the subject, I set the Chronos frame rate to 8,000fps, the shutter to 50%, and still had to stop the f1.8 lens down about halfway.

More trials to come, but after running for 30 mins, the heatsinks are cool to the touch, no flicker, and no change in amp draw.

I've just ordered some of these Stratus lights. For the money, nothing else seems to come close to the output once you add the parabolic reflectors.
I can get 200W 24V power supplies so I think I'll use those rather then mess around replacing the controller boards, as it will still give me the option of running off 6S LIPO batteries if I need to in the future.

Interested in hearing whether you have any long term issues they way you've done it.

jasonfish

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Re: Let's talk lighting
« Reply #25 on: September 27, 2017, 10:31:19 AM »
I think you'll be happy, they really are fantastic lights.

And it should be stated that I don't not like their boards. I blew out one board when dinking around one night, so emailed the maker for troubleshooting help. We identified the bad component so I could try to find a replacement locally, and I ordered a second light direct from them. When it arrived, the tech had included a new component in the bag. Wonderful service!

Turns out that the first board ultimately had more problems than just that component (all my fault). So I had one working light, and one dead one.

The only reason I "replaced" their boards is that I already had a few of those converters in the lab and figured it was worth trying to revive the first light. After realizing that it worked just as well with far "simpler" input requirements, I swapped out the second working board as well.

So I have no bad feelings about their boards, and love the support I got. I just happened to go a different route that works better for me with the parts I have.

Stratus LEDs are amazing. Give them money. :)

John DeLonghi

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Re: Let's talk lighting
« Reply #26 on: September 27, 2017, 10:50:26 AM »


Stratus LEDs are amazing. Give them money. :)

I have! I've got 4 coming and 4 x 24V 200W PSUs. That should be enough light to get me going I hope!

NoDak

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Re: Let's talk lighting
« Reply #27 on: September 27, 2017, 06:25:22 PM »
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!

Hmmmmmmmmm. I wonder if we still have that crapload of old Socket 478 heatsinks at work. :D I'm sure the boss would be okay with me getting rid of them.

Okay, so one heat-sink per module.

I use the drivers that you linked.

I found a US-ish seller of those modules on eBay. http://www.ebay.com/itm/100W-watts-High-Power-SMD-LED-Chip-Lamp-Beads-White-Red-Blue-Green-RGB-UV-Light-/122046201688?var=&hash=item1c6a853f58:m:mBExdbhCP8WUQFmi4PpsUQw

Should I go with White or Cool white? 6,000k-6,500k vs 10,000k-15,000k? Yea it's $20 more than the aliexpress one, buuuuuut I'll prefer to get a US reseller.

Power supply, hmmmm. We have a bunch of old 24 VAC CCTV power supplies. Things are moving to PoE IP cameras, so we probably won't ever use them. I think they are 8 amps at 24 volts. Would need to add a bridge rectifier for sure.

Would I need to add a capacitor for the ripple this would create or do I need to not be a cheap-ass and get a proper switching PSU?

24 volt would probably be better than 12v to reduce the amperage required in the wiring.

I could just use the car battery I have for starting my generator and only switch on all the LEDs when I am about to trigger the camera. :-\

Do those drivers output the same voltage regardless of input voltage? Or do I need to have it always powered by 12v or 24v? I am guessing it's one or the other.

80,000 Lumens and probably blowing breakers.  ;D Even better, since it will be one module per heat-sink means that I can aim and mount them individually

jasonfish

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Re: Let's talk lighting
« Reply #28 on: September 27, 2017, 07:02:38 PM »
The boards I bought from Amazon, similar to sam's, have a constant voltage dial and a peak current dial. So yes, constant output voltage regardless of input.

NoDak

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Re: Let's talk lighting
« Reply #29 on: September 27, 2017, 07:34:59 PM »
The boards I bought from Amazon, similar to sam's, have a constant voltage dial and a peak current dial. So yes, constant output voltage regardless of input.

Nice, good to have options.

I see that you solder the driver directly to the module. (Not a problem, I can solder.) How do you go about calibrating them? Do you calibrate the voltage before you connect anything, then connect it to the module with alligator clips, calibrate the amperage with a multi-meter, solder it all down, then Loc-tite the screws in place? Or is there another way?