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Underwater Photography Essentials: Part 3



Underwater Photography

Tips, ideas and advice for budding underwater photographers

by Nick Robertson-Brown FRPS

Part 3: Getting to grips with your camera settings – ISO

Read Part 1 of Underwater Photography Essentials here.

Read Part 2 here.

Underwater Photography


The third element in controlling the exposure value is the ISO. The term ISO is an acronym for the International Standards Organisation which prescribed a common standard for the sensitivity of a film many years ago. The higher the ISO number, the greater the sensitivity to light; but it came at a price. As the sensitivity to light improves and the ISO number on the film gets higher, the lower the quality of the image becomes. With a high ISO film, the image looks grainy and hence the resolution is reduced. The same standard has been maintained in digital imagery, whereby the exposure value of a digital image will be the same as it is on a film camera, as long as all the settings are the same. There are, however, still penalties as you increase the ISO value. In much the same way as it did on film cameras, the image becomes grainy, but we refer to this as noise – and a noisy image has very restricted uses.

Underwater Photography

On the face of it, it would appear that increasing the ISO is a great way to increase the exposure value of your image with no major side-effects. Only a few years ago, using the ISO as part of the exposure triangle was restricted to changes between ISO 100 and ISO 800 (at best). Modern technology has come a long way in the last 4 to 5 years and on some cameras, mostly expensive ones, ISO values of 2500 can produce images with very little noise.

With the introduction of modern technology, the ISO setting is now a serious tool to be exploited underwater, as high ISOs are ideal for working in low light conditions. The ability of an individual camera at different ISOs will vary between manufacturers and camera models and it is important that you understand the limitations of your own camera so you know how far you can push the limits of the ISO setting. You can test this limit by taking a sequence of images into shadow and increasing the ISO on each shot. The low ISO image should look clean and black, whereas the high ISO image will look really noisy with hundreds of tiny red or blue dots which become clearly apparent when you zoom in. By taking a sequence of images, you can look at the effect as you increase the ISO, and you can decide how high an ISO value you are happy with. There is a certain amount of subjectivity in this, but it is what you think that is important.

Having the ISO set to the right value is still important, despite the advances in technology. Ideally, the default setting should be at your lowest ISO setting, which is usually 100 and this means your images will give the best resolution of your camera can produce. Whilst an image which you have taken at ISO 400 for example, may look as good as the one you took at 100, when you zoom in, and look really closely at it, you will appreciate the higher resolution of ISO 100.

One point I should make about using the ISO at high values, is that on certain images, the noise can actually work, possibly even enhancing the result. However, this is unusual, and increasing the ISO level should really only be used if reducing the shutter speed would induce motion blur or shake, and opening the f-stop would reduce your depth of field beyond the level you are comfortable with.

Underwater Photography

This image of the wreck of the Giannis D is shot with a high ISO (1250) on a Nikon D800, so whilst there is some noise, it suits a wreck shot.

Now that we have discussed all three factors that affect exposure control, pick up your camera, put it into manual, and start to experiment.

Whilst we are dedicated Nikon camera users, we found this useful tool on the Canon website and thought it was worth posting. You do not even need to get your camera out to see how ISO, Aperture and Shutter Speed interact – as you can give it a go on this handy web tool whilst sat at your computer:


Nick bookDo you want to learn more? You can pick up a copy of Nick’s book “Underwater Photography Art & Techniques” by clicking here. For a signed copy, click 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 Dive Ambassadors for The Islands of The Bahamas and are supported by Mares, Paralenz, Nauticam and Olympus. To find out more visit


Emperor Divers reaches halfway in Covid Diver Heroes Initiative with fourth award



Emperor Divers have reached the halfway point with their #coviddiverheroes initiative and are still receiving worthy nominations every day! Here, they recognise their 4th winner, another awesome hero from the diving community with an inspirational story of selflessness through the pandemic. Nominated by David White, Phuong Cao wins a free liveaboard trip in the Maldives when she can finally take some time off, and here is her story:

I, David White, would like to nominate Phuong Cao (36) for her tireless efforts fighting this pandemic. Not satisfied with being a frontline hospitalist in New York she took a second job on the COVID team in Guam to treat patients under even tougher conditions on her weeks off! She continues to commute 7750 miles each way and apply herself to both jobs for three months already and counting. Her energy level has no limits and she’s only happy when those in her care are on the mend. I think she definitely deserves a break! I guess the Maldives would be the best choice for her as I know she has dived with you in the Red Sea already.

