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Underwater Lighting

underwater hmi daylight

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#1 Matthew Greiner

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Posted 24 March 2015 - 02:17 PM

Hello there, 

 

I have a project coming up in a couple months that will involve shooting underwater (most likely in a pool). The aesthetic is rather straight forward in that I just want to create a moody top-lit sunny look and shoot from below the surface and the subject, but my approach will change based on how the sun moves over the water (if it does at all).

 

If the location is shaded for the majority of the day, I will bring in a couple of HMIs to simulate the sun and shoot down into the water, but if the sun is already doing this naturally, I will most likely just work with that and schedule accordingly.

 

My question is, in the event that the water is in a shaded area that needs to be lit for sunlight, how big of a unit will I need to get this effect at a decent stop (2.8+) while creating enough ambient bounce-back (can be quite contrasty). Will an Arri M18 suffice or do I need something bigger like a 4K? At the moment, we're talking about shooting Red Dragon, so we will likely rate it at 800 ISO.

 

The concept is pretty abstract, so I'm completely ok with a fair amount of fall off.

 

Thanks!


Edited by Matthew Greiner, 24 March 2015 - 02:18 PM.

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#2 John E Clark

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Posted 25 March 2015 - 12:33 PM

I've only shot stills, with strobes for lighting, and no attempt to emulate 'sunlight'.

 

Things to remember:

 

1) Light attenuates in water due to 'the water', as well as particulate in the water. Even in pools that appear to be 'crystal clear' to the casual observer, often have particulate that may affect shooting. So, depending on the depth, 1 f-stop compensation near the surface, 2 f-stops at about 6-10 feet.

 

2) lenses 'change' in Field of View, due to the difference of index of refraction on the 'water/air' boundary of the camera housing, so, one may need a 'wider' lens that what one would choose on land.

 

3) Shooting at night with artificial light allows for more control of the light for 'mood'. Day time shooting while advantageous for the amount of light the sun gives, even in 'shade', does not typically allow one to direct the light for 'mood/atmosphere'.

 

The 2 major problems with artificial light are:

 

1) never enough photons in the right place at the right time, without major effort.

 

2) SAFETY. While I have heard stories of people doing pool shoots, with strobes and having the strobes fall in the water... I would advise major safety considerations, ground fault circuitry that is tested and working, cabling dressing, etc. That never happened on shoots I participated in, and a good amount of the set up time was considering how to safely secure lighting so as to prevent any such accidents.

 

General pool safety:

Spotters in the pool with buoyancy devices for anyone in the pool who runs into trouble. Several CPR qualified persons, should disaster strike.


Edited by John E Clark, 25 March 2015 - 12:34 PM.

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#3 Edward Lawrence Conley III

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Posted 25 March 2015 - 02:34 PM

http://www.littelfus...l-products.aspx


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#4 Stuart Allman

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Posted 25 March 2015 - 11:04 PM

A long time ago I was working with a director that wanted to get some shots of dogs swimming and we found this company...

 

http://www.deepsea.com/products/lights

 

So if you need some waterproof lights you might want to consult with them.  They normally work with marine applications, but seemed interested in film work.  Now, how you power the lights exactly?...I'm not sure.  I wasn't the DP for that shoot.


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#5 Edward Lawrence Conley III

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Posted 26 March 2015 - 12:13 PM

http://hydroflex.com

 

This company does underwater lights (for reference.)


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#6 Tyler Purcell

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Posted 27 March 2015 - 01:37 AM

It really depends on the mood and what you're looking to see in the background. Most underwater lighting is done from direct over head in a grid system of multiple smaller lights hung over the subject. Then key lights underwater will fill in the faces. Due to the backscatter effect, the lights facing the subjects need to be off-center. It's actually not difficult to get this all dialed in. Hydroflex makes housings for a few light meters, I usually rent whatever they've got available. They also rent the camera housings and hydropar lights.

If you aren't currently scuba certified, I highly recommend doing that before attempting any underwater cinematography. Being able to control buoyancy on your own is critical to getting a good shot. It's hard to do this if you're using hookah OR simply holding your breath. Some of these hydroflex housings are huge and can be unwieldy to deal with in the water. So being very self sufficient with SCUBA first, will allow you to focus on the shooting and not bouncing off the ground or surfacing every 20 seconds. I also use UW communication systems when shooting. OTS (ocean technology systems) rents/sells them and they work great. I always run an assistant camera underwater on SCUBA, who doesn't surface and then someone who goes between the surface and underwater to deliver what we need. The in-between person takes orders from the above crew, who is listening into our conversations. The fewer people in the water, the better. I refuse to run more then 3 shooting crew members and ALL of them must be SCUBA certified to be on my crew. I generally go diving with them before shooting if I don't know who they are. There is also one safety diver required for each talent in the water, especially if they're not on SCUBA.

