Underwater photography tips



Australasian gannet above and below - Popes Eye, Port Phillip

Before contemplating underwater photography you must be comfortable in the water. Great buoyancy skills and the ability to dive without kicking up sand are essential. You must also be able to dive one handed, the other hand will be holding the camera. It also helps if your dive sites have calm water, lots of co-operative critters and great vis, which is unusual in sub-temperate southern Australia.

The basics
Move in as close as possible
Move the flash away from the camera

Exposure
Use flash power and position to adjust forground exposure
Use aperture to adjust overall exposure
Use shutter speed to adjust background exposure

More advanced tips
Better lighting
Aperture priority with manual flash
Manual focus with framers
Pre focus
Black and white underwater



The basics

Move in as close as possible

If you can't reach out and touch your subject you are too far away.

I'm sure you don't believe me but if you want bright, sharp, colourful images you must get as close as possible to your subject. This is the major difference between above and under water photography.

The composite photo of an Australasian gannet above shows the difference between air and water. As soon as you go below the surface, brightness, warm colours and visibility are lost.

Water is 800 times denser than air and consists of microscopic particles like water molecules, plankton, silt and a stack of other things you probably don't want to know about. Water molecules absorb warm colours and all the other particles cause haze and backscatter.

You have to consider that you're also photographing all that water, plankton, silt and crud in front of your subject.

For sharp colourful results you must minimize the amount of water between the camera and subject.

This principle is the same for all underwater photography, whether using the cheapest disposable or the most expensive housed digital SLR. Most underwater photos are taken at a distance of less than 1m from the subject, close-up shots are usually closer than 50cm and macro shots are closer than 20cm.


distance 1.5m, no flash

distance 30cm, no flash
Move the flash away from the camera

The second big step to getting great underwater photos is to buy an external flash, giving much better control over lighting.

Water molecules, plankton and suspended particles act as a blue/green filter that increases with distance through the water. This filter effect reduces red, then orange, then yellow light leaving green and blue.

If you want to capture bright colourful images at depths below a few meters you need to replace this lost light by using a flash. However, the flash will also illuminate all the particles in the water, causing backscatter (bright blurred spots in front of your subject).

If you are just using the camera flash then backscatter will be a problem. Good clean shots will be impossible unless you are in crystal clear water or very close to your subject.

Moving the flash further away from the lens will avoid illuminating particles between the camera and subject and may produce more interesting lighting.

A good starting point is to move the flash the same distance away from the lens as the subject distance.


backscatter

less backscatter


Exposure

If your setup is fully automatic all you can do is aim the camera, push the button and hope for the best. You may be lucky and capture the odd decent shot.

However if you are serious about underwater photography you need to take control and use manual exposure settings. It's not as difficult as it may seem. Eventually you will have a couple of standard settings for macro and wide angle.

Here are my Compact Camera settings: ISO 100
Macro: Shutter speed 125, Aperture 7.6
Wide angle: Shutter speed 60, Aperture 4.0

Here are my SLR Camera settings: ISO 200
Macro: Shutter speed 125, Aperture 22
Wide angle: Shutter speed 60, Aperture 8.0

I then make adjustments starting from these proven settings.
I usually leave the aperture alone and adjust the flash power to expose the subject correctly and adjust the shutter speed to expose the background how I want.
These adjustments are explained in more detail below.

Use the aperture to control overall exposure

You actually have two light sources underwater. The first being flash and the second being ambient (sunlight penetrating down from the surface). By adjusting the aperture you adjust the overall exposure of both the flash and the ambient light.

Compact digital cameras usually have apertures from 2.8 (largest aperture) to 8.0 (smallest aperture)


aperture f/3.3, 1/30th sec

aperture f/5.2, 1/30th sec

aperture f/8, 1/30th sec
Smaller apertures such as f/22 (SLR), and f/8 (Compact Digital), give more depth of field. Larger apertures like f/2.8 give shallower depth of field.


Use flash position and power to control foreground exposure

By turning the flash power up or down you can lighten or darken the subject (or foreground exposure) without changing the background exposure. Moving the flash closer to or further away from the subject achieves the same result.

My Inon Z220 can be adjusted from full power to -5.0 stops.

