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Aperture, Shutter Speed, and ISO for Underwater Photography



By Carlo Piscioneri, Founder of Night Sky Pix

When just starting out in low-light photography, trying to get your head around all the camera settings can be quite overwhelming. The purpose of this article is to get you up to speed with some of the most common terms related to camera settings, what they mean, and how they affect your images!

So whether you’re trying to shoot a starry night image, or into the cool depths of underwater photography, these principles will all apply equally.

Getting Started With Underwater Photography

If you’re planning on shooting underwater, getting to know your camera is extremely important. First off, to capture the best photos possible, you’ll need to set your camera to (M) Manual Mode.

Auto mode is great for daytime images, but in low-light situations where the conditions can constantly change, you’ll need manual mode and adjust your settings for the specific situation.

By doing this, you are taking control of your camera’s settings. Regardless if you are shooting underwater or above ground, this will make the biggest difference to your images.

Throughout the rest of this article, we’ll discuss the three Manual settings that all photographers need to look at when taking photos. They are aperture, shutter speed, and ISO.

Exposure Triangle

The term “exposure triangle”, is the combination of the three main components of photography.

Aperture, shutter speed, and ISO. All three work together to help bring out the best in your images and will determine the overall brightness of your pics.

Once you begin to understand how the three all relate to each other, you’ll have much more control of your camera’s abilities and settings, allowing you to adjust to the right settings for the right situation.

Below is a breakdown of each of these terms and what they do.


This is the first common term that you should learn in any form of photography.

Simply put, an aperture is the size of the opening in the lens.

Think of aperture as an adjustable widening and narrowing of the lens, the wider the opening, the more light will pass through and make its way to the sensor, while the smaller the lens opening the less light is allowed to pass through.

While there are many types of visual devices that use a reference of apertures, such as binoculars and telescopes, they lack something that digital cameras have, which is a diaphragm that allows you to adjust the amount of light that reaches the camera’s sensor.

Camera settings with the aperture wide open allow more light into the image, resulting in a brighter photo. This is of the utmost importance when shooting in low light situations like night and underwater photography.

The aperture is measured in f-stops, a small aperture like f/1.8 is a wide opening, a large aperture like f/22 is a very narrow one.

The aperture is one of three camera settings that determine the overall exposure and brightness of an image, (how bright or dark the final image is).

Depth Of Field

The aperture also affects how much of the image is in focus (DOF). Wide apertures result in a creamy, unfocused background, while narrow apertures keep more of the image in focus.

Choosing A Higher Or Lower Aperture Setting?

Depending on the final outcome you want to achieve from photographing a scene, here are a few things to consider.

When shooting an object close up, a wider aperture will make the scenery behind the subject out of focus/blurry. This is usually performed when shooting a subject close up, like a portrait photograph.

A smaller aperture setting will allow you to achieve a broader depth of field view so you can capture a broader area of focus. This is useful for landscape photography.

Shutter Speed

The shutter speed is the setting of the camera that opens and closes the shutter to let light in and take a picture. The shutter speed indicates how long the shutter remains open, written in seconds or fractions of a second, such as 1/200 s. or 1″, where the symbol ” is quite often used to denote a whole second.

If you reduce the time your camera’s eye is open by half (shutter speed), you then get half the ambient light in your image.

The longer the shutter remains open, the more light is let in. So why don’t we just leave the shutter speed setting as long as possible?

Because anything that moves when the shutter is open will be out of focus and blurred, and if the whole camera moves with the shutter open, the whole image will be blurred.

Does Shutter Speed Affect All The Brightness Of An Image?

Changing the shutter speed affects the ambient areas of your image. The faster the shutter speed, the darker these areas become.

What About A Flash Or Strobe?

The amount of light you get into the picture with a flash or strobe is not affected by the shutter speed, because a flash only flashes for a fraction of a second. Changing the shutter speed has no effect on how much stroboscopic light appears in your picture.


The ISO value determines how light-sensitive the camera is. For example, an ISO value of 100 means that the camera is not very sensitive – ideal for daylight shooting.

