Underwater lighting with 7d advice

W

whizzkid

Active member
Hi everyone,

I'll be filming an underwater ballet dance for a music vid I'm filming in 2 weeks. I don't have much experience in this area. My plan is to have two subjects underwater dancing ballet like. I'll have 1 HMI par 1200 underwater light and housing for the 7d. I'll shoot in 60fps conformed to 24p.

I guess my questions are how much stops of light will I lose under water regarding the HMI and the housing. My editor said to get the shot 75% close to the shot I want it to be so im planning to put dark blue in the bg. Was planning to put green screen but after what he said it made me think.

Here's a peg of what I'm trying to achieve.
http://www.youtube.com/watch?v=Xpe_jB7T5BI&feature=youtube_gdata

thanks all in advance!
 
whizzkid said:
Hi everyone,

I'll be filming an underwater ballet dance for a music vid I'm filming in 2 weeks. I don't have much experience in this area. My plan is to have two subjects underwater dancing ballet like. I'll have 1 HMI par 1200 underwater light and housing for the 7d. I'll shoot in 60fps conformed to 24p.

I guess my questions are how much stops of light will I lose under water regarding the HMI and the housing. My editor said to get the shot 75% close to the shot I want it to be so im planning to put dark blue in the bg. Was planning to put green screen but after what he said it made me think.

Here's a peg of what I'm trying to achieve.
http://www.youtube.com/watch?v=Xpe_jB7T5BI&feature=youtube_gdata

thanks all in advance!
Click to expand...

I don't think 1200 W will do what you want. Start thinking about 5K-10K. Furthermore, you may want to think about using 1/30 shutter speed, because even with a significant amount of light output, by the time it reaches the subject, you'll be in the low light conditions.

While I've not done this for movie film, the last shoot the Wife and I did for stills, took a bank of 5 2500 Ws strobes, with several lampheads in softboxes giving overall illumination, with one small flash as a hairlight, Fujifilm Press rated at 800, shutter at about 1/30 (mainly because of the hokey way we synchronized the flash and the Nikonos, using the Nikonos flash and light slaves on the strobe banks.), and wide open f-stop at f/3.5, and even then 'some postprocessing was required' to pull the images out.

The models varied in depth ranging to near surface to perhaps 6-8 feet.

Since the models where fully clothed in 'wedding dresses', several spotters were in the water with paddle boards and other floating safety devices to get the model up if she got into trouble. The Wife, who has a relative good lung capacity was able to stay down for 1-2 minutes without using tanks.

Safety issues abound when water and electricity mix. So, all powered devices where taken to a GFI'd plug, and the zone for the lighting equipment was a 'no wet' zone.

Oh, yeah, and before I forget... the 7D is not an underwater camera... so here's an Ikelite solution:

http://www.ikelite.com/web_two/can_7d.html

Oh, yeah, oh, yeah... there is a slight 'enhancement' to the focal length of the camera underwater due to the different optical characteristics for water/lens interface. So, your effective focal length is perhaps perhaps 50% 'longer'... so you may want to choose a even shorter lens that you might think to get a wider coverage... for 2 reasons, the mentioned optical difference, but things floating, you and your subjects, never seem to stay in the 'narrow' field of view that a longer lens might have... and needless to say, focusing distance will be totally uncontrollable, and so, you need as much depth of field that a lens can provide wide open... (The last time I tried a digital camera underwater the 'autofocus' was useless...)
 
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I don't think shooting in 1/30 shutter would be effective since I'm doing slowmotion... I'm planning to use a 25mm lens so technically it'll be 40mm in the 7D. I'm also planning to put a dark navy blue in the bg. Use 1 1200 hydro par for key and 1 for back light. Plus adding the sun to the equation i should get some natural soft fill since the water diffuses the light for me.

The production doesn't have a budget for that housing. Nor to rent it... I'm thinking of buying this opteka pouch that's good upto 20ft. But thank you for your advice. I'll just have to wait for the test shoot and see what images I'll capture.

I'll post the finished video here soon. Hope things go well.
 
