Underwater high frame rate video

[Greg F]

I understand that each frame captured then results in a shorter exposure time as you capture more frames, I am curious if there is anybody who can lend me a hand in understanding what the implications of 120+fps are? What kind of lighting is required for this to work? Primary footage will be shot below 20m underwater and then further down to 30-40m anything beyond that will require artificial light I know.

Thanks Much!

 

[Rudi Herbert]

It can be done, but you will need light, plenty of it, and not just below 40 meters, but as shallow as 15 meters for sure. 120 fps is a common exposure in stills photography, so that in itself is not a problem, but unless you are in very shallow water (10 meters maximum) in clear water with lots of sun, or you are deeper but pointing the camera up towards the surface, in which circumstances you can shoot at 120 fps without too much trouble, you will need lights with you. I've shot on Epic at 96 fps in 100 ft/30 meters of water, in clear days at noon with high incidence of ambient light, and still needed two video lights with me. I would recommend having at least 10,000 to 15,000 lumen of light available, more if possible, and test your shoot with that. That amount of lumens divided in 2-3 heads if you're shooting reefs, only 1-2 if you're shooting macro, and depends if you're shooting people. Macro is always very easy to shoot at high speed since you're so close to the source, but anything else becomes a trial and error process. If you could tell what your subject is, then it would be easier to ascertain the situation.

 

[Greg F]

Well lets see subjects are highly unpredictable, I am shooting vary animals. Galapagos Sharks, Scalloped Hammerheads, Grey Reef Sharks, Whitetip Reef Sharks, Oceanic Blacktips, Tiger Sharks (rare), Whale Sharks are not of line, Nor are Whales! Its highly unpredictable what I will see Eagle Ray my buddy and I filmed for a good 20 mins solid yesterday! I shot it with my DSLR though so its not as great as what I would like. There is also fish everywhere that I will shoot video of among other subjects. The reality is I predominantly shoot wide very wide.. 10-18mm range usually

What housing/lens are you using too when shooting high framerate? I am sure it will be lots of experimentation and frustration as always is underwater but thanks for the feedback its very much appreciated.

I will note I get very close, close enough to track their eyeball following me and see the white around the eye! This was shot with my Canon with a 60mm Macro Lens

 

[Pawel Achtel]

Greg, welcome to Reduser.

I routinely shoot high frame rates underwater. Obviously, if you shoot 120 fps you would need five times as much light as you need when shooting at 24 fps. Here is an example of footage shot with DeepX at 120 fps shot by one of our customers: https://vimeo.com/48845333 It required 12kW plus two 6kW HMIs and the footage is well-exposed.

I typically shoot 48 fps and I use at least 26,000 lm (~1kW) for small subjects (less than 1m away) when shooting at f5.6 - f/8. Larger subjects and further away would require more light or wider aperture to expose properly.

Most underwater optics do not perform well at large apertures. We have recently tested Nikonos 15mm as well as a trditional dome port and terrestial lens combination and concluded that the Nikonos 15mm is the only wide angle underwater optics able to resolve 4k at f/2.8. Dome port and terrestial lens combination would typically resolve less than one a few hundred lines at that f-stop and results were very poor.

Hope it helps.

 

[Paul Ellington]

Greg, welcome to Reduser.

I routinely shoot high frame rates underwater. Obviously, if you shoot 120 fps you would need five times as much light as you need when shooting at 24 fps. Here is an example of footage shot with DeepX at 120 fps shot by one of our customers: https://vimeo.com/48845333 It required 12kW plus two 6kW HMIs and the footage is well-exposed.

I typically shoot 48 fps and I use at least 26,000 lm (~1kW) for small subjects (less than 1m away) when shooting at f5.6 - f/8. Larger subjects and further away would require more light or wider aperture to expose properly.

Most underwater optics do not perform well at large apertures. We have recently tested Nikonos 15mm as well as a trditional dome port and terrestial lens combination and concluded that the Nikonos 15mm is the only wide angle underwater optics able to resolve 4k at f/2.8. Dome port and terrestial lens combination would typically resolve less than one a few hundred lines at that f-stop and results were very poor.

Hope it helps.

Beautiful Pawel.

 

[Greg F]

Greg, welcome to Reduser.

I routinely shoot high frame rates underwater. Obviously, if you shoot 120 fps you would need five times as much light as you need when shooting at 24 fps. Here is an example of footage shot with DeepX at 120 fps shot by one of our customers: https://vimeo.com/48845333 It required 12kW plus two 6kW HMIs and the footage is well-exposed.

I typically shoot 48 fps and I use at least 26,000 lm (~1kW) for small subjects (less than 1m away) when shooting at f5.6 - f/8. Larger subjects and further away would require more light or wider aperture to expose properly.

Most underwater optics do not perform well at large apertures. We have recently tested Nikonos 15mm as well as a trditional dome port and terrestial lens combination and concluded that the Nikonos 15mm is the only wide angle underwater optics able to resolve 4k at f/2.8. Dome port and terrestial lens combination would typically resolve less than one a few hundred lines at that f-stop and results were very poor.

Hope it helps.

Understood, I will likely be limited in what I can do at high frame rates.. However its not impossible! Just very ANGERER inducing I am sure.

