Lighting question

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Lighting question

Postby agosnell » Jan 31, 2012 2:08 pm

There is a large fairly deep body of water about 30ft deep and about 60ft in diameter that I would like to light up, I have 8 slaves and a decent camera. Any suggestions on how to get the light to the bottom of the lake? It is in a cave in TN. The water is usually crystal clear with a slight green hue.
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Re: Lighting question

Postby rlboyce » Jan 31, 2012 6:42 pm

Don't they make transparent waterproof containers? Maybe place a couple of these in the water with flashes inside. Use enough weight to counter any buoyancy, and of course tether them so that they can be retrieved after shooting. I wonder how well the slaves would pick up a signal under water and through a box...
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Re: Lighting question

Postby Leclused » Feb 1, 2012 4:55 am

You can build in the flashes in a transparent pelicase. Or if you have a powerfull led light (sten, nora, scurion) then you can use the lamp underwater.

Here are 2 photos https://picasaweb.google.com/1020341718 ... 3704235458
https://picasaweb.google.com/1020341718 ... 8478227010
where the persons holds the pelicase downwards in a pool.


Br

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Re: Lighting question

Postby citracaver » Feb 1, 2012 1:45 pm

Multiple waterproof 50 watt HID's or 100 watt halogen's without a reflector and weighted to sink to the bottom will work miracles. In a pool that big anything smaller is just going to make you mad. Getting well lit water shots is not easy. Or cheap...
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Re: Lighting question

Postby LukeM » Feb 1, 2012 2:04 pm

citracaver wrote:Multiple waterproof 50 watt HID's or 100 watt halogen's without a reflector and weighted to sink to the bottom will work miracles. In a pool that big anything smaller is just going to make you mad. Getting well lit water shots is not easy. Or cheap...


What is the advantage of this over using flash units? Flashes are much cheaper considering they can be picked up for very little $ on Ebay and the only real cost is slave units.
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Re: Lighting question

Postby citracaver » Feb 1, 2012 2:43 pm

In just a few seconds of exposure they put out WAY (I'm talking orders of magnitude) more light than a bunch of flash units could. With a little creativity, you wont end up with a bunch of hot spots like you would with flashes either. If you really want to do the water shots you have to want it bad. Hauling the gear and setting it up without disturbing the bottom is a PITA. My friend and I have built a lot of custom lights for this purpose. It takes a lot of time and effort, but not necessarily more money than it would cost to buy all the flashes and slaves required to do it the "traditional" way (flash in a waterproof box in the water) which would be a lot! Flash really just isn't practical for a pool 30 feet deep and 60 feet wide.
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Re: Lighting question

Postby LukeM » Feb 1, 2012 3:50 pm

Good points, although I think doing something quite similar would be achievable with flashes, but probably would generate more hassle. By the way, there are some very bright electronic flashes available that allow the use of the bare bulb to get a non-focused source.

Doing some back of the envelope calculations it looks like a few seconds of exposure with a 4500 lumen flashlight would be less than an order of magnitude brighter than one firing of a flash. 2 seconds of exposure would be something like 4-8 times as bright as one flash from something like a Vivitar 285, so multiple firings could achieve the same result. I guess I'd say if you already have some flashes it's worth investigating that route before looking into sources of constant illumination.
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Re: Lighting question

Postby citracaver » Feb 1, 2012 4:20 pm

Don't get me wrong, I'm not saying you can't do it with flashes. I have fifteen electronic strobes and I would choose to use the HID's in the water instead of the strobes every time. I hardly use strobes for cave photography at all anymore. Most of the time I use LED and HID. You have a lot more exposure options with a constant source of light vs a flash. I guess I'm jaded, cause I have eight 50 watt HID's at my disposal... It would take a lot of flashes in the water to equal that.
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Re: Lighting question

Postby agosnell » Feb 4, 2012 2:27 am

I got to looking at the HID option, to do it right would cost over 800 it seems. That's pricey at the moment.

I found some waterproof transparent bags on the internet. I think I will try to put a rock in a couple of them with the slaves attached to a string.

Thank you for the idea's!
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Re: Lighting question

Postby polrbear » Feb 4, 2012 1:38 pm

I'm not sure how well the slave option would work without wiring. Most of the slave systems I have come across are infra-red based communications. I learned quite well in photochemistry classes how a few _centimeters_ of water will absorb almost all of the IR light that one tried to pass through it.

If you have a radio frequency transmitter, that can travel through water, but there is still less distance that can be achieved than one can do with wires or above ground/straight passage.

Best of luck!

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Re: Lighting question

Postby NZcaver » Feb 4, 2012 4:20 pm

For what it's worth, optical slave triggers designed for caving (Firefly, Gibson, etc) seem to do just fine triggering a fair distance underwater. Of course we're talking clear water with the trigger and flashgun encased in a clear waterproof container.
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Re: Lighting question

Postby agosnell » Feb 4, 2012 9:05 pm

I have 6 digislaves. I 500 dollar nikon flash on camera, 1 no name slave and 4, 7 dollar small slaves.
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Re: Lighting question

Postby citracaver » Feb 6, 2012 8:53 am

You can build underwater HID's out of PVC and car headlight kits you can get on ebay for less than $100. The most expensive part is the lithium battery and charger to run them. The only real specialized item you have to find is a test tube of appropriate diameter to put the bulb in. My buddy has made 5 of them and they work great. We use them for cave diving too. :big grin:
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Re: Lighting question

Postby agosnell » Feb 6, 2012 12:25 pm

:) cool. Can you convince your friend to post a picture and maybe some details?
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Re: Lighting question

Postby citracaver » Feb 7, 2012 10:15 am

He is not on this forum so I'll post a few of his pics here. He really is a pro at building lights with stuff from Lowes/Home Depot. Some of these lights have been to 300 feet deep! They were intended for cave diving only when he started building them, but newer models have been adapted to be able to run out of the water so they don't overheat and melt. They are awesome for video too.

Image



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