A 1200 watt HMI par is about as powerful as a 5k tungsten lamp...

I'm sure with the 7d you'll have enough light to work with, but as far as the 1200 being enough to key with...I wish I knew. Definitely does depend on how big the pool is and how wide you'd like your shots to be. I would stray away from green screen though, as it just doesn't sound like you've got the budget to do it right.

Interested to see how it turns out though. Good luck and be sure to post back.
 
RyanT said:
A 1200 watt HMI par is about as powerful as a 5k tungsten lamp...

I'm sure with the 7d you'll have enough light to work with, but as far as the 1200 being enough to key with...I wish I knew. Definitely does depend on how big the pool is and how wide you'd like your shots to be. I would stray away from green screen though, as it just doesn't sound like you've got the budget to do it right.

Interested to see how it turns out though. Good luck and be sure to post back.
Click to expand...

On the light power what is need is the specs on how many footcandles are being 'delivered' at what distance from the light. Then one has to take attenuation/scatter of water in to effect.

A 'black' background is a good 'keying' method for underwater... In general reds are attenuated more rapidly underwater.

The problem with shooting in 'daylight' is that one can not sculpt the light as dramatically as one would perhaps like.
 
whizzkid said:
The production doesn't have a budget for that housing. Nor to rent it... I'm thinking of buying this opteka pouch that's good upto 20ft. But thank you for your advice. I'll just have to wait for the test shoot and see what images I'll capture.

I'll post the finished video here soon. Hope things go well.
Click to expand...

I bought a housing for the Fuji S2 and I bought 4 S2 cameras... I also have about 4 Nikonos cameras... with water and cameras... anything can happen.

I have seen someone use the bag type container...
 
j1clark@ucsd.edu said:
On the light power what is need is the specs on how many footcandles are being 'delivered' at what distance from the light. Then one has to take attenuation/scatter of water in to effect.

A 'black' background is a good 'keying' method for underwater... In general reds are attenuated more rapidly underwater.

The problem with shooting in 'daylight' is that one can not sculpt the light as dramatically as one would perhaps like.
Click to expand...

That's what I've been debating with myself with, I wont have total control on the fall of fill in my subject, but i can use my key to control my exposure. So, I guess when I start grading, I'm planning to expose for the key and make it very contrasty.
 
whizzkid said:
That's what I've been debating with myself with, I wont have total control on the fall of fill in my subject, but i can use my key to control my exposure. So, I guess when I start grading, I'm planning to expose for the key and make it very contrasty.
Click to expand...

Did I mention the clarity of water...

I have been presuming this would be in a pool. Unfortunately pools vary widely on 1) maintenance, 2) method of filtration, 3) maintenance...

The 'cleanest' pool the Wife and I have shot in was in Hawai`i and the person who was renting the pool from a school was performing physical therapy in it. So, he had adjusted the chlorine(*) levels to the absolute lowest levels for a legal public pool, then had at his own expense improved the filtration system way above the original.

The worst pool experience was in New Orleans, when the wife gave a seminar on shooting underwater in pools, and the people stated they had access to a pool (a 'good' pool has sufficient area that has a depth of 8-10 feet.).

Well we got there and the people who owned it didn't believe in 'chlorine' treating their pool... that was bad stuff... and to conpensate for that they didn't seem to be to inclined to get a better filter than paper... and not to maintained at that...

We 'demonstrated' by there was absolutely no way the results would ever be useful. There was so much murk and scatter that you could not realistically shoot further away than 2-3 feet...

But the people had paid for the show, so they got it...

*Chorline levels will impact on a couple of issues, but mainly for people in the pool, how long they can be in before eye irritation becomes excessive. Many pools that are open to the public put the levels up just because if some some kid pisses or shits in the pool, the chlorine will 'help' in preventing evil things from growing... But the levels are usually so high that for a project like underwater 'model/performance' shooting, and the duration required to get something, it will be an issue.
 
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As a note, I notice that you list 'Puerto Rico' as your 'place', if you are in PR, there is Mosquito Bay on the island of Vieques that has high bioluminescent plankton.
 
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