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  • An Avoidable Tragedy in Cozumel

    Mexico’s Caribbean island of Cozumel provides some startlingly good diving, which is often experienced by American divers since it is so conveniently close to the US. Diving tends to be organised in groups. It is not unusual for individual divers to turn up for dives.There are strong currents. This can lead to problems if one of the divers needs to return to the surface during a dive and that is what happened to a lady recently, with fatal consequences.

    The dive had not started well. It is reported that she had trouble with the inflator mechanism of her BC. Presumably, it tended to jam open or her own BC was not compatible with the regulator and direct-feed she had rented. So she disconnected it, intending to only connect the direct feed when she needed to put some air into her BC. This may be something that a well-practised regular diver can cope with but if anything else went wrong, it could lead to an incident pit.

    And something did go wrong. During the dive, she decided to abort and the dive guide went with her to the depth of a safety stop at, say, 5m deep. He had to be quick because on the current: He could easily lose contact with the rest of the group he was escorting. So he left her there, assuming she was competent enough to make it the short distance to the surface. He successfully rejoined his charges ar depth and continued the dive.

    We don't know what happened next. Her computer would not have recorded whether she actually made the surface or not, but her lifeless body was discovered by an entirely different group of divers some time later. It may well be that on achieving the surface, she forgot how to inflate her BC orally. She probably struggled to reconnect the direct-feed hose whilst finning furiously to stay at the surface. She might never ever have done that. She might have been carrying too much lead. She certainly did not drop her weights. Consequently, she eventually dropped and drowned. Drowning is never like it is portrayed in the movies. Struggling to keep afloat, she would have become exhausted and quietly slipped away. Nobody would have seen her go.

    What can we learn from this tragic series of events, a series of events that happens only too often with leisure divers? Firstly, never go diving unless your equipment is working one hundred percent efficiently. Secondly, be neutrally buoyant at all times. This means never wearing more lead than you need. If you think you need a lot of lead to go under, you are probably holding a large lungful of air. A properly weighted diver needs only to exhale fully to leave the surface.

    If you are neutrally buoyant, you will have no trouble swimming up to the surface, but wearing your tank and weights, you might need supplementary buoyancy to be able to stay afloat, breathing the atmosphere comfortably. This is when you need to inflate your BC and use it as a life preserver.  Know how to inflate your BC orally. That is why it has a corrugated hose. You do not need to use that hose to dump air (through the oral inflation valve) as many instructors still appear to teach. You have a dump valve positioned at the shoulder for that.

    If for some reason you cannot inflate your BC, you can still achieve flotation by dropping the lead weights you carry. I know that many worry about replacing integrated-weight pockets or a weightbelt after it has been dropped in this way, but it’s a small price to pay for your life, isn’t it?

    Think about it. Familiarize yourself with these actions. There is no reason to die in such foolish circumstances. And don’t expect anyone else to save you from your own folly. Don’t abdicate responsibility for your own well-being or even your life to a third person, someone you probably only met a short time before you went diving. Know how to work all your gear. Check that you know how to drop your weights and practise inflating your BC orally. Practice helps muscle memory so that it becomes second nature.

  • Disappointments of an Underwater Camera Salesman

    Ocean Leisure Cameras specializes in underwater photography equipment. We try to match products to each customer’s needs.

    Recently, a young lady came in to buy an underwater camera. She professed to be a professional writer intending to supply articles to diving magazines. She wanted a camera that was very straightforward to use.

    olympus_epl7_packageA friend had previously lent her an Olympus EPL7 camera in a housing so she naturally asked for that. It’s a system compact with interchangeable lenses that can be matched to suitable lens ports. The salesman (an award-winning underwater photographer himself) would have been happy to take her money but once he got into explaining to her the intricacies of using it, it became clear that she just wanted to get into the water, press a button and get usable pictures. She also blanched at the price, even though the EPL7 in an Olympus proprietary housing represented remarkably good value.

    So the sales assistant then suggested she might be happier with a more basic compact camera instead. She was with him for about five hours, during which time he told her virtually everything he knew about successful underwater photography.fantaseag9x_camera_package_1

    She ended up purchasing a Canon G9X in a Fantasea FG9X housing that gave access to all the camera functions and with the possibility to add additional wet lenses later, when she felt she could afford them. It was a good choice. He also sold her an underwater strobe (a Sea & Sea YS03) with which he explained how she could get perfectly exposed TTL strobe-lit pictures. It appeared to be the perfect solution and within her limited budget although she was advised to buy a wide-angle or fisheye wet lens if she could have afforded it. She couldn’t. Both the EPL7 and G9X outfits are becoming difficult to obtain since they are coming to the end of their production runs. We hope that something else as good value comes on to the market.

    ys03_package_idas_1The company was surprised only a few days later to get an email from the customer, by now in the Caribbean, accusing it of selling her equipment that was totally unsuitable for underwater photography. She stated that she was not sold the camera she asked for (the Olympus EPL7) and that it was not possible to adjust the white-balance with the Canon she had.

    The G9X can be set up to provide a one-button manual white-balance setting – something she had been demonstrated during the hours of consultation in the shop. It can also be used to shoot RAW files, which is the professional way of shooting since many settings such as white-balance, contrast (and even exposure to a degree) can be decided on long after getting out of the water. Not only that, but the feature, properly used, should take care of a lot of the contrast and colour decisions.

    Sadly, this is a case of someone neither managing their expectations nor bothering to read the manual!idas_uwl04_1

    Famous underwater photographers like David Doubilet must despair when they hear stories like this. The years that he has devoted to learning his craft are dismissed by a new generation who think they can simply buy an item of equipment and immediately become endowed with talent such as his.

    I got my first job with a diving magazine (the very same one she intended to provide material for) because I could reliably take pictures that were correctly exposed, in-focus and nicely lit – a skill that was quite rare in the days of wet-processed film. Today, digital photography with its instant feedback from the camera’s LCD display means that it is possible to learn (by your mistakes) incredibly quickly, but learn you must. I worked as an underwater photographer for more than two decades and although I never considered I was a master of the art, I got results that were frequently published. Even so, I used a camera outfit that cost ten times as much as the budget this young lady decided she had.

    I contacted the editor of the diving magazine that this particular young lady said to which she was intending to contribute her work. He told me she was a good writer but that he’d told her she needed to be able to support her writing with good photography. He told her to buy a camera.

    It was disappointing that the editor of a magazine could think that merely buying a camera makes someone into an underwater photographer! Have the standards of magazine publishing dropped so low?

