John Bantin has been a full-time professional diving writer and underwater photographer since 1990. He makes around 300 dives each year testing diving equipment.

BACK IN THE MID-'90S, THE F90 (N90) 35mm single-lens reflex camera was the very latest offering from Nikon. All its electronic wizardry made it far superior to its predecessor, the F801 (8001). Also at that time, the NX90 housing, made by independent Japanese manufacturer Sea & Sea, was one of a raft of new clamshell submarine housings launched to cater for those who wanted to take their new Nikon under water.
     Now the F90 is obsolete, superseded by a couple of improved versions and finally replaced by the Nikon F100. But that's good news for underwater photographers, because there are now lots of F90 cameras available secondhand and, as any experienced photographer knows, one camera is never enough.
     The shrewd professional always carries a few identical cameras so that he or she can come back with the goods, even after some disastrous flood has converted expensive state-of-the-art electronics into something no more useful than a paperweight.
     I don't care if the camera inside my submarine housing has lost some of its anodising and is a bit shabby, as long as it works. The F90 is an unashamedly amateur camera made with lightweight materials, and in that sense bears no comparison with the magnificently constructed and fearsomely expensive professional Nikon F5, but it has all the features you need under water.
     The quality of its pictures is the same, provided you don't go fixing strong CU dioptre lenses on the front of high-quality wide-angle lenses.
     Many of the submarine housings available today are of the highest quality. However, they use small-diameter dome ports, which make a virtual image under water at a shorter distance than that on which the Nikon wide-angle lens will normally focus.
     To get the lens to focus, you need to reduce its focal length so that the amount of back-focus provided when it is fully racked out is sufficient to get that super-close virtual image sharp. Close-up lenses of around +4 dioptres are often specified.
     Designing wide-angle lenses is the hardest part of a lens manufacturer's job. Good-quality ones usually include many individual elements, and this is reflected in the cost. They are normally computed to perform best when focused on infinity, because most are sold to amateurs, who use them for wide views.
     Fixing a £50 close-up lens on to a £500 prime lens instantly does away with everything you have paid for. The softening of the image is usually most noticeable at the corners.
     I have been using a submarine housing with a large-diameter dome port that needs no close-up supplementary lenses on my expensive Nikon optics. This has been very successful, but after far more than 1000 dives has become rather tired. The port has become too scratched on the inside for my liking - so I decided to get another.
     It seems that underwater camera-housing manufacturers rarely hold any stock. When they get an order, they go out and get a casting made, which can take six months or more.
     So obtaining a replacement quickly was not as easy as I had imagined. But the British importer still had stocks of the latest Sea & Sea NX90(Z) housing, so that's what I got.
     All the advantages of through-the-lens (TTL) viewing are conferred by 35mm SLR cameras and, in common with many contemporary cameras made by other manufacturers, the F90 also gives sophisticated TTL exposure control. If you're planning to get into cameras and submarine housings, this is a jolly good time to do it with a secondhand F90, but remember, those stocks of NX90Z housings won't last forever.
     The NX90Z is a small unit as they go. All the controls of the camera are worked by mechanical connections to the controls of the housing. The camera slides in quickly on a pre-mounted tray, which instantly locks in place with a large cam-lever.
     The port, flat for macro or domed for wide-angle, is mounted on a bayonet and locked in place by a pin system operated from inside the housing. There is no danger of it being inadvertently rotated undone on the boat.
     There is full control of manual or auto focus (with a focus-lock button), and manual control of the aperture and shutter speeds should you wish to use any auto programme or the manual-exposure control setting of the camera. In fact virtually all the F90's controls are accessible under water.
     I chose the 21cm diameter super-dome but there is a smaller dome and also a compact version for those for whom image quality is less important than ease of handling.
     There are two bulkhead connectors for electronic flash, so if you are using Sea & Sea flashguns you can enjoy full flash auto exposure with two flashguns. It can combine that with daylight, thanks to Nikon's sophisticated multi-segment matrix metering.
     I did find it quite difficult to access the film-rewind controls, and had to withdraw the camera from where it was mounted each time. I have often climbed back onto a boat and talked a crew-member through rewinding a film and reloading a second roll, because I've been dripping wet. With the NX90Z I might have to consider stripping off my suit and using a towel if I need to do this.
     The viewfinder optics are not the best either, though good enough. You need to scan with your eye to see the electronic display of aperture, focus and frame number, and then look at the image area separately. It's something to get used to, and the NX90Z housing is not alone in this.
     I also had to apply black tape to the white Nikon label on the camera front and to some of the control rods, to avoid any danger of them reflecting on the inside of the port. The same goes for the many warning labels inside the port mounting (these will peel off).
     The port itself is suitable for use with a full-frame fisheye lens, and as such has a minimal lens hood. This leaves the clear acrylic area vulnerable to damage, and I spent a whole afternoon with the Duraglit, polishing out a set of scratches from an unnoticed rusty metal protrusion during a wreck dive.
     You must also be very careful how you replace the main O-ring of the housing, as it is prone to pop out of its groove as you close the clamshell.
     My only other criticism is that this housing is much more lightweight in construction than my previous professional housing, and I suspect it will not last as many years. Who knows? My housing works hard, doing many dives each month. It spends no time at all under my bed, nor is it treated as an object of desire.
     Expect to pay about £300 for a good-condition F90 camera secondhand, and about the same for a secondhand wide-angle lens. A new Sea & Sea NX90Z housing with dome port and lens aperture control ring as shown costs £2083.