More recent models can give Auto flash exposure (S-TTL) by mimicking the camera flash. This usually works for macro photography but not so well for wide angle.


Less flash darker subject

Correct flash power

More flash lighter subject


Use shutter speed to balance background exposure

Shutter speed only affects exposure due to ambient light. This is because the flash duration is usually much shorter than the shutter speed.

When you take a shot, the shutter opens, then the flash fires in a very short burst, then the shutter closes. So adjusting the shutter speed does not alter the amount of flash delivered.

This means you can set the flash and aperture to correctly expose the foreground subject then adjust the shutter speed to make the background go from black through to bright blue/green. The choice is up to you.


Fast shutter speed

Mid shutter speed

Slow shutter speed
Flash sync speed
With the Nikon D80, speeds faster than 1/250th cannot be used with flash because the flash will only expose part of the scene. This is because the shutter blinds never fully open at speeds faster than the "Flash Sync Speed" of 1/250th. Check the Flash Sync Speed of your camera to determine the fastest usable shutter speed. Most compact digital cameras can use all shutter speeds with flash. This is one of the advantages they have over SLRs



Advanced techniques

External strobe positioning
Most single flash heads sit above and to the left of the lens. This is not always the best position. Much of the time you will be lighting up the fish's tail or the back of the nudibranch.
Moving the single flash to center above the camera will improve the lighting to some extent. However, the most flexible and creative method is to disconnect the arm and hand hold the flash in the best position. You can light up faces or give more dramatic cross lighting which will bring your subjects to life.


flash above left

flash above right
Two strobes
Single strobes will always produce dark shadows, which is not always a bad thing. However, if you want total control over lighting then you need two strobes. The second strobe is used to produce more even illumination by adding light into the dark shadow areas.

Of course an extra strobe costs more, weighs more and is harder to handle underwater. It's best to master the single strobe before taking this next step.



Aperture priority with manual flash
This is a great technique for photography in shallow water with lots of ambient light.
With the camera on aperture priority, you select the correct aperture for the flash and the camera calculates the shutter speed depending on the ambient light. I find it's a good idea to dial in some "minus EV" (1/2 to 1 stop) for a darker background.



Manual focus
If you're totally frustrated with slow or impossible auto focus why not revert back to Nikonos methods. Manual focus gets rid of the autofocus delay making it easier to shoot moving fish, at low light levels, and even at night.

Wide angle
Using a wide angle lens and f/8 (smallest aperture on compact cameras) set the manual focus on about 0.20m (experiment to find what works for you) and everything will be focussed from about 15cm to infinity.

Macro
With the Nikon Coolpix 5000 I could set manual focus to 0.07m and long zoom, then move the camera forward until the subject is in focus on the screen. This method is a little difficult because you need good eye-sight and no bright light on the screen to be able to pick when it is sharp.

Using framing prongs
This is an easier method for macro manual focus. Using framing prongs of the correct length and width guarantees sharp results as long as you can keep the subject between the framers.


Click here for a macro framer design giving horizontal coverage of 30mm.

Pre focus
I often try to photograph seadragons or bluedevil fish under ledges in the deep shadows. Auto focus does not have a hope in this situation unless you shine a bright torch on the subject.

However you can use a temporary form of fixed focus which means you don't need the torch.
Pull back in to brighter ambient light and half press the shutter to focus on something bright. Hold the shutter lever there and move back under the ledge, line up the subject at roughly the same distance as the bright subject and shoot.

You will have greatest success with wide zoom and small apertures when using this method.



Black and white ambient light photography
If you're photographing wrecks you will not be able to light up the whole wreck with your flash so most of your images will be illuminated only by ambient light. This means they will be predominantly low contrast monochrome blue or green images.
Wrecks look great in black and white and you have much more scope for enhancing contrast without worrying about retaining realistic colours. Many other subjects with little colour and good tonal range may look great also.
Digital images can be desaturated and the contrast adjusted either at the time of shooting or on the computer. 

It is also so much easier to use the camera on Auto exposure and not have to worry about flash settings for a change.


Colour capture

BW, contrast increased
Click here for a gallery of Black and White underwater images.




inside the J4 sub

giant cuttle - queenscliff

weedy seadragon - queenscliff