    Magazines pay extremely poorly nowadays. Not many make a living supplying original material anymore. Most take pictures for their own pleasure and are knocked out if they see their work in print. If they can get a few hundred pounds in contributor’s payment as well, that’s a bonus. For this young woman to make any return on her investment in the most basic underwater photography kit will take a great many pages published.

    Most Ocean Leisure Cameras’ customers take pictures underwater purely for their own pleasure. Digital photography has made getting good results easier than it ever has been. However, it does demand a degree of dedication in that one should be totally familiar with your camera’s functions and operation long before entering the water. Don’t buy underwater photography kit on your way to the airport and expect to come back with masterpieces in light and shade. As is so often said, “RTFM!”

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    If you're really set on wanting to be a competent underwater photographer and don’t have the time or inclination to take up an apprenticeship with a master, give us a call and we’ll try and put you in touch with someone who runs underwater photography courses.

  • Ocean Leisure Does Not Sell Rebreathers

    There’s a good reason for this but it may come as a surprise when I was at the forefront of promoting this new way of diving as far back as 1993. In those days I had the privilege of using a prototype PRISM rebreather, taught under the auspices of its inventor Peter Readey. I wrote an article for Diver Magazine (UK) that was entitled “I have seen the future and it works”.

    However, the units we used had neoprene counter-lungs and we even dried out our scrubber material in the sun before repacking it, promising CO2 poisoning. How we were not killed was down to luck.

    The author with Peter Readey 1993 The author with Peter Readey in1993 (note the stylish wetsuit!)

    I experimented on terra firma with hypoxia by breathing from the unit with the O2 turned off. I wanted to know what the symptoms of oxygen starvation were. I discovered there were none. I simply went out like a light. If I was underwater I would have drowned but luckily I only suffered a severe headache for a day.

    Next, I was certified by Rob Palmer as TDI SCR diver No4 on the Dräger Atlantis, even though during the course one of the other trainees suffered a bad soda lime influx.

    My introduction to closed-circuit came courtesy of Martin Parker and Dave Thompson who had made some prototype rebreathers that were the forerunners of the Inspiration. Every time we surfaced, we joked it was amazing that we were still alive, we used so little gas. An article in Diver Magazine (UK) followed. I couldn’t wait to get to use a production model and within a couple of years, I found myself away in the Maldives with Martin with the very first units.

    Dave Thompson and Martin Parker with prototype Inspirations Dave Thompson and Martin Parker with prototype Inspirations.

    I was so excited about the performance possible that I wrote about this too in Diver Magazine (UK). We didn’t have any dive computers that were appropriate for closed-circuit diving so we introduced a bit of guesswork into the dives by setting the equivalent nitrox mix on our OC computers for the planned deepest part of the dive. One dive did not go as planned!

    I became certified as APD CCR Rebreather Diver No4. It seemed No4 was my lucky number. At that time, the duration of the Inspiration scrubber unit was thought to be to be 6.5 hours but the manufacturer had not considered how mean divers were and there was one notable death caused by running the same material for more than 10 hours. The manufacturer’s specification for the duration was soon changed to 3 hours to accommodate this phenomenon. That’s the duration at the CE test rate - 40RMV in 4°C. Later, the manufacturer introduced a temperature stick that gave an indication of scrubber efficacy. Nevertheless, divers still had to pack and manage their CO2 scrubbers efficiently.

    I then took an Inspiration on various diving trips and boat owners were very accommodating, allowing me to dive alone since CCR divers were few and very far between. The popularity of CCR seemed assured.

    It was in Cocos when I managed to do a dive and, being distracted by a whaleshark, failed to set my high set-point and could have seriously injured myself if I had not opted for in-water recompression (using the unit as an oxygen rebreather). Later, manufacturers introduced automatic set-point switching after they realised there were stupid people like me using them! Nowadays the calculations of deco computer built into the units take care of that sort of error too.

    The author with a Sentinel CCR (photo: Kevin Gurr) The author with a Sentinel CCR (photo: Kevin Gurr)

    However, during this earlier time there were some mysterious deaths by early adopters, all very experienced divers. Some had turned off their O2 supply in the shallows (to save gas?) not realising that the body needs a greater volume of oxygen as the ambient pressure decreases. Some were simply unexplained. I gained my own theory about these unexplained deaths when away in the Sea of Cortez with a closed-circuit PRISM. I found that it was possible to install the scrubber canister upside-down in the darkness of early morning and thereby by-passed it. I suffered a CO2 hit on the surface before diving but managed to still jump in the water, I was so confused. Recovered to the boat, I nearly suffered a heart attack but survived after a full day’s rest. It was devastating. If it had happened during the dive, I would have been credited with having had a heart attack. The scrubber canister was redesigned!

    The author and Dave Thompson with JJ rebreathers. The author and Dave Thompson with JJ rebreathers.

    I then went on to use the Sentinel rebreather under the watchful eye of its inventor Kevin Gurr, and the Scandinavian-made JJ Rebreather with Dave Thompson. Articles in Diver Magazine followed. Advances in oxygen cell technology and electronics had made oxygen level management a cinch. There were also adventures with the Evolution, a travel version of the Inspiration and Recreational versions of both Evolution and Inspiration that promised to take all the errors out of practical use. I then tried the user-friendly Poseidon Mk6 under the guidance of Jack Ingle. That company hoped to start a mass market for ordinary leisure divers. A vast number of divers have taken to rebreather diving.

    Technical divers began doing dives that were unheard of using traditional open-circuit scuba due to the amount of gas they would have needed to carry. However, obsessed with hypoxia as a danger, we had all overlooked hypercapnia or CO2 poisoning, another real killer. It had taken a back seat as a danger from the past.

    Familiarity can breed contempt. Confident divers were still coming to the surface with counter-lungs inflated as their unit attempted to give them more oxygen in the shallows than they needed at depth. This meant they could float comfortably without resort to their BC. If they closed the mouthpiece and breathed fresh air, I suppose there was no problem. However, many stayed breathing from the unit and if they turned off their O2 supply, as a prelude to getting out of the water, unconsciousness followed by loss of buoyancy as the mouthpiece fell from the mouth. It could occur almost within seconds, followed by drowning.

    Whether this was actually what happened or not, one could easily imagine the Sharkwater film director doing something similar before he dropped and died in the first days of February 2017. He had surfaced and given an OK signal when his buddy went unconscious. The boat crew, distracted with saving his buddy, took their eyes off Rob Stewart who was found drowned in the seabed directly below where they were, some days later. It was a tragedy.

    The author with a modern Inspiration The author with a modern Inspiration/Evolution CCR

    Modern CCR units have many convenient features built-in, unlike those early prototypes. However, there will always be the insidious dangers of hypoxia and hypercapnia, both unforgiving in a water environment. People often obsess with oxygen toxicity but subject to effective oxygen cells being employed, this rarely happens. Nor has any CCR manufacturer been successfully sued for making a faulty unit although one manufacturer found all its profits going to lawyer’s fees. Many CCR users have personally modified their units from the manufacturer’s specification and some have paid the ultimate price for that.