Anyway, it's not a big deal… it's just a logistical nightmare and depending on how much material you need, it can take 4x as long to shoot underwater then above water.

Ohh and all the info above about safety and field of view is accurate, but the moment you dump the camera in the water, you'll figure those things out. :)
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#7 Matthew Greiner

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Posted 27 March 2015 - 07:56 AM

It really depends on the mood and what you're looking to see in the background. Most underwater lighting is done from direct over head in a grid system of multiple smaller lights hung over the subject. Then key lights underwater will fill in the faces. Due to the backscatter effect, the lights facing the subjects need to be off-center. It's actually not difficult to get this all dialed in. Hydroflex makes housings for a few light meters, I usually rent whatever they've got available. They also rent the camera housings and hydropar lights.

If you aren't currently scuba certified, I highly recommend doing that before attempting any underwater cinematography. Being able to control buoyancy on your own is critical to getting a good shot. It's hard to do this if you're using hookah OR simply holding your breath. Some of these hydroflex housings are huge and can be unwieldy to deal with in the water. So being very self sufficient with SCUBA first, will allow you to focus on the shooting and not bouncing off the ground or surfacing every 20 seconds. I also use UW communication systems when shooting. OTS (ocean technology systems) rents/sells them and they work great. I always run an assistant camera underwater on SCUBA, who doesn't surface and then someone who goes between the surface and underwater to deliver what we need. The in-between person takes orders from the above crew, who is listening into our conversations. The fewer people in the water, the better. I refuse to run more then 3 shooting crew members and ALL of them must be SCUBA certified to be on my crew. I generally go diving with them before shooting if I don't know who they are. There is also one safety diver required for each talent in the water, especially if they're not on SCUBA.

Anyway, it's not a big deal… it's just a logistical nightmare and depending on how much material you need, it can take 4x as long to shoot underwater then above water.

Ohh and all the info above about safety and field of view is accurate, but the moment you dump the camera in the water, you'll figure those things out. :)

 

Thanks for the thorough response, Tyler. I'm hoping that I will be able to hire an underwater cam-op to come onboard who's experienced with it so that I can focus on communicating with the director once the lighting is all set. I don't really plan on using any lighting units physically underwater...rather I plan on doing what you've mentioned - lighting from above and banking on there being enough ambience from whatever daylight there is to provide enough fill. Thus, I don't think any key lights under the surface will be necessary. 

 

It seems that hydroflex is more LA-based so I'm not sure it will be an option in NY, but a similar company called Gates offers housing packages through Abelcine out here so that could be the route we take. I should mention that I've done one other underwater shoot before, but it was with a 5d in a waterproof soft-casing. I learned how hard it can be to get shots for long periods of time without experienced ops and actors.

 

However, I think most, if not all underwater shots will be at 120fps creating a little bit more ease in how long we will need to be rolling. I figure a few good seconds on each take should suffice, but that said, all of the safety concerns are valid. I mentioned to the director that the actor should be a strong swimmer as the previous one I'd worked with struggled with performance underwater.


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#8 Guy Holt

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Posted 27 March 2015 - 04:47 PM

 I think most, if not all underwater shots will be at 120fps ..... but that said, all of the safety concerns are valid. 

 

Given your frame rate and the light attenuation of the water that John mentioned, you will need some sizable fixtures to light from above. I would think a 4k HMI or larger would be needed. Whatever fixture you decide to use to light the pool be sure to use GFCIs on all the cables supplying your lights – whatever size they happen to be. GFCIs are a must when working around water in order to avoid someone taking a potentially lethal shock. If you decide to go with HMIs you will need  film style GFCIs, like Shock Blocks, that are specifically designed for motion picture lights. To prevent the nuisance tripping that electronic HMI ballasts can cause with standard GFCIs, film style GFCIs sense on an "Inverse Time Curve." And, to deal with the harmonics that non-PFC HMI ballasts draw (that will cause other GFCIs to trip), film style GFCIs include a harmonic filter. Attenuated by the filter, the harmonics generated by dirty loads such as non-PFC HMI ballasts, pose less of a problem.

 

If you want to learn more about ground fault protection in wet situations, I have made available online an IATSE training curriculum that I developed for Local 481. It covers ground fault protection for everything from battery boxes to Crawford Studio generators. You will find it at this web address.

 

Guy Holt, Gaffer

ScreenLight and Grip

Lighting Rental & Sales in Boston


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