The lights I am looking at are Keldan they are 6000 lumen and getting two of them.. I cannot carry much more due to the conditions that can be possible at the dive site, namely current that will make everything I do even the more challenging. Would a 1.8 prime make a huge difference over the 2.8? I am sorry I do not exactly understand how the optics all work in this regard.

And thanks for the Welcome

 

[Johnny Friday]

Greg,
the subjects you are shooting are not very conducive to light being shed upon them and in most cases will run away from you....Galapagos is a good example of where all those animals you named congregate and i assume you are shooting there. Also, having light is one thing, but getting it on your subject and balanced is another. So many times say on a 15m whale shark you have a nice bright spot on the whale shark that does not look right within the entire scene...In many cases you need to make the call to go with lights or not to go with lights. Lights will be beautiful when traveling through a school of jacks and getting light bouncing, but try that with a school of hammerheads at Darwin's Arch and you give yourself away and the sharks run from you. So in what you laid out with those animals, i tend to think lights are not your friend and use them when the time calls and that is an experience thing when to know to use and when they are of no use.

 

[Pawel Achtel]

Understood, I will likely be limited in what I can do at high frame rates.. However its not impossible! Just very ANGERER inducing I am sure.

The lights I am looking at are Keldan they are 6000 lumen and getting two of them.. I cannot carry much more due to the conditions that can be possible at the dive site, namely current that will make everything I do even the more challenging. Would a 1.8 prime make a huge difference over the 2.8? I am sorry I do not exactly understand how the optics all work in this regard.

And thanks for the Welcome

I use Keldan as a fill light for small subjects. In my opinion, they are better than most compact lights on the market. But, lighting large shark when shooting 120 fps would be difficult unless you can get within a couple of feet.

Sorry I wasn't clear, when you shoot wide open through a dome port the image will be very soft, as soft as VHS tape! This is what happens with large sensor, relatively small dome and wide aperture combination. The effect is due to image field curvature and results in sharpness falling off dramatically from the centre. You would be better off using small sensor camera instead, like HDCAM. Flat port will be even worse and not suitable for wide angle cinematography.

Most u/w film makers that use dome ports with RED Epic started using fish eye lenses because they are not adversely affected by image plane curvature. But, fish eye lenses too perform poorly wide open even before submerged in the water.

The best solution that I found is to use water contact lenses: the fabulous Nikonos glass that doesn't require ports and was specially designed to take sharp pictures underwater. Unlike dome ports, these lenses produce flat and undistorted image that are sharp from corner to corner and out-resolve the Epic sensor. This is how DeepX was born - the only housing able to resolve 4k (and beyond) for underwater wide angle cinematography.

 

[Johnny Friday]

Here's a few shots of sharks with only ambient light....shot at a seamount in Baja and the Salmon shark in Alaska. The hammerheads shot with ambient light at around 40m--they are far more shy and stay away from lights and noise--especially open circuit bubbles. the Salmon shark shot using loads of light.....but none of these at 120fps....I'm not sure why the need to shoot these animals at 120fps....since they are very easy going swimmers and beautiful swimming at an easy pace. I could see doing topside predation or near surface at 120fps...but why would you shoot whale sharks and the above mentioned at such high speed? I'd say at MOST 48fps if some are moving fast....and/or you need to cut the light as at places like Tiger Beach in Bahamas.

[/url] Hammerheads on Seamount by RedCineUnderwater, on Flickr[/IMG]

[/url] SalmonShark by RedCineUnderwater, on Flickr[/IMG]

[/url] Hammerheads in Open Water by RedCineUnderwater, on Flickr[/IMG]

 

[Greg F]

Johnny,
Full well aware of the animals, I dive twice a week with them for extended runtimes I dive a Mark 15 mostly now over my Inspiration. The animals are less and less skittish around me and my buddy has lit them up with lights on the order of 2ft away from him. However I will note its the same animals quite frequently and they do get to know you if you spend this level of time with them. I have done 87 dives this year at that site so far. It might seem like I am just stating random stuff I am being guarded about what I do sorry I likely dive my rebreather more than most people in the world, I actually get concerned about hyperoxic myopia.

I full well understand though your concerns of the animals and I will let you know how it goes for sure. And the sharks know where I am when they come through and are fully aware of me watching me I can see their eyeballs move as I mentioned previous.

Here's a few shots of sharks with only ambient light....shot at a seamount in Baja and the Salmon shark in Alaska. The hammerheads shot with ambient light at around 40m--they are far more shy and stay away from lights and noise--especially open circuit bubbles. the Salmon shark shot using loads of light.....but none of these at 120fps....I'm not sure why the need to shoot these animals at 120fps....since they are very easy going swimmers and beautiful swimming at an easy pace. I could see doing topside predation or near surface at 120fps...but why would you shoot whale sharks and the above mentioned at such high speed? I'd say at MOST 48fps if some are moving fast....and/or you need to cut the light as at places like Tiger Beach in Bahamas.

How common are large numbers like this?

 

[Pawel Achtel]

...trying to light a shark with 1kW

 

[Greg F]

Pawel,
Not much ambient light there for sure! That is awesome looking no way in hell I could wield something like that in the current here LOL