    Unlike conventional open-circuit diving, rebreathers leave little room for mistakes. The fact I got away with it in the early days, I put down to luck and nothing more. In the meantime, Ocean Leisure prefers not to supply such equipment. It’s not for every diver.

  • The Dangers of Social Media

    Occasionally, a boat crew witnesses some diver doing so incredibly stupid that, rather than dismiss it as a one-off event, it’s simpler to write it into the boat’s policy or procedures. Like the liveaboard I worked on once; we had a rule that divers, equipped with tanks in place, should step down the ladder at the side of the hull and step backwards into the inflatable pick-up boat.

    That was because someone once decided to come down the ladder with his back to it and fell off into the boat, injuring those he fell on!

    My mother-in-law is not young and she has become a very cautious diver. My wife, her daughter, gets very impatient with her at times. She says she has lost her driving confidence but maybe it’s because she’s simply seen too many bad things happen.

    We are daily regaled with video clips of people bravely doing hazardous things on social media. At the same time we see for example, car ads and motoring programs on television shows where cars are being driven very much unlike the way my mother-in-law drives. Despite mandatory warnings about doing the same however, they might persuade young drivers to try to emulate them.

    Like driving, scuba diving is not seen as a spectator sport. Divers actively participate. This can lead some people to think they can do the same as the divers they admire, which often is not realistic.

    As a journalist, I have done many dives in my past where I was a sort of pioneer. Not many had dived the Thistlegorm in the Red Sea, the Saratoga in Bikini Atoll or the Bianca C in Grenada when I first dived and wrote about them. I was one of the first (with Jeremy Stafford-Deitsch) to dive with the bull sharks in Walkers Cay and more recently I was one of the first to photograph Great hammerheads in Bimini. In every case I was followed by endless numbers of divers, who seeing my articles in magazine, quite naturally thought, “I want to go there too!”

    And why not?

    I was in at the beginning with close-circuit rebreathers, diving several prototypes, and I gave them massive positive publicity -- only to later feel really guilty when some very highly-thought-of divers paid the ultimate price of insufficient knowledge. (I had been lucky.)

    Today we have social media in the form of Facebook, Youtube and Instagram, where we can instantly post pictures of what we are doing for the delectation of others. People take little POV cameras on dives and all is revealed almost the instant they surface.

    When divers hear about a really cool new bit of kit, a new all-singing-and-dancing computer or they see a really exciting dive site, they naturally want to have the same. It’s very seductive.

    There might be hidden snags. It’s like looking at a beautiful West African beach in a photograph. You can’t see the amoebic dysentery!

    The diving video of the wall dive looks cool but you cannot see the massive down current. The inside of the cave is stunningly beautiful, but you cannot see that it’s a long swim back out to daylight and a clear surface.

    Some divers are probably less than competent to be in the water. Some are sublime professionals with everything under control – like Exley, Palmer, Parker, Shaw, Bennett and Molchanova. Like them, they got it right many times over but they only needed to get it wrong once.

    Take someone out of a familiar environment and it can go wrong. A hugely experienced diver in the tropical Philippines might experience great difficulty confronted with diving in a cold lake wearing a drysuit.

    Someone who’s often dived in caves with still water might get freaked out in the strong flow of water diving in a tidal Bahamas Blue Hole.

    Some of us have done thousands of dives. I had up until a few years ago when I was diving intensely, but I’m out of practise now. I’m also older and a lot less fit. On the other hand, the golden years now that the kids have left home, are usually an opportunity to do those things we always wanted to do. Elderly men buy that motorbike they always wanted and find themselves sitting astride a space rocket they can no longer handle. Elderly divers might splash out on the DPV they always wanted or or a rebreather. We are tempted to buy all that stuff we previously denied ourselves.

    The question is, are we still fit enough? Are we dived-up enough? Only you can answer that!

    Most of the readers of this blog will be holiday divers. We might make several trips to dive each year. By the end of a dive trip, we’ve got quite good again, but I bet there were a few snags each time at the beginning.

    The majority of Ocean Leisure readers will be intelligent enough to know not to push themselves beyond perceived limits but I bet you’ve witnessed a few other divers doing what might be crazy things. How can that be? I blame it on peer pressure but whereas peer pressure was once confined to the people you met face-to-face, social media allows you to be ’friends’ with some of the biggest names in diving.

    This allows some divers to be misled into thinking they can do the same sort of diving. It’s easy. It rarely goes wrong in the memory card of the POV camera. They should remember that few keep a visual record of their foul-ups.

    You never get to see the called dives and near misses, the dives that went really wrong. Few are self-deprecating on their social media posts because so many of the very experienced divers are also touting for business, selling course and instruction.

    It’s not a question of loss of confidence. It’s about being cautious. It’s about coming back to tell the tale. So stay safe. Don’t encourage others to undertake dives that might be too difficult or too daunting for them. And keep an eye on those that might have a bigger ambition than competence. Scuba diving is real life. It’s not a social media experience.

  • Video the Light Fantastic

    Lighting for underwater videography has never been higher performing nor such good value as it is today thanks to battery technology that can pack a lot of power into a small space resulting in good burn-times per charge and the ability to fire up high output light sources. At the same time LED technology has progressed to make the most of this.

    bigblue_dualsetupNowadays you can get a nice useful set-up for use with a GoPro for as little as £400 including the tray and mounting arms. That’s two 1000 lumen lights with wide evenly lit beams.

    A word about lumens. Every manufacturer rates their light by the lumens they output. However, a 1000 lumen light with a narrow parabolic reflector will punch its way through the water so that more light arrives at the subject. This light is measured in LUX. Alas, video demands even lighting. Otherwise you’ll get a very patchy result. The more lumens you start with the better you results will be.

    You can get lights that accomplish the same output in lumens but in different ways. Some use a cluster of small LEDs while the better ones use a single large LED. Why do I say ‘better’? Well, it’s about the quality of the light. A cluster of LEDs will provide a cluster of shadows when close to the subject and although this might not offend the eye when looking directly, it can tend to give the image a degraded unsharp appearance.idas_venom38_1

    So what if you set the light further from the subject? You’ll appreciate that nothing is brighter than the sun yet the colour of its light is degraded once it has passed through only a few metres of water. That‘s because water absorbs light selectively. The longer wavelengths from the spectrum, the reds and greens are quickly soaked up by the water, leaving only the blue light to penetrate very far. That’s why unlit video looks blue once you get very far from the surface.

