Underwater

Varun Nayar · December 8, 2006

Hi,

i am going down to shoot underwater to cover some NGO's marine work. We are carrying a sony handycam 42E with its housing, a Sony Z1 with its housing and a Sony D30 Beta. Now i swim well but have never dived before. I urgently need to know about the procedures for an underwater shoot. The shoot majority will be in the lagoons bordering the sea (depth of 15-20 feet) where reefs are much clearer. Is it going to be hard to stabilise the camera. Last time we shot shallow reefs with the handycam, it created fogging in the lens after fifteen minutes. (depth of 6-7 feet). Any underwater specialists out here. Please help....(Doug Allan ???)

Bob Hayes · December 8, 2006

First 15? to 20? is the area for SCUBA diver or very experience free divers. It takes time to get down and set up your shot and unless you can hold your breath for two minutes forget it. SCUBA diving with out proper instruction is suicidal. So take a class if you plan to dive.

But with regards to your fogging problem. It is very important that the camera and the inside of the housing are completely dry. That means no wet hands or water dripping inside. Story the camera with some rechargeable silica gel will help. There is a kind that recharges by putting it in an oven. But in the tropics you must use it immediately.

Patrick Cooper · December 8, 2006

To reduce the chance of fogging of the glass of the housing's port or lens (which is caused by condensation - bringing a warm object like a housing from the surface into the cold water below) tape a pack of silica gel to the inside of the housing. This will absorb moisture. Make sure though that the silica gel is yellow (warmed and dry) and not in the stage of turning orange or pink.

I see that you have done some underwater filming before so are you familiar with concepts such as refraction, colour absorption, back scatter etc?

If you have never dived before, i recommend doing a course first and becoming a competent scuba diver before doing any underwater photography while scuba diving.

Varun Nayar · December 8, 2006

SCUBA diving with out proper instruction is suicidal. So take a class if you plan to dive.

:D

Hi bob,

thanks. These NGO's have something on giant clamps and they are experienced divers. I will be taking a two day open water (dont really know) course before diving. But really, thank you for the advice on the fogging. The sony sport underwater housing for handycams came with a small bottle with some japanese written on it. they said it is used as an anti fogger but did not help. or we dont know how to use this liquid. Anyone know what this could be.....?

thanks

Varun Nayar · December 8, 2006

"I see that you have done some underwater filming before so are you familiar with concepts such as refraction, colour absorption, back scatter etc?......"

:blink:

no. I have dived in shallow waters with a handycam not in deep waters. We are planning to shoot HDV with the Sony Z1 P. This is only my 7th major work (and 3nd year) as a budding wildlife cameraman, and first for a underwater documentary. So I am still learning.

Please educate me...

Patrick Cooper · December 8, 2006

Okay then...let me explain...

First thing's first....you probably already know this but...when filming underwater, it is necessary to get physically close to your subject. The less water between you and your subject, the more sharper and clearly defined your subject will be. The greater the distance, the softer and hazier your subject will appear. Not surprisingly, the clearest images with the greatest amount of visible detail underwater will be obtained during macro photography. When filming in exceptionally cloudy water, macro photography may be the only means of getting acceptable images on film or video.

A wide angle lens is preferable in underwater photography and there are several reasons for this. Firstly, short focal length lenses have increased depth of field. With adequate depth of field, all that is necessary is a rough estimation of your subject?s distance and a rotation of the lens? focusing scale to this same distance should render the subject in sharp focus. Additionally, a wide angle lens will make subjects appear further away, forcing you to move closer to fill the frame, thereby improving picture clarity and sharpness.

Now a bit about refraction......a wide angle lens will benefit significantly if your underwater housing has a dome port as opposed to a flat viewing port. With a dome port, the lens retains roughly the same angle of view underwater as it does on the surface. You may have noticed while snorkeling or scuba diving that objects appear closer and larger through your face mask than they do above the surface. Likewise, when you place your hand in an aquarium filled with water, you?ll notice that your hand appears slightly larger in size when viewing from the outside. This phenomenon is known as refraction and occurs when rays of light passing through water enter a less optically dense medium like air and are subsequently bent and redirected from their normal course of travel. Basically, this results in a narrower angle of view when a lens is placed behind a flat port as well as some distortion at the edges of the image when a wide angle lens is used.

No refraction occurs with a dome port. This is because all light rays intercept the curved shape of the glass at right-angles, continuing their path as straight lines. When selecting equipment, a dome port must be carefully matched with the focal length of the lens in order to produce a focused image. Additionally, the lens in question must be able to focus reasonably close. In some cases, a diopter close up lens may have to be fitted to the camera lens.

Another important factor that must be considered in relation to underwater filming is lighting. With photography on land, many of us are accustomed to shooting in the early morning and late afternoon, generally avoiding the harshness of the midday sun. With underwater filming, the opposite is generally true with regards to the optimum time of day to undertake photography. Midday is usually preferred as there is often enough light underwater for decent aperture settings. Additionally, water acts like a diffuser to sunlight, scattering light rays that penetrate through the surface and creating a softer light. When the sun is directly overhead, the majority of the light will enter the water. When the sun is closer to the horizon, light rays strike the water?s surface at a sharper angle and much of this light is reflected. Thus filming underwater by available light is highly restricted at the beginning and end of the day.

Filming in deep water brings it?s own set of challenges in relation to lighting, namely that of color absorption. Water has an unusual effect on the color spectrum as certain colors are absorbed at certain depths. Red is the first color to disappear at approximately 12 feet. At 20 feet, orange will be completely absorbed, followed by yellow at 40 feet. At 65 feet, green will disappear and only blue will remain. Unless you want your footage to have a blue monochrome look for an atmospheric effect, it will be necessary to use some form of artificial lighting to restore the colors lost through absorption.

When using artificial lights, one should avoid pointing the light source directly at the subject. Besides producing very flat one dimensional lighting, such a straight on approach will result in backscatter. Backscatter refers to white specs floating around in underwater footage that are a result of light reflecting off the various particles suspended in the water. In low visibility conditions, backscatter can resemble snow. Positioning the light at an angle to the subject means that only the sides of the particles will be lit, minimizing the effect.

Finally, it is vital that you rinse the equipment in fresh water after use to avoid corrosion. This should be done as soon as possible after a dive. Keep the gear submerged in fresh water for a minimum of 20 minutes and move all moving parts to get rid of any salt that has deposited itself in any nooks and crannies.

Edited December 8, 2006 by Patrick Cooper