An ISO value of say, 3200 or more means that the camera will be very sensitive to light, so you can use this higher ISO value for low-light shooting. The downside to increasing your ISO value is that the higher the ISO value, the more noise you start to introduce into your images, resulting in a more “grainy artifacts” in the image.

While you still need to be careful when raising your ISO as to not introduce too much noise into your image, it’s not as much of an issue as it used to be.

Older models of DSLR cameras were notorious for introducing a lot of noise into a picture but nowadays, a lot of the newer model cameras, from Canon, Sony, Nikon, etc have much better camera sensors and can handle much higher ISO levels with minimal noise in an image.

Like all things, I recommend you test the threshold of your camera to see what you’re happy with when raising your ISO.

Lastly, when it comes to ISO, especially during any form of low-light photography, it is usually the last of the settings to change, as you really don’t want to introduce any more digital noise into your image than needed.


Low-light photography does take a little more effort than regular daylight photography. You’ll need to adjust a combination of the three components (exposure triangle), aperture, shutter speed and ISO to capture that perfect shot.

Hopefully this article has helped you get a bit more understanding of what those three do and why they’re so important.

To learn more about night photography, visit

Carlo Piscioneri

Carlo is editor in chief at You’ll often find him in the backyard testing out different equipment or techniques to try and improve his images. He loves to write about all things night photography and can’t wait to share what he has learned with you.

NightSkyPix is a site dedicated to astrophotography. When it comes to night photography, there are many, many options when it comes to equipment, configuration, and even what to shoot. Things can get complicated quickly, so the aim is to help simplify and teach readers by sharing great guides, tutorials, reviews, and resources.

Jeff Goodman is the Conservation editor and also the Underwater Videography Editor for Jeff is an award winning TV wildlife and underwater cameraman and film maker. With over 10,000 dives to his credit he has dived in many different environments around the world.


New academic study to confirm rehabilitative benefits of Scuba Diving



A new study into Scuba Diving Rehabilitation Charity Deptherapy’s approach to supporting Armed Forces veterans with psychological injuries such as Post-traumatic Stress Disorder (PTSD) through the medium of scuba diving has been carried out by Petra Walker in conjunction with Hanna Kampman of the Posttraumatic Growth Research Unit at the University of East London.

This study, which used Interpretive Phenomenological Analysis (IPA), demonstrates that scuba diving has rehabilitation benefits beyond those found in other forms of sporting rehabilitation exercise.

IPA is a qualitative methodology that examines the experiences of participants and has been used in previous studies of Posttraumatic Growth (PTG) in para-athletes.

Petra is an experienced diver herself and was exploring the wellbeing aspects of scuba diving as part of her Masters in Applied Positive Psychology and Coaching Psychology when she came across a previous study on Deptherapy. Past studies have mainly focused on the medical aspects of diving, so the opportunity to examine the mental health side of rehabilitative scuba diving was impossible to ignore.

The full study is currently embargoed until it is published at a future date in an academic journal, but it follows similar academic research into the work of Deptherapy by the University of Sheffield Medical School (2018) and the University of Nottingham (2019).

Richard Cullen, Chairman of Deptherapy commented: “This evidence-based study demonstrates yet again the value of scuba diving and, in particular, the support provided by Deptherapy to severely traumatised people within the Armed Forces community. We await the publication of the detailed findings which we anticipate will be of considerable interest to all organisations who seek to assist in the rehabilitation of veterans through sporting activity, as well as the Scuba Diving world.”

Team Deptherapy returned to the UK last week from their first training expedition since the start of the COVID-19 Pandemic. A small group of six veterans travelled with the Deptherapy Instructor Team to the charity’s international base at Roots Red Sea to undertake practical Scuba Diving training in the clear, warm waters of the Red Sea.

Joining Team Deptherapy for the first time was 20 year old paraplegic Corey Goodson who had this to say: “I have been made aware of a new academic study about the benefits of Deptherapy. Last week I learned to scuba dive properly with Deptherapy, a huge achievement for someone with paraplegia. Deptherapy doesn’t judge your injury, whether that be physical or psychological; it looks beyond, and it sees the person inside. That person is who they work with, and the Deptherapy programme encourages you to see your fellow beneficiaries in the same light. More important than the sense of achievement during the training, was the support, care, encouragement and love the team showed me. I have found a new family in Deptherapy. I am home now but the support, friendship and banter continue; it is motivating and empowering, it gives me a deep sense of wellness and worth. I look forward to continuing my rehabilitative journey with Deptherapy.”