    The same thing happens with a video light. You’ll notice that as you get closer to your subject with your camera and lights, the subject does not simply become brighter, it becomes more colourful. Even the most powerful video light has a problem penetrating much more than a metre of water, once it is competing with daylight filtered blue from the water above. Strangely enough, it’s in daylight that you need more lumens and it’s for this very reason.

    At night or inside a dark wreck or cave you’ll find the less powerful lamps are just as effective. It takes a very bright light indeed to light up a reef in daylight and you will still need to get as close as possible and use a fisheye lens to restore the full width of subject.

    bigblue_big_2So my advice is to get the lights with the greatest output possible from a single LED with a wide beam reflector. Why do I speak in plural? Well, with video you need an even light  over the subject so two lamps of half the output in lumens will be superior in effect to one lamp of twice that.

    There’s then the question of the colour of the light. This used to be described in °Kelvin. The higher the temperature the more blue the light. Daylight on a sunny day with puffy white clouds is around 5500°K so that’s a good light source colour temperature to aim for. There’s also the Ra rating. The manufacturers of more sophisticated light will provide this in their specifications. This reflects the color rendering index of a light source and determines the spectrum of the light produced. Like fluorescent tubes, some LEDs are missing part of the full spectrum and thereby give some less than satisfactory colour rendering, depending on the colour of the subject matter. However, since what you will be recording is underwater and rarely seen by natural light, who’s to judge what’s right?rbblue_system2_light_1

    A word about flying with lithium batteries: To determine whether you can carry your lithium batteries on board a plane requires your close inspection of the batteries. It depends on their configuration and either Watt/Hour (Wh) rating for rechargeable batteries or Lithium Content (LC) for non-rechargeable batteries. To convert Amp/hours (Ah) to Wh, multiply the marked Ah rating by the rated voltage of the battery. (There are 1000 mAh in 1 Ah.)

    Less than 100Wh or 2G (LC) batteries contained in equipment can be carried on or stowed in your checked baggage. Typically, the AA batteries commonly used in much photographic equipment fall into this category. However, you must carry spare batteries with you, not checked in.

    Laptops usually have 11.1v batteries while mobile phones use 3.7v. More than 100Wh but less than 160 Wh batteries can be carried on or checked if installed within a laptop, camera or mobile phone, but you must carry on your spares (a maximum of two). However, you should get operator approval for the spares from check-in staff. If you have a video or powerful dive light, check the size of the batteries if they are lithium. They will be marked with Ah/voltage or Wh. Batteries of more than 160 Wh can only be presented to check-in staff and packed in your checked luggage in accordance with IATA Dangerous Goods Regulations. Generally, large lithium battery packs such as used in DPVs are barred from air transport. If you want to transport such a DPV by air, check that its battery pack is ni-cad.

    fisheye_fixneo_batteryIf you carry on spare batteries, their terminals must be protected from short-circuiting by either enclosing them in their original packaging, taping over the terminals, or carrying each battery in a separate plastic bag. Batteries in the mobile phones, laptops, etc., that you check must be switched off and measures taken, if necessary, to ensure they cannot be accidentally activated. More info: www.iata.org/whatwedo/cargo/dgr/Pages/index.aspx

  • Take Lots of Water With It!

    It’s no secret that our bodies depend on water for survival. In fact, it could be said that half our body weight is water. Every cell in our bodies depends on water to function properly. As a general rule, men need around 3 to 4 litres of water per day while women need slightly less. So what’s this got to do with water sports?

    We lose water through sweating and evaporation of that sweat accelerated by a sea breeze or the greater flow of air felt during a fast motorboat ride. Sweating underneath an exposure suit can be profuse but because it might not be noticed its effects can be insidious.

    Naturally, our bodies lose a lot of water simply through respiration. You can see the water vapour on your breath on a cold winter’s morning, but the water is there even when you cannot see it precipitating as vapour.

    We tend to enjoy water sports most where the weather is warm and sunny. Getting sun burnt can cause the body to rush fluid to the site of any irritation so reddened skin will mean you need to imbibe more water than otherwise.

    Most of our activities, be it sailing, surfing, water skiing or scuba diving, take place in seawater. Sea spray can leave a residue of salt water that turns to crystals as it dries. Since salt is hygroscopic it has the ability to attract and hold water molecules. When it sits on our skin it can pull water away from the skin tissue, where it quickly evaporates.

    If you scuba dive you are particularly susceptible to dehydration because you breathe air (or nitrox) that has been dried before it was pressurized to fill the scuba tank.

    Then there’s immersion diuresis, the technical term for peeing while you are underwater. As we dive, ambient water pressure and the cooler temperature of water may both have a role in shunting blood from the extremities (arms and legs) into the thorax.  When the body recognizes the increase of blood around core organs, and the subsequent increase in blood pressure, it attempts to flush fluids by increasing urine output.  That is the reason for the frequent need to urinate during dives.

    Hopefully, you don’t suffer from seasickness but if you do be aware that vomiting has a dramatic effect by leaving you severely dehydrated along with a severe electrolyte imbalance.

    It is also very important to recognise that drinking alcoholic beverages, though quite common during dive vacations, can cause dehydration. Alcohol consumption actually counters water consumption since it is a diuretic. Alcohol diuresis results in increased urine output. The alcohol suppresses production of the body’s anti-diuretic hormone leaving the person with a frequent need to urinate, speeding up the loss of fluid from the body, and leading to dehydration.

    Dehydration is especially important to avoid if you are scuba diving because it has been proved time and time again to have a link to decompression illness. Being dehydrated increased the possibility of a diver needing emergency treatment for the bends. Even if you are not a scuba diver, it can lead to discomfort and loss of performance leading to mistakes being made.

    So how do you know if you are in danger of being dehydrated? You may produce reduced amounts of urine than normal and it may look darker than usual. A headache is a sure sign. Of course you might experience a severe thirst, with fatigue or even sleepiness. Feeling dizzy or light-headed is a warning sign as is confusion and the inability to concentrate.

    As the blood thickens to reduced water content, the circulatory system becomes compromised. It’s ability to transport nutrients and blood gases such as oxygen, carbon dioxide and nitrogen diminish.  This leads to muscle fatigue, cramping, high blood pressure, rapid heartbeat, confusion, and increased breathing.

    Mild to moderate dehydration can lead to weakness and exhaustion, muscle cramps, poor air consumption (by a diver) reduced awareness and for a diver, an increased risk of decompression illness.

    So hydrate early and at regular intervals, gauge your consumption by carrying a marked bottle. Eat plenty of fruit because not only does it contain water, it has fructose and vitamins too.