Phuong Cao

We have been in touch with Phuong who had this to say: “Wow what a surprise! Thank you for the recognition. Holding my breath until I get back underwater!”

The halfway point is a good chance to remind people that the initiative is still running and the Emperor Divers team would love to hear about more heroes, as there are four more to award in the next 2 months!

Do you know a diver who has been heroic this past year? Emperor know that, worldwide, people have had to step up during this pandemic which has affected so many lives. They want to reward some real heroes with free liveaboard trips in the Red Sea or Maldives.

Luke Atkinson, Emperor’s Red Sea Manager, said: “This initiative is our way of saying ‘thank you’ to all those hundreds of people who have taken a selfless interest in looking after the vulnerable in their community. Examples could include healthworkers, carers or those who have come out of retirement to volunteer locally, but really we know there are many other ways people have been heroic.“

Emperor want to hear from people who know a heroic diver who would love to have a free liveaboard trip to look forward to in the future. People need to nominate a Covid Hero Diver and tell Emperor (in 100 – 200 words) why they deserve a free trip, and whether they would prefer the Red Sea or the Maldives. A multinational panel of Emperor’s most loyal and compassionate staff will judge the entries and pick a winner every 2 weeks for the next 2 months. There are two remaining Red Sea and two more Maldives liveaboards to be earned, so get nominating and give that hero a reward for their amazing work!

Winners will be announced by 14th (Maldives) and 28th (Red Sea) of each month. Final entries for Red Sea by 20th May ‘21 and Maldives 5th June ’21.

Entries, comments and questions should be sent to

Terms & Conditions apply: Please contact for details.

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Dive Training Blogs

My Dive Buddies Episode 1: Alejandro Dutto’s Best Wreck Dives! (Watch Video)



My Dive Buddies Episode 1: Alejandro Dutto’s Best Wreck Dives!

The first in a new series, where I invite my local scuba diving buddies into the Dive Locker for a beer and a chat! This week I’m chatting with Alejandro Dutto, Co-Founder of the International Scuba Divers Club and Publisher of the digital scuba magazine ‘Trim.’ I know Alejandro is a man after my own heart. Before covid hit, we dived South Florida wrecks together frequently and I’m looking forward to getting back in the water with him.

But for now, I’m happy to have a beer with him and talk about our top three favourite South Florida Wreck Dives. Alejandro also talks about the challenges of filming at technical diving depths and about his new Spanish language dive magazine.

Please follow Alejandro’s channels here:

Thanks everyone! D.S.D.O James

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Explore the amazing triangle of Red Sea Reefs - The Brothers, Daedalus and Elphinstone on board the brand new liveaboard Big Blue.  With an option to add on a week at Roots Red Sea before or after. 

Strong currents and deep blue water are the catalysts that bring the pelagic species flocking to these reefs. The reefs themselves provide exquisite homes for a multitude of marine life.  The wafting soft corals are adorned with thousands of colourful fish. The gorgonian fans and hard corals provide magnificent back drops, all being patrolled by the reef’s predatory species.

£1475 per person based on double occupancy.  Soft all inclusive board basis, buffet meals with snacks, tea and coffee always available.  Add a week on at Roots Red Sea Resort before or after the liveaboard for just £725pp.  Flights and transfers are included.  See our brochure linked above for the full itinerary.

This trip will be hosted by The Scuba Place.  Come Dive with Us!

Call 020 3515 9955 or email

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