How to - Photography

So you want to take pictures underwater, well it's not that hard. The first thing to do is decide on which camera you want to use. There are three kinds:

1. A purpose built underwater camera such as the Sea & Sea camera (MX5, MX10, MX IIex) or the Nikonos camera. The advantage of these over the other options is that a flood in the camera does not mean the camera is destroyed, most service centres can have it back like new in no time. Also second hand units are available reasonably cheaply, but be careful getting a second hand unit unless you know what you are looking for. The disadvantage of these cameras is there is a lot of guess work with the focus and exposure settings, as you do not view your subject through the lens of the camera but through a view finder on top of it. They are also not as good as the other types out of the water.

2. A housed SLR (film based) camera, this is a normal land based camera enclosed in a water proof housing, most professional photographers use these. With these cameras you focus and frame your subject through the lens so you get to see exactly what you are taking a picture of. Beware not all land based cameras have housing built for them, so decide on a housing first and then buy the camera. The housings for these cameras are however priced out of all but the serious photographers reach.

3. A housed digital camera, these cameras are starting to make a big impact in the diving scene. They are simular to a housed SLR but with a digital camera. You can therefore take as many shots as you want and preview them before moving on and with no film to waste it will pay for itself in no time. These cameras have been marketed for all levels of photographer with the very pricey pro models and the reasonably priced amateur models. These cameras however do not like water and if your housing leaks your camera will more than likely need replacing, this can be all but eliminated with a careful maintenance plan.

If you are looking to replace your old purpose built camera for a housed digital camera, the reasons for this are two fold; the first being the cost of film and developing and with only 15% of the photo’s being good ones it was an expensive hobby. The second, being frustrated not knowing if I had that great shot or not, at least with a digital you will know right there and then if it’s any good.

A few terms used in photography and how they relate to underwater use.

F/stop
Refers to how much light is allowed to enter the camera. It is a diameter measurement of the iris of the lens and is called the aperture. The smaller the opening (aperture) the less light you let in and visa versa. F/stop is expressed as F/2.8, F/4, F5.6, F8, F16, F32 etc. Using a low F/stop (f/2.8) will open the iris up and will focus close but blur or black out distance or background objects. Using a high F/stop (F32) will close the iris down and will allow focus on objects close and far. You will however require more light when using a high F/stop.

Low F/stop	High F/stop

Focal length
This is the length of the camera lens. The longer the length the more narrow the field of view is. A 12mm lens will see 167 degrees while a 16mm will see 91 degrees and a 20mm will see 80 degrees. The wider the angle of view the closer you can get to the object with your camera and still keep the whole object in the frame. This helps decrease backscatter and is the main reason people buy wide angle lenses.

Shutter speed
This is how fast the film is exposed to the available light coming into the camera. Shutter speed is expressed as 1/8, 1/15, 1/30, 1/60, 1/90, 1/125, 1/250, 1/500 etc. The larger (slower) the shutter speed (i.e. 1/8 is the largest) the more moving objects tend to blur. If you use 1/8 on a moving car the whole car will look blurred, if you use 1/500 you will see the car as if it had stopped on the road. If lighting is bad, a slower (1/8) shutter speed is required to allow more time for light to enter the lens.

Slow shutter speed required because bad visibility stopped strobe (flash) use	High shutter speed required due to high speed fish movement

Depth of field
This is how much is in focus. The depth of field is the range of distance where an object is sharpest. It is dependent on the size of the aperture used. The smaller the aperture (eg; f22), the greater distance in front of and behind the subject that will be in focus. Just as a large aperture (say f5.6), results in a very narrow depth of field, that is only the subject or part of it, will be in focus. This can be used to give a background that is blurred, thus providing emphasis only on the subject photographed.

Film Speed
This is how sensitive film is to light. The higher the number the more grain you see in your picture. At 800 ISO the image will have a fair bit of grain showing, at 50 ISO you will not see any.

Manual mode:
This is where you have total control over F/stop, aperture size and shutter speed. You can vary the exposure however you wish.

Aperture Priority Mode:
This mode allows you to set the aperture or f/stop of the lens and the camera will automatically set the shutter speed. This mode is great for macro work as you have full control over the depth of field.

Shutter Priority Mode:
This mode allows you to set the shutter of the camera and the camera will automatically set the aperture of the lens. If you wish to take pictures of fast moving fish this may be the option to use as you can set the shutter speed to a fast level to effectively freeze the fish in motion

Auto Mode:
In this mode the camera will set everything for you. However in low light the camera may choose a longer shutter speed thus making moving object blurry.

What should I focus on?
Objects appear much closer and larger in water than they do in air, actually it is 33% larger and 25% closer. So when focusing your camera as the lens works the same as your eye you must focus for what the distance "appears" to be. That is if you actually measured the distance between the subject and your lens, you would be focusing 25% (1/4) closer than the measured distance.

Where do I point my strobe?
With the strobe on the left hand side of the camera and having the light illuminating the subject from about a 45° downward angle but because of this position, the flash usually lights up any suspended particles in the water and this will detract from an otherwise acceptable photograph. Two ways to overcome it are;

Either shoot directly at the reef scene and loose the backscatter (and probably the subject) in the background.

Keep low and shoot upwards but instead of having the flash pointing down, hold it low and pointing upwards towards the subject, the result will be well balanced lighting with a blue background and any backscatter will be lost in the foreground. Even in the most turbid water the results can be surprising.

How do you do, a Macro shot?

Macro photography is probably the way most of us start out. Because it is easier to approach the subjects, the camera is a lot more simple to use and we get quick results. But a lot of photographers still treat a macro the same way most people take shots of kids, that is at a downward angle. This results in a good record of the subject but a flat and uninteresting picture. To overcome this get as low as is possible and shoot from either side on or at least at a 45° angle which will give it a more three dimensional perspective.

What do I do?... My Camera has flooded!!!

For a major flood
Remove the batteries immediately to avoid explosive gas build-up from the shorting batteries and to prevent further circuit board damage. Remove the sea water as soon as possible, rinse thoroughly in fresh water, if close to a repairer, leave the unit immersed in fresh water, if possible dismantle lenses etc to allow fresh water to penetrate as much as possible. If item cannot be left in fresh water, dry thoroughly and get to a repairer as soon as possible.

For a lesser flood
Remove batteries and remove lens if unaffected. Check body, if circuit board has not suffered water damage, DO NOT WET IT FURTHER. If only a drop of water has entered, wipe out with lens tissue, dry unit thoroughly and do not test again until completely dry. Be extremely careful of the delicate shutter mechanisms. Have unit serviced.