    Use the shade as much as you can and wear your exposure suit only when you are ready to use it in earnest. Apply plenty of sunscreen and know that even waterproof sunscreen gets washed off. Rinse dried seawater off as soon as you can and wear a brimmed hat and a long-sleeved shirt.

    Avoid diuretics like alcohol if you are going to scuba dive. Drink plenty of plain water!

  • The Diving Equipment Manufacturer’s Association Show in America 2016

    DEMA Report. The American annual diving trade show was held during mid-November. While in past years the event has appeared to shrink in size, I am happy to report that the leisure diving industry looks to be recovering and the show at the Las Vegas Convention Centre seemed much larger and more vibrant than in recent years. Every aspect of diving was catered for and there were many interesting new products as well as some very quirky ones exhibited. Here’s a selection. Take your pick!

    Swes Technology Dive Light. Probably the most portentous product in the DEMA show, the European-made SDL-600 dive light has no battery but is powered by seawater! Its patented energy cell using graphite and magnesium rods is said to last for 2190 hours and the lamp itself is rated to 100m deep. Electrolysis powers the 1pc CREE XM-L2 U2 producing a maximum of 1140 lumens. www.swesholdings.com

    Aqua Lung Outlaw BC, the brainchild of Aqua Lung’s Don Rockwell, is completely modular, allowing the buyer to tailor a perfect fit. It’s four main parts include a choice of two different buoyancy cells, different length shoulder straps, and waistband, all of which easily snap together. One can attach different size integrated weight pockets and the whole can be conveniently transported broken down into its constituent parts. With soft D-rings and a daisy chain loop feature for multiple ways to attach gear, it weighs only 1.8kg. I could imagine this might prove extremely popular with the travelling diver. www.aqualung.com

    Easy Dive Nomad combines a snorkel with a compressed air cylinder that can easily be switched to when the user is underwater. But it seems as if a snorkeler might too easily hold a breath taken at depth and then ascend unwittingly with a great chance of inducing an air embolism. This hazardous item, complete with Spare Air cylinder, is unlikely to be available at Ocean Leisure. www.easydive.us

    ProShot Case. Among numerous offerings of underwater housings for iPhone 6/6S and iPhone 7 at DEMA, this one interfaces with the majority of GoPro mounting accessories and for less than £100 includes a wide-angle lens. Another £50 will get you a 151° fisheye lens to increase the angle-of-view of your iPhone camera. www.proshotcase.com

    Paralenz Dive Camera. With a target price of just $599 in the USA, this precision little Danish unit starts recording as soon as it goes underwater. Watertight to 200m, it uses clever programming to adjust the white balance for color-corrected pictures according to depth. But it’s more than just a camera. The Paralenz app generates a time, temperature and depth graph linked to the recordings (either still pictures or live action) and this information can be embedded as an overlay. Combined with an iPhone, footage is shared at the click of a button and its rechargeable battery is said to be good for more than two hours use. More than 200 divers in 35 different countries have tested it. www.paralenz.com

    Buddy Watcher. Using ultrasound frequencies, this is wrist mounted unit can draw the attention of another diver, or even a group of divers if so equipped, by vibrating and flashing an LED. Its calling-distance is 80m and it represents a discreet method of keeping divers in touch with each other – provided they can see each other! www.divealert.com

    Nautilus XP and GLH. This is a tank-mounted propulsion system for divers that weighs less than 7kg and is only 43cm in length. The two small propellers of the GLH deliver 5.4kg of thrust each, enough to propel a diver for up to 40 minutes and its remote control can allow a diver to reverse out of tight spots too. The XP has a single propeller. An on-board depth-sensor will maintain a diver’s depth. Two separate battery packs are said to be a legal configuration within current airline rules. www.indigo-industries.com

    Indigo Fins. When it comes to fins, every DEMA has a hopeful company attempting to ‘build a better mousetrap’. This year, Indigo Industries exhibited a range of fins, Apex XT, Shift XT and Defiant XT, with zip-on alternative blades, both split and paddle, and variable stiffeners plus foot pockets for either boots or bare feet. Ocean Leisure customers want fins they can fit and forget. We can’t see these taking off in the UK. www.indigo-industries.com

    Polar Pro demonstrated a new submersible lighting rig for GoPro, the Triton LED Dive Tray, that includes a tray and two grips that are each equipped with a 500 lumen  video light and with batteries built in. We are hoping to have them soon in stock and they will probably sell for less than £200 each. www.polarprofilters.com

    Atomic Aquatics BC. For delivery later next year, the company known for the highest quality products regardless of cost has come up with its first and what is promises to be the most expensive-to-buy BC yet. Of a conventional jacket type, it uses an absolutely watertight material that gains no weight when wet, it has a novel camband that promises to keep a tank forever secure and it has large pockets with covered zips. I doubt if you’ll any of these stocked at Ocean Leisure. It’ll be to special order only. It might last a lifetime but at around £1400 it needs to! www.atomicaquatics.com

    iBubble Camera Drone. This is an autonomous underwater drone from France that promises to follow you on a dive and record the ultimate underwater selfie. It’s wireless, rated to 200 feet (60m) deep, and has two 100 lumen lights. It automatically avoids underwater obstacles, has image stabilization, a one-hour battery life and automatically returns to the diver who wears the control bracelet when it is out of battery life. It costs around £2000 and is available for pre-order for investors on Indiegogo, with delivery expected in September 2017. www.ibubble.camera

    Voice-in-the-Sea Narrator. If you want to add a commentary to your underwater GoPro footage at the time of shooting, the Narrator is a tube-like device that allows you to record, with a tinny Great War U-boat speaking-tube quality, directly to the microphone of the camera. It is expected to sell in the USA for around $40 but I doubt you’ll see any sold this side of the Atlantic. Available for pre-order. www.voiceinthesea.com

  • Basic Rules for Underwater Photography

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    Some Basic Rules for Underwater Photography

    Make sure your camera is protected from the water, in a submarine housing, if it is not an amphibious camera like an Olympus TG4.

    Get Close - Then Get Closer Still!

    Water also upsets the sharpness of your pictures because it is never optically clear. Reduce the amount of water between you and what you are photographing to a minimum by getting as close as you can. This means using a wide-angle or fish-eye lens or an extreme close-up macro lens for sharper clearer pictures.

    Water absorbs light selectively. Red light is absorbed first, followed by green and then blue light. This means, the deeper you are the more the daylight is filtered blue by the water.

    You can counteract this in different ways.

    • Stay very shallow.
    • Stay shallow and use a filter to remove the excess blue light.
    • Adjust the colour sensitivity of your camera’s sensor by ‘white-balancing’ subject to there being enough red light penetrating to the depth you are at.
    • Take some independent white light of your own.