For more information about the work of Deptherapy and Deptherapy Education visit

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Dive Training Blogs

Deptherapy returns to its Roots – Part 6



Join Richard Cullen from Deptherapy for part 6 of his Blog about the charity’s recent expedition to Roots Red Sea, El Quseir, Egypt.

Thursday has dawned and it is down to the House Reef with an outgoing tide that is approaching slack so we can get in the water straight away.   Lots of chat about last night’s RAID O2 Provider session with Moudi.  Oatsie is talking about sidemounts and marine biology, Swars is looking forward to his first sidemount session this afternoon.

Moudi is supported by Oatsie this morning and doing some more skill work with Keiron.

Moudi running the guys through the RAID O2 Administrator Course

Corey was asking last night about what it is like at 30 metres, so I have decided that with Michael and Swars we will take him to 30 metres.  We are going to run a narcosis exercise so out comes the slate with the numbers 1 – 25 randomly placed in squares.  Corey’s task, in the dive centre, is as quickly as possible to touch each number in sequence.  He does it pretty quickly and Michael briefs him that he will need to do the same exercise at 30 metres.

Michael briefs the dive and we set off down the beach.  Corey has improved beyond measure and he is becoming a pleasure to dive with.  So we are off to follow the South reef to 30 metres where we will complete the second part of the exercise.

At 30 metres Michael hands Corey the slate; there is a considerable difference in the time to complete the exercise at the surface and at 30 metres.  There are lots of mitigating factors in how quickly you can identify the numbers and explaining a slower time at 30 metres than at the surface does not mean an individual is suffering from narcosis.  Identifying random numbers, if you run the exercise at the surface, several times with an individual over a number of hours can result in wide variations in the time taken to complete the exercise.

We finish the dive with Corey smiling from ear to ear and we have a discussion about depth and air consumption.  The second dive of the morning is a fun dive, then it is lunch in the beach restaurant.  After the burgers I am sure we will need to look at our weighting before the afternoon’s dive.

We will need to look at weighting after this lunch!

Corey and Keiron have got into the habit of recording their dives online using the RAID online log book which is a tremendous facility and as the instructor I can access that data.

Moudi and Keiron are going for a fun dive as are Corey, Oatsie, Michael and myself. Swars is getting kitted up for the first experience of sidemount with Guy Henderson.

Swars getting to grips with his sidemount cylinders

People often look at the relationships that exist between the dive team and our beneficiaries and try to extrapolate a similar relationship to disabled students they might have.  Our relationships are built up over a period of time, in some cases over many years.  We also provide 24/7 support and have chat groups etc on social media; we also meet up socially when we can.  It is somewhat different than a individual coming in to a dive centre and saying ‘I want to dive’. Your relationship is likely to be the same as any other student, you will teach them, they might stay with the dive centre or like many that will go on holiday to do some diving, you might never see them again.

Our main aim is to create a family atmosphere for our programme members, one where they feel secure and they are able to discuss freely with the team and fellow beneficiaries their feelings and needs.

Few dive centres are charities, and owners might want to consider costs of running a course for someone with a disability that might take more than the standard four pool sessions etc.  You may find the number of sessions and the staffing levels have to increase.  Many dive centres, because of their size and turnover are exempt from providing accessibility.  How will this affect someone who is a wheelchair user?  Can they gain access to the dive centre, the classroom, the toilet?  What are the changing facilities, can they get wheelchair access to the pool?

Lots of things to think about.

Roots’ beautiful reef

The reef is beautiful, so much aquatic life and the corals look splendid, especially the pinnacles.

A good day’s diving, Swars has really enjoyed his sidemount.

Lovely way to relax in the evening with the Roots BBQ, a fitting end to a great day.

Last day tomorrow and our final blog!

Find out more about the work of Deptherapy and Deptherapy Education at

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