Another fine mesh
THE STAHLSAC DELUXE MESH BACKPACK IS BIG. It measures around 75 by 42cm, so will accommodate a whole set of dive gear. I found it useful to pack it in my main luggage and then bring it into action once I had got where I was going.
     It easily took my fins, suit, boots, regulator, BC and mask. It's perfect when going on a boat.
     The Mesh Backpack also has a dry pocket which is sealed by rolling it up until the two opposing surfaces of velcro meet to hold it.
     I found this section would hold my shorts, T-shirt and a rain jacket should I have needed it. There is also an outer pocket (not kept dry) for things you might need in a hurry.
     The end of the bag is pulled closed by a lanyard and toggle, just like any other duffel bag.
     Once loaded, the whole lot swung easily on to my back and the padded backpack shoulder straps provided are just what's needed when you might be wearing little else.
     When diving was done for the day, and everything was packed in the Mesh Backpack, I found I could saunter ashore from the boat, dunk the whole thing in the freshwater rinse tank and then hang it up to drain ready for diving the next morning.
     It's my experience that Stahlsac bags are strongly built and last a long time. Although this is a mesh bag, it is obviously stronger than many others that might tempt you on price. All Stahlsac bags have a lifetime guarantee. I wonder whose lifetime that is?
     Of course, there is no security from prying eyes with this type of bag, and it would be a foolhardy person who checked it in at an airport.
The Stahlsac Deluxe Mesh Backpack costs £52.

Swivel on this in cold water!
Hydrotech's factory and warehouse conveniently overlooks an inland diving site that is exceedingly popular with divers. The people at Hydrotech must see plenty of regulators freeze up and go into free-flow during winter weather.
     Hydrotech imports the all-new Dacor Viper Metal, which distinguishes itself by the large metal inserts in the second stage which act as a heat-sink.
     They extract a little heat from the surrounding water (always more than zero degrees) and warm the air from the tank (often less than zero degrees).
     Now Hydrotech says that all the Dacor regulators it imports meet EN-250 Cold Water performance requirements, so let's just say that the Viper Metal meets them better!
     The first stage is unique in having a dedicated swivelling turret for the medium-pressure hose to the second stage. This promises to alleviate that snatched-from-the-mouth feeling you get with a hose that's not quite long enough when you turn your head to the left.
     The Viper has its exhaust port on one side, so you can choose to run it from over either shoulder.
     Brendal, of Brendal's Diving in the Bahamas, looked at it with interest when he saw a new bit of kit but his reaction was: "That'll be a wet breathe!". This, of course, is a criticism that can be levelled at any regulator which has a side exhaust.
     Conventional regulators with the exhaust port at the bottom let out exhaled air, and any water that might make its way past the valve at that moment is expelled with the next breath.
     It's only when you find yourself head-down or inverted that you might get water mixed with the air. The challenge has always been to design in a limit to that effect.
     With the Viper and its side exhaust, it's true that if you tilt your head well away from the exhaust port it will let back in a certain amount of water when you exhale. Then, if you happen to tilt your head in the other direction before inhaling, you will get some of it in your mouth. So you tend not to do that!
     It's a question of getting used to the foibles of a design. The first dive I made with the original Viper Tech was horribly wet, and then I seemed to crack the code.
     I found the Viper Metal very light in the mouth. I soon got used to the bubbles coming up the side of my face, as it usually does that with a conventional second stage. It's just that with them you never know which side the bubbles will come up on.
     The regulator was very comfortable and gave me plenty of air. In one or two instances, when I really heaved on it, it would gush a little more than I liked and, I suspect, went into a positive-pressure mode, but this happened less frequently than I remember the Viper Tech doing when I first tried it.
     Perhaps the manufacturer of Dacor products, Mares, has had a look at that and done something about it.
     All round, I found the Viper Metal a very attractive proposition, and I expect to see a few appearing in the mouths of divers who like to frequent those popular cold inland sites.
     Just make sure that the swivelling part is at the top when you mount the first stage on your tank, and you will enjoy a degree of freedom in hose routeing that you have never encountered before.
     The Dacor Viper Metal is available in A-clamp or DIN fitting and retails for around £300.

Dinky light is no toy
I had just got used to the idea that the best underwater lights come from northern Europe when I stumbled across Leone products. Leone is an Italian company which makes underwater lights for video and flashguns for photography, all with ribbed aluminium casings.
     It also makes a large range of underwater lamps, up to a massive 24V size to fire up a 300W bulb. It's the sort of light that can cause coral bleaching by raising sea temperatures!
     The biggest lanterns have dimensions dictated by the size of their batteries. This means you tend to have to put air in your BC to compensate, or risk floating irrevocably upwards should you accidentally become separated from your light.
     However there is also a system of lampheads with umbilicals that allow you to stow the battery-pack on your tank or elsewhere and carry less in the hand. Fixed weight in your kit like this can be substituted for lead on your belt. Leone can also supply batteries contained in a belt that doubles as a weightbelt.
     This also provides all sorts of possibilities about where you fix your light. You can hold it in your hand, or mount it on your head like one of Arthur Scargill's finest if you like. All the lamps are depth-rated to 150m.
     Looking at the possibilities, I liked the idea of the 6V Super HandyLight because it's so dinky.
     It measures a mere 21cm by 5.6cm in diameter and gives around 35 minutes of burntime with a 20W