    Portable white light comes in two forms:

    Video Lights provide a continuous light source. The brightest video lights can also be used for close-up still photography. They have the advantage that you can see immediately the effect they produce. They have to produce a perfectly even daylight-colour light and their output is rated in LUX.

    Electronic Flash (called strobe in America) can produce a far greater amount of light but only in a very short burst. This has the advantage of freezing the action for very sharp pictures but it takes practice to anticipate the effect. You need to synchronise the flas so that it can be triggered by the on-board flash of your camera but at the same time you need to be sure that light from the on-board flash does not leak out and spoil your pictures.

    Backscatter occurs when the detritus in the water in front of your camera is lit up by either your video light or flash. To avoid that, position your light a long way from the optical axis of your camera lens. The most convenient way to do this is to mount it on an arm that is fitted to your camera tray. The wider the angle-of-view of your lens, the further the light should be from the lens or the longer the arm needs to be. Avoid positioning a light ahead of a wide-angle lens.

    Balance the foreground light that will be in full colour with the background lighting to obtain a natural effect. The shutter speed only affects the constant light whereas the f/stop setting and ISO setting affect the overall exposure. Don’t be afraid to practise. Shoot RAW files that can be adjusted in your home computer afterwards.

  • Twenty Ways to Improve Your Diving

    Most Ocean Leisure customers are experienced divers who don’t need help improving their technique, but at the risk of teaching our grandmothers to suck eggs, here are a few suggestions and, who knows? You might spot a useful nugget among them!

    Get Your Trim Right. Often, divers carry the right amount of weight but in the wrong place. Consider where the fulcrum or pivoting point of your body will be. Integrated weight pockets on a BC might be too high up on a long-legged diver. A weight harness allows weights to be slung lower. On the other hand, a diver wearing a lightweight suit and using an aluminum tank might need to add some weight higher up and, if the BC in use has no trim-weight pockets, you can always add a couple of kilos to the camband that goes round the tank. You need to be comfortably horizontal in the water without any tendency to invert.

    Deploy a Marker Buoy Easily in Mid-water. Why do so many divers make a mess of this? Is it because they haven’t been shown how to do it? If you carry a big camera, learn how to do it easily with one free hand. Buoyancy changers appear to be the main enemy of a slick deployment. Using exhaled air to inflate the buoy avoids this because the buoyant air is simply moved from one location to another. Stream the buoy so that it floats above you. A tiny bit of exhaled air in it will help keep it up. Pull off as many metres of line that is practical, so that your reel hangs below you. Take the open end of the buoy and hold it with fingers and thumb above the upper side of the exhaust-T of your regulator while holding your head a little to one side. Have the line passing through but not gripped by your hand. Exhale into the buoy. It will start to ascend. Inhale again immediately releasing your grip on the buoy and grab the reel as it gets pulled up to your hand. Release the line from the ratchet of the reel. Watch the buoy go. Tighten off the ratchet, taking up the tension on the line, as soon as the line becomes slack because the buoy will have reached the surface.

    Carry a Flag. It was recently reported that Australian diver Jacob Childs spent a worrying afternoon alone, drifting at sea, before he was picked up. Childs had an inflated surface marker buoy, which is good for being spotted over a short distance but less good when in more dire circumstances. High-tech electronic solutions need to be kept fully charged and you don’t know if they are going to work until you need them. A low-tech solution is a big flag at the end of a long pole. Three lengths of plastic tubing that fit one to another and a length of elastic bungee running through the middle snap instantly together to form a tall pole with a large yellow flag at the top. When not in use it’s carried strapped under a couple of elastic straps round your tank. If you’ve dived in many remote places, most of which enjoy powerful currents and you’ve used it in earnest you’ll appreciate its efficacy. It’s low-tech, it’s cheap to buy, it can be deployed single-handed, and once used you wouldn’t go diving without it.

    Get Your Weight Right. The human body is more or less neutrally buoyant. Take a big breath and you float. Empty your lungs and your heavy head will go under. If we didn’t wear buoyant kit such as our suits, we wouldn’t need to wear weights. If you want to get your weight right, exhale hard at the surface and the weight of your head in the air should push you down. Add an extra amount of lead to compensate for the weight of the gas you might exhale out into the water during the dive and you’re perfectly weighted. So why do so many divers wear too much weight? Is it because they are used to plummeting to the seabed and trampling around before putting air into their BCD to make it back to the surface? Neutral buoyancy is the very essence of pleasurable diving.

    Long-Hose Your Octopus. The alternate air source you carry is not for you. It’s for use by another diver, in the event of his or her own gas supply being unavailable. Rigging your alternate air-source (octopus rig) on the left side of your body will ensure it’s the right way up and easy to use by another. It takes the drama out of air-sharing. Better still, employ a long hose of about a yard and a half or more so that they can use it without any drama for either of you. You can rig this long hose in a number of ways. It will be easy to stash under an elastic strap or two round your tank, as long as you can access it easily. Some advocate passing it under the right arm, tucked under a waistband, passing it up across the chest and round the back of the neck so that it becomes the primary regulator. They then pass this over if need be and go for an alternate second stage rigged where they know where to find it easily. Whichever way you rig it, make sure it’s visible and works properly at the beginning of every dive so that you’ll know it will work should it be needed in a hurry.

    Use a Regulator Necklace. Putting your regulator on a necklace arrangement is a good idea if diving in low visibility. If the hose gets snagged on something as you pass or a buddy accidentally hooks it out of your mouth, it won’t be going very far and you can soon replace it. A necklace is a good idea for your own alternate air-source if you are using a primary regulator on the end of a long hose as your primary regulator and likely to need to donate it. You can buy a purpose-designed necklace from your local dive store or make one yourself from surgical rubber tubing.

    Take Enough Gas. It’s obvious that for the same amount of work, a bigger diver will use more gas than someone smaller. It is also obvious that a bigger diver will be able to handle bigger tanks. If you are working to get good pictures, you’ll use a lot more gas than if you are just hanging about feeling slightly bored. Don’t battle to keep your gas consumption within the same range as someone else. Start off with sufficient gas to do the dive. This might mean requesting a bigger cylinder or even twinning up a pair of what’s available, using, for example,  twinning blocks and bands.

