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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 Robertson-Brown are a husband and wife team of underwater photographers. Both have degrees in environmental biology from Manchester University, with Caroline also having a masters in animal behaviour. Nick is a fellow of the Royal Photographic Society in underwater wildlife photography and he also has a masters in teaching. They are passionate about marine conservation and hope that their images can inspire people to look after the world's seas and oceans. Their Manchester-based company, Frogfish Photography, offers a wide range of services and advice. They offer tuition with their own tailor made course - the Complete Underwater Photography Award. The modules of the course have been written to complement the corresponding chapters in Nick's own book: Underwater Photography Art and Techniques. They also offer equipment sales and underwater photography trips in the UK and abroad. For more information visit


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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SeaLife launches new underwater housing for iPhone



SeaLife is introducing a new compact and lightweight underwater housing for Apple’s iPhone.  The new SeaLife SportDiver housing will allow divers to take photos and video with their iPhone down to 130 feet or 40 meters.  The SportDiver can encase iPhone 7, 7 Plus, 8, 8 Plus, X, Xr, Xs, Xs Max, 11, 11 Pro Max, and SE (2nd Gen) models.

The heavy-duty housing is constructed of Polycarbonate, stainless steel, aluminum and optical grade glass.  And while the SportDiver housing is “heavy duty”, it is not heavy, weighing less than 1.5 pounds (641 grams), and is lightweight for travelling and offers almost neutral buoyancy in water depending on which iPhone model is used.

The SportDiver is easy to hold and use and offers a large shutter lever and rear control buttons for easy operation, even with dive gloves.  Snorkelers and Divers can get more creative with their photos or video shot by using advanced camera settings. Adjust Zoom, Exposure (EV), Auto/Manual Focus, White Balance, Tint, Lens selection, RAW+JPEG mode, Live Photo and Background Blur (on available iPhone models).

The SportDiver housing includes the free SeaLife SportDiver camera app for iOS 12 and up and unlike other smartphone housing apps, there are no annoying in-app purchases or ads.  You can easily switch between photo and video mode.  The SportDiver App uses the iPhone camera technology native to each iPhone® model.

The App Playback mode shows full size photos and videos with vertical thumbnail strip to easily locate your images. Videos start playing automatically when selected. All files are also saved to iPhone camera roll.  The SportDiver housing automatically connects to your iPhone and the SportDiver app using Bluetooth® Low Energy (LE) 5 wireless technology. No cables or buttons touch the phone and offers ultra-low power consumption for both the phone and the housing which is powered by two AAA batteries that last over 50 hours of continuous use.

For enhanced imaging results, a removable underwater color-correction filter is included with the SportDiver which restores natural underwater colors.  The filter easily attached or removes underwater and includes a safety tether to prevent loss.  The SportDiver housing features triple 1/4-20 tripod mounts which mounts to any light or light tray with standard tripod threads such as SeaLife’s own range of Sea Dragon underwater photo/video lights.  SeaLife also offers the SportDiver and Sea Dragon underwater light combined dubbed the “SportDiver Pro 2500 Set”.

For the phone’s safety and protection, the SportDiver has a sturdy holding spring and rubber grip tabs that securely hold the iPhone® in place and add shock-protection.  The SportDiver has “Dual Leak Alarms” which include an internal moisture alarm and a vacuum pressure alarm which alert the diver with on-screen warnings, audio and LED signal in the unlikely event the waterproof seal is compromised and there’s a loss of housing pressure or moisture is detected.  The door of the SportDiver is sealed with a TPE O-ring and a robust cam-lock sealing latch that easily and securely locks waterproof door.  To prevent interior fogging from residual moisture, the SportDiver uses the anti-fogging agent “Moisture Muncher” capsule which prevents fogging and internal condensation.

Deliveries of the SportDiver iPhone housing are planned to start in November, 2020.

Item                Description                                                                                         US Retail

SL400               SportDiver Underwater Housing for iPhone                                       $299.95
SL401               SportDiver Pro 2500 Set with Sea Dragon 2500 underwater light    $649.95

Included with SeaLife SportDiver, Model SL400:

  • SportDiver Underwater iPhone Housing
  • Underwater Color-correction filter
  • Vacuum pump
  • Rubber Grip Tabs (12x Small, 12x Medium and 12x Large)
  • Spare O-rings (1x Main O-ring and 1x Vacuum Check Port O-ring)
  • O-ring lubricant
  • O-ring removal tool
  • Deluxe wrist strap with clip
  • Moisture Muncher sample pack (1 capsule)
  • AAA alkaline batteries (2)
  • EVA Carry Case

Included with SeaLife SportDiver Pro 2500 Set, Model SL401:

  • SportDiver Underwater Housing for iPhone, model SL400 as above
  • Sea Dragon 2500 Underwater Photo/Video light, model SL671
  • Sea Dragon 2500 Underwater Photo/Video Light head
  • Flex-Connect Single Tray w/ standard ¼-20 mounting screw
  • Flex-Connect grip
  • 25Wh Lithium Ion rechargeable battery
  • AC Power Adapter, charging tray, and international plug adapters
  • Spare O-rings, O-ring lubricant, O-ring removal tool
  • Sea Dragon EVA Case

For more information about Sealife Underwater Cameras visit the website by clicking here

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