Side-lighting can be very atmospheric.

Flash power

When you find the built-in flash on your compact camera limiting your creativity, its time to invest in an external unit. Mark Koekemoer explains why

hspace=5 BACK IN THE APRIL ISSUE, I discussed the use of the cameras built-in flash and the limitations it imposes in terms of power, which affects range; coverage for even lighting; and backscatter, caused by particles directly in front of the built-in flash.
Because this flash is fixed to the camera, you are also limited as to how creative you can be with your lighting. This month Ill guide you on choosing an external flashgun, and provide some tips on getting started. Flashgun and strobe have the same meaning, incidentally.

People often tell me that they want to purchase a flashgun but not a powerful one, because theyre not photographing big stuff, or because theyre not professionals.
Well, having a powerful flashgun has nothing to do with being professional. The power of the flash, given in the form of a Guide Number (GN), is often misunderstood or overlooked. Always use a GN calculated in air to compare flashgun power.

The relevance of power to your underwater photography is the effect the aperture has on the range of your flash. The smaller the aperture you use, the shorter the range. The larger the aperture, the greater the range.
Most high-power flashguns have an effective range of about 2m for reproducing good colours.
If you have a low-powered flash, and the hawkfish wont let you any nearer than that, it is unlikely that your flash will illuminate the fish.
Or take a nudibranch. You may want to have great depth of field and use a small aperture of f8, in which case your flashgun will need to be powerful enough to light up the nudibranch while using a very small aperture.

Light emitted from the flash falls off very quickly under water, so when selecting a flashgun, make sure that the coverage of the light beam complements the angle of the lenses you are using.
You may not start off with a wide-angle lens, but it is wise to anticipate that you will eventually invest in one. So make sure the flashgun of choice has a beam coverage of around 100°.
This will ensure even lighting across the photo, and eliminate harsh shadows. An opaque piece of plastic called a diffuser can also be used to spread the light a little further.

It is important to make sure that the flashgun and the camera communicate reliably between themselves, so that they are synchronised and the flash fires every time. If firing is intermittent, it may cost you dearly in photographic opportunities.

Some flashguns operate on a slave function, which relies on the light from the built-in flash bouncing off the subject and triggering the external unit.
The slave system is known to be unreliable.
The quality of the slave sensor and of the water affects the reliability of the flash.
As the slave relies on the built-in flash, you will get backscatter, which defeats the purpose of investing in the external flashgun.
By far the most reliable method for triggering the flashgun is a fibre-optic cable.

The flashgun also needs to be able to synchronise itself with your cameras flash settings. Some compacts have a pre-flash before the main flash is fired, in which case your flashgun needs to be in sync with the two flashes.
However, in some cases, such as with a Canon compact, a pre-flash is fired in most modes other than manual. In this mode, the Canon fires only once. This means that your flash must be able to accommodate for this change in synchronisation.

It would seem obvious to aim the flashgun directly at the subject, but refraction causes a subject to look 25% bigger and closer than it really is.
So by aiming directly at the subject, you are actually lighting the column of water between the lens and the subject, resulting in backscatter.
The flash should be aimed one-third behind the apparent subject distance. As a guide, for close-up photography use the 12 oclock position directly above the camera housing, keeping the face of the flash in line with the lens.
When using the built-in lens, raise the flashgun roughly three fists higher, and angle it slightly upward. The edge of the beam will catch the subject.
As the angle of the lens you use gets wider, the higher you should raise the flashgun.
When using wide-angle and super wide-angle lenses, make sure that the face of the flashgun is slightly behind the plane of the lens, to prevent hot-spots of light entering the edges of the photo.

Always try to capture your subject in a different light. By doing so you may capture the creatures personality better, or create a certain mood to your photo.
Side-lighting means moving the flash over to one side, so that you illuminate the side of the face and leave the other side in shadow. This method is particularly effective in portraits, in the style of the Dutch painter Rembrandt.
Back-lighting involves aiming the light from behind the subject, creating a backlit effect.
Back-lighting works well with filamentous, translucent subjects, or for sharply outlining hairy, feathery edges or tentacles of a subject.

Snoots are tubular devices that come in various diameters. They attach to your flashgun and work by narrowing the beam to create a spotlight effect.
Snoots are used to highlight a specific area of a subject, such as the eyes.

Next month - (October issue): The ins and outs of your compact.

hspace=5 Yellow eel is a winner
Septembers Photocall Competition to suit the theme Creative Lighting is this strikingly-lit ribbon eel portrait taken by Daniel Norwood of Gravesend, Kent, using a compact Fuji FD50 camera and housing.

Daniel wins a £300 INON UK voucher redeemable against lenses, flashguns or accessories at any official INON UK product centre.

Have you uploaded yet
Our online PhotoCall competition gives you the chance to upload your best work to, and to win not only wider exposure and monthly prizes but, ultimately, a wonderful fortnight in the Philippines.
Each month at we offer you a theme, and invite you to upload up to three images. Mark Koekemoer selects the winning image, reproduced both online and in DIVER.
After a year, when 12 winners have been picked, their work will be judged to find the grand prize-winner. The prize A two-centre, two-week trip to the Philippines, including all flights, full-board accommodation and unlimited diving, worth £2800!
This great prize is offered by Atlantis Dive Resorts, which has centres in two prime diving locations, Puerto Galera and Dumaguete, and runs the annual Atlantis Foto Festival.
The winner will join Mark Koekemoer on an INON UK group trip to the festival in summer 2011, and Diver will reproduce the results of his or her diving experiences.

 The theme for September entries is -
Choosing and using flashguns with compact cameras.

Help on uploading your photos - PLEASE READ CAREFULLY

  1. You need to be registered on the Divernet Forums. If you are not registered and logged-in then you will be asked to do so when you click on ENTER above. Complete the registration form selecting your username and password. There may be a delay before your registration is confirmed while our filter checks that your registration request comes from a real person! As soon as you receive your confirmation you can proceed with the upload of your photos by going to the upload page. If you are already registered with the Divernet Forums you can go directly to the upload page.
  2. Select your photo file from your own computer using the Browse button. Make sure it does not exceed 600pixels in width or height.
  3. Give your image a title and CHANGE THE FILE NAME so that we can connect it to your entry details.
  4. Add a description - location, subject, your NAME if you want to take full credit for the photo, etc.
  5. Select the category you are entering - this will need to be the correct category for the monthly competition, such as March 2010 PhotoCall Competition - Peak of the Action for the March competition.
  6. Add some keywords which would help people find your photo (e.g. include your name, the location, etc.)
  7. Add your registered username so that we can identify you if your photo is selected as a winner.
  8. Hit the Submit button. You may submit up to 3 photos in each monthly competition.

Please study these terms & conditions:
  • Submitted images must be taken on a digital compact camera
  • Only images that have not previously won a place in a photo competition are eligible for the competition.
  • Images uploaded must have a maximum width or height of 600 pixels.
  • Entrants must have their own hi-res version of the image available in case of short-listing.
  • Entrants retain the copyright on their images, but by entering the PhotoCall competition automatically grant permission for Diver and Divernet to publish winning photographs.
  • The grand prize-winner must be available to travel at the times stipulated during the Atlantis Foto Festival, between June and 20 August 2011.
  • If the winner wishes to bring a companion and share a room, normal double-occupancy rates will apply to that second person.
  • The winner agrees to provide any images taken during the festival for subsequent publication in Diver and on Divernet and the Atlantis and INON UK websites.
  • The prize is strictly non-transferrable.
  • This competition is not open to staff, family or commercial associates of Diver Group, Atlantis Dive Resorts, Inon UK or associated companies.
  • In all judgments, the judges’ decision is final.