    Use a Current Hook or Reef Hook.  It’s a fact of life that big fishes are attracted to current points. That is to say, the places where the flow of water has to speed up to get up or around an obstruction such as a reef or wreck. It can be fierce. Some of the most notable places for observing this phenomenon are also known for the absence of any living coral on the reef top due to the fact that so many divers have clung on there. A current hook, so deployed that it attaches only to substrate or a handy rock, enables the diver to anchor in place while making himself slightly positively buoyant in such a way that he flies above the coral reef rather than ruining it by lying on it or colliding with it. What is a current hook? It’s an open-ended hook that can hold at its point, attached to some sturdy line or narrow gauge webbing that is clipped to a convenient D-ring on the diver’s BCD. Some local dive guides don’t allow the use of these hooks because they don’t trust their divers to use them responsibly.

    Wear a Suit That Fits Properly. If your drysuit fits your perfectly, there will be less of a drag when you are swimming. If your wetsuit or semi-dry is too big, cold water will flush around it under the arms and around the groin so that you’ll soon feel cold. If your drysuit is too small you either won’t be able to sit down in it or you’ll be limited to the choice of the undergarment you can wear with it. If your wetsuit or semi-dry is too small, it might interfere with your ability to breathe. If you can’t find the right size off-the-peg, get one made-to-measure. In the case of a drysuit, it might mean visiting the manufacturer a couple of times in order to get it right.

    Be Well Hydrated. Being well hydrated is not just a matter of drinking lots of water. In tropical countries the fresh water supplied in plastic bottles is often produced from seawater by reverse osmosis. This makes it pure but pure isn’t good enough. We need minerals in our water supply to get benefit from it, so make a point of adding a rehydrant powder or effervescent tablet to the designated amount of water so that it forms an electrolytic drink, at least once per day when away somewhere hot. Beer is a good rehydrant because it is mostly water and contains plenty of minerals but the alcohol contained within it suppresses the production of anti-diuretic hormones and you’ll just simply pass it through -- not to mention the brain damage that it gives you too. So the first beer of the day signals that you’ve enjoyed your last dive.

    Get Spring Straps. The single most important thing that can improve a pair of fins is the substitution of a pair of stainless-steel spring straps or elastic bungee straps for the rubber straps they were supplied with. It’s not just the fact that you avoid that embarrassing moment when a rubber strap breaks as you pull your fins on and you don’t have a spare with you. Spring straps enable you to pull the fins on and off in a moment and they contrive to hold your foot firmly in the foot-pocket of the fin. There’s no wobble and all your effort goes towards propelling yourself forwards. Stainless-steel spring straps are available for every fin that has an open heel.

    Entering the Water With a Camera. You’ve prepared your underwater camera housing by gently greasing the O-rings and making sure their grooves are free from detritus, but you still feel insecure about jumping in with it. Boat crews can be helpful, but they are not camera experts and they may mishandle it. You may be required to do a negative entry because of the current. Under those circumstances, coming back after jumping in for the camera to be passed down by a crewmember might well result in your missing the dive site entirely. Whether you’ve spent a few hundred dollars or more than $7000 on a camera outfit you’ll be just as circumspect when it comes to getting into the water with it. The best trick is to hold the camera in your hand, dip it into the water and, without letting go of it, follow it into the ocean. This works whether you’re on the swim platform of a big boat or doing a backward roll from an inflatable. It may not look elegant but it works.

    Hang About and Look. There’s a new kind of diver around, rather in the same way as there is a popular style of skier. In the Alps they call it ‘en-piste’. Many divers get in the water and spend all their time swimming to catch up with the diver in front. They don’t see what’s down there. They simply complete the dive. It’s rather like a skier coming down a blue run and never taking time to examine that breathtaking view. Take you time. Have a good look at what’s there to see. Get yourself a compact digital camera. They are easy to use, offer a high success rate with macro subjects, will give you an interest in the smaller animals, and you’ll come back with a lasting memento of every dive. If the dive-guide swims onwards, they’ll soon be back to find you, especially if they want to keep their job. Often. It’s the smallest things that make a dive interesting and it’s shame to be down there, swimming on endlessly in the blue without seeing it.

    Stalk the Wildlife, Don’t Chase It! Everyone seems to have an underwater camera now, but they behave very differently with it underwater than they would if they were on safari on land. Why? Do they think they are invisible? If you see a dramatic pelagic animal, don’t chase it. You won’t get a close-up picture that way and you’ll simply drive it away from everyone else. It has seen you coming and even Michael Phelps wouldn’t be able to overhaul it. Instead, avoid looking directly at it. Marine life is tuned to be threatened by the eyes of predators. Swim to where you think it might be going. Take into account what other divers who might have seen it might be doing. They can be employed as unsuspecting beaters. ‘Head it off at the pass’. The only way you’ll get close to it is if it swims up to you. Turn yourself into an ambush predator. As old-time jungle hunters used to say, “Slowly, slowly catchee monkey.”

    Learn to Line-lay. If you penetrate a wreck or other overhead environment, you should lay line. The late Rob Palmer, doyen or early technical divers, used to say that line laying was an art. If you enter a wreck or cavern and are intent on finding your way out, it’s a good idea to copy Theseus with his ball of string. In the Greek legend, he found his way out of the Labyrinth after slaying the Minotaur. Lay it on the way in and follow it on the way out. The problem comes when the water moves -- and wrecks and caverns offer more hazards than any Greek mythological hero encountered. You can inadvertently pull a line into a place that it will snag and will not allow you to follow it back, or some other diver can inadvertently do that for you simply by the downwash of his fins. Belay the line as you go, tying it off at various convenient points so that this can’t happen.

    Get Your Kit Off Easily. When you get picked up by someone in a boat, there’s a good chance you’ll be close to what might well be a boat hazard, such as a reef with breaking waves. The wind might well be pushing the boat that way. It’s imperative that you can pass up your weights and any loose items you might be carrying, and get out of your gear in a timely manner. Inflate your BCD so that nothing will sink beyond reach. With your regulator still in your mouth and your mask and fins still in place, unclip the sternum strap and waist strap and one buckle at the shoulder. You can now swing the whole thing off your right shoulder while still holding on to the grab line of the boat with one hand. Push up from underneath to help the boatman avoid a hernia. If you have a one-piece harness with no shoulder buckle, the best thing to do it to pull it over your head. Actually, what happens is that you duck underneath it as its weight pushes you down. Keep your mask in place until you are safely in the boat. So often the mask is one of the first things that gets passed up. It makes the diver vulnerable because they can’t see what’s going on underwater and the mask vulnerable to getting broken in the bottom of the boat too.

    Learn How to Access a RIB or any Inflatable. Why is it that some younger people cannot climb easily in and over the inflatable tubes (sponsons) of a RIB from the water yet most old-age pensioners can? It’s because nobody has shown them how to do it? It’s not about strength. It’s about technique and knowledge. First choose the tube on the side where everyone is sitting. The other tube will be higher out of the water. Once you’ve passed up all your gear save your mask and fins, take hold of the grab rope (they are properly called ‘beckets’) with your hands about equal to the line of your shoulders. Take a breath and push vertically downwards as hard and fast as you can. You’ll momentarily fight your buoyancy, which will send you rushing back upwards. Fin hard at the same time to get as much upward velocity as you can. Straighten your arms, locking out, and tilt your head and chest forwards over the boat tube so that you tilt into the boat. Bring a knee up onto the tube. You’re there. Get someone to help you off with that first fin if need be before bringing the other leg inboard.

    Wear a Hood. Some people think that wearing a hood is done to keep a diver’s head warm. Well that is obviously the case and although medical men might argue about how much heat is lost through the head, your brain has an exceedingly good supply of blood and there’s precious little fat on most people’s head to insulate that from the cold water. There are other reason’s to wear a hood too, and that includes when in tropical waters. Tropical waters are rich in zooplankton and much of it carries nematocysts or stinging cells. The less skin you leave exposed the less chance you’ll have of suffering an irritating sting. Gentlemen who sport a moustache and leave plenty of stubble in place on their faces find it protects from the man-eating zooplankton too. Ladies might not have that option. Another reason for wearing a hood? When you are at the surface there’s a lot of ultra-violet light on your head and it’s reflected from the water. A hood keeps you from getting sunburned.

    How to Wear Wetsuit Boots. Why do you wear socks with your shoes? You’d probably get blisters otherwise. Many experienced divers wear a pair of socks with their wetsuit boots for the same reason. Try a pair of seamless airline socks. You know the type. They often give them to you on long-haul flights. Sophisticated socks intended for runners are constructed from two layers. So try two pairs of airline socks. Result? Luxury! Wear two pairs of seamless socks with your wetsuit boots and you won’t look back. They have the side effect of making it easy to pass your feet through the legs of your wetsuit too.

    Use a Weight Harness. Instead of strapping a lot of lead around your waist where it might ride up or slip off your hips, or instead of using an integrated-weight system of a BCD that might lead to your weights being positioned too high up your body, which in turn puts your fulcrum too far from your feet (leading to inversion in a drysuit) use a weight harness. By adjusting the supporting shoulder straps, you can wear your weights down by your hips. This not only makes carrying the weight more comfortable, but it puts the ballast where it needs to be. A properly designed weight-harness allows you to drop the lead in an emergency yet keeps it totally secure at all other times.

     

  • Photographing Sharks

    It’s easy to impress your non-diving friends and neighbours with the photographs you might take of sharks. Shark encounters come in a number of types: Chance encounters such as you might get ocean-roving oceanic white-tip sharks, encounters where currents attract requiem sharks that enjoy surfing on the flow, encounters with bottom feeding sharks such as nurse sharks and leopard sharks that like to lie up and rest during the day, and where sharks are feeding.

    The normal rules of underwater photography apply, in that it’s best to use a wide-angle lens and get as close as possible. Reduce the amount of water between your camera and the subject.

    Oceanic white tip shark Ocea-roving oceannic white tip shark

     

    Ocean roving sharks tend to be close to the surface so it’s quite possible to get reasonable pictures without an underwater strobe or flash but these are ambush predators so designed as to offer a low contrast image to intended prey. A correct flash exposure can give contrast and add drama.

    They tend to swim around 6m deep, constantly investigating anything that might be the source of a meal. That is why they approach divers, often only to turn away at the last moment when they consider us to be animals too big for them to take on. Sharks appear to judge size by height rather than length so if you want a shark to come close, present as small a frontal area as possible by being horizontal in the water. Go vertical and you will almost certainly scare off such a shark.

    Those sharks that lie about during the day such as nurse sharks can be approached with caution so as not to disturb them and you will have time to get more than one exposure adjusting the lighting and exposure to suit. The same can be said of white-tip reef sharks, although these are much more skittish. They lie about on the seabed during the day because they are able to force oxygenated water through their gills without forward motion like most other requiem sharks, but be aware that because they are grey and again designed for ambush, they need careful lighting just the same.

    Scalloped hammerheads at a cleaning station Scalloped hammerheads at a cleaning station

    Then there are the cleaning stations. Find out from the local dive guide which fish are the resident shark cleaners and find where they are aggregating. Then you just need to be patient, keeping as still as possible, waiting for the sharks to approach for a visit to the manicurist. It’s the only way to get pictures of scalloped hammerheads because they are so skittish. You need to sort out your overall exposure so that the background is reproduced an acceptable blue, adjusting the power of the flash (or strobe) to suit the foreground shark.

    When it comes to feeding sharks, things become a lot more frenetic. You need a fast shutter-speed but you will be limited to the fastest speed with which your camera will allow you to synchronise your flash.

    Sharks feed in two distinctly different ways. When chasing live prey they become very agitated and it’s best to keep clear at this time, even exiting the water. Sharks have more senses than we do but it’s a fact that they have a nictitating eyelid that covers their eyes to protect them at the moment of biting so that they virtually do the last part of an attack with their eyes closed. Mistakes can happen. Anyone who has attended a night dive at Manuelita Island near Cocos will attest to the fact, it can be chaotic, and that’s when it’s only little white tip reef sharks start hunting small fished by the light of the divers torches. Bigger sharks can explode with energy when they sense a live prey.

    White tip reef sharks competing for live prey at night. White tip reef sharks competing for live prey at night.

    On the other hand, when sharks sense there is a meal of carrion to be had, they are much more leisurely in their approach. There are no vibrations of injured or dying fish to excite them or ring their dinner bell, just the odour of an easy meal wafting on the ocean currents. So they tend to swim round in an orderly manner.

    Staged shark feeds such as they often do in the Bahamas and some parts of the Caribbean will give any diver witnessing the event that sharks, although impressive beasts, have a pecking order and act in an orderly manner so that they do not risk injuring each other. They still move quite quickly so you will still need to choose the fastest shutter-speed you can, in order to get sharp pictures. If you do not, the flash will record a sharp image but there will also be a less sharp ghost image due to the daylight exposure being too long.

    Using twin flashguns can also be counter-productive because those guys in the grey suits need a bit of contrast to light them up with plenty of shape and contour. It’s one occasion when the single flashgun reigns supreme.

    Caribbean reef shark at a staged shark feed. Caribbean reef shark at a staged shark feed.

    With plenty of sharks attending a staged feed, you won’t be able to judge where any are at a given moment. You’ll need to take a lot of pictures because inevitably one animal will obstruct your view of another, many times when you release your camera’s shutter. If you shoot RAW files, you’ll be able to adjust these after the event and not have to keep adjusting your flashgun’s output to account for sharks being at different distances from the camera.

     

     

     

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