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Underwater Photography Essentials: Part 1



underwater photography

Tips, ideas and advice for budding underwater photographers

by Nick Robertson-Brown FRPS

Part 1: Getting to grips with your camera settings – Aperture

When you look at your subject underwater, without using artificial light, there are essentially three factors that you can change on your camera to create the image you want. These three factors are aperture, shutter speed and ISO and all three have an effect upon how the image will look. Each will have their own individual characteristic upon the outcome of your image, and usually, by changing one of these factors, one of the others will need to be adjusted to compensate for what you have done. In order to maintain the same amount of light in your image, the exposure value (EV), increasing the light from one of these factors will mean you need to decrease the light using one of the other two.

underwater photography

It is a case of balancing the light to get the right value for the image you want to create. How you balance this value will give you, the photographer, control of how you wish the image to look. In this first article, we are going to look at Aperture.


The aperture is the space behind the lens through which the light enters the camera, and hence, the sensor. The aperture works very much in the same way as the pupil of the human eye. In bright light, the pupil will close down to a small round opening, hence restricting the amount of light that falls on the retina. As it gets darker, the pupil dilates to allow more light to enter the eye. The aperture of the camera’s lens can be opened and closed, just like the pupil of the eye, and if you have your camera in the auto setting, this is one factor the camera may use to change the exposure value. This is why I think it is important that you should use the manual setting so you have control of how you want to present your image.

Aperture Setting

The aperture setting is referred to as the f-stop or f-number, and the smaller the number, the larger the aperture. Mechanically, the size of the hole is determined by a circle of blades that cause the central aperture to open and close by the overlapping of these blades on each other. Closing the aperture will restrict the amount of light hitting the sensor and the f-number increases. This f-number is not just a random figure, but is in fact a ratio of the focal length of the lens to the physical size of the aperture. In most compact cameras there is no mechanical closing of an aperture but its attributes are produced electronically to give the same effect.

underwater photography

The figure above shows the f-value and all camera lenses are calibrated using the same f-stop scale. The range of aperture numbers does vary from one lens to another, with the greater range generally equating to the greater price. The scale, however, is always constant and each increase in f-stop number equates to half the amount of light that is allowed through to the sensor.

Depth of Field

Opening and closing the aperture, or decreasing and increasing the f-stop, would appear to be a simple way of changing the light level on the sensor. As the aperture is opened however, the depth of field is reduced, and this has a very noticeable effect upon the image. The depth of field is defined as the amount of the image which appears to be acceptably in focus, and changing the depth of field on your subject can create very different images.

underwater photography

As you can see from the above image, the pygmy seahorse is in sharp focus. The rest of the coral behind it is totally out of focus, and this has the effect of making the seahorse, your subject, pop out from the picture.

And again with this ghost pipefish, the subject is in focus, but the background is blurry and there can be no misunderstanding as to what the subject is.

underwater photography

This does not necessarily mean that you should always use a small depth of field to make your subject pop out, and there are times when the environment around the subject is important. This technique is used by many underwater photographers as it allows you to virtually eliminate any messy background by using a low f-stop number to create a small depth of field. This is ideal for when your subject will not come out into the open. The blurry background in an image is called “Bokeh”

Of course, sometimes you want to show the critter in its environment and to do this, you need to increase the f-stop (close down the aperture). As a result of closing down the aperture, the exposure value will go down as you are letting less light onto the sensor. Within the exposure triangle, there are two other factors you can adjust and I will be looking at these controls next time.


underwater photography

Do you want to learn more? You can pick up a copy of Nick’s book “Underwater Photography Art & Techniques” by clicking here.

Underwater Photography Courses

Contact Nick for information on the Frogfish Photography Complete Underwater Photography Award, designed for 1:1 and small group sessions to improve your underwater photography at your pace.underwater photography

           |  | +44 (0)161 9177101

Nick and Caroline (Frogfish Photography) are a married couple of conservation driven underwater photo-journalists and authors. Both have honours degrees from Manchester University, in Environmental Biology and Biology respectively, with Nick being a Fellow of the Royal Photographic Society, a former high school science teacher with a DipEd in Teaching Studies. Caroline has an MSc in Animal Behaviour specializing in Caribbean Ecology. They are multiple award-winning photographers and along with 4 published books, feature regularly in the diving, wildlife and international press They are the Underwater Photography and Deputy Editors at Scubaverse and Dive Travel Adventures. Winners of the Caribbean Tourism Organization Photo-journalist of the Year for a feature on Shark Diving in The Bahamas, and they have been placed in every year they have entered. Nick and Caroline regularly use their free time to visit schools, both in the UK and on their travels, to discuss the important issues of marine conservation, sharks and plastic pollution. They are ambassadors for Sharks4Kids and founders of SeaStraw. They are supported by Mares, Paralenz, Nauticam and Olympus. To find out more visit


BSAC launch #DiscoverUKdiving video competition



BSAC is launching a new video competition which aims to get the diving community sharing and discussing the highlights of UK diving to inspire others to give it a try and discover it for themselves.

They are inviting you to share short UK diving or snorkelling videos – tagged #DiscoverUKdiving or #DiscoverUKsnorkelling – to be in with a chance of winning a Fourth Element Hydra Neoprene Drysuit worth £999 (or an alternative non-diving suit if a snorkeller wins). There are other prizes up for grabs too, with a Fourth Element duffel bag going to second place and a year’s BSAC membership for third.

The #DiscoverUKdiving video competition aims to get the diving community talking about the highlights of UK diving and/or BSAC club life by sharing short videos to surprise and inspire others to discover it for themselves.

BSAC is looking for videos that show an exciting moment, unique insight or anything that exemplifies why diving in the UK is so much fun and can encourage others to take up UK diving. People will be invited to vote for the entries they find most inspiring on the competition gallery website.

BSAC CEO Mary Tetley said: “We want to show others who haven’t experienced UK diving why we love it so much, and we need your help! Use your phone, GoPro or pretty much anything to share a short video that encapsulates why you love diving in the UK. Ideally, showing off UK diving the BSAC way!”

The competition will be open for entries until midnight on Monday 30 November.

The videos can be either be above water (e.g. a RIB ride out to a dive site), below water (e.g. exploring a wreck with your buddy) or a combination of both. Each video should be short (no longer than 15 seconds) and you can enter up to three videos. The winner will be the entry that receives the most votes. Voting will remain open for a further week and close on Monday 7 December. The winners will be announced the week of 14 December, good luck!

Full terms and conditions, including how to enter as well as how to vote on your favourite video can be found here.

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Henley Spiers: Black & White Photography at the September NUPG meeting (Watch Video)



The September NUPG meeting saw Henley Spiers take to the virtual stage. Henley decided to divide the evening into two topic areas for discussion: Black and White Photography and Pelagic Encounters – his two biggest passions in underwater photography at the moment.  Henley showed off his stunning black and white images to the NUPG audience, talking about why he selected each image to convert to monochrome and was generous enough to share the photoshop techniques with the group too. He then went on to wow the group with images from the deep blue sea, with some simply stunning pelagic encounters. 

As always, the NUPG members also had a chance to show off some of their images in the monthly competition. This month’s theme was “Invertebrates” and it saw a range of ideas and images from the group.

The winning shot of a sea lion was taken by Maggie Russell

The runner-up was by John Spencer

Third place was taken by Justin Beevor

The next meeting was held on Monday 12th October, a talk from Simon Rogerson: Difficulties with Sharks. Check back soon for the video!

For more information about the NUPG please visit the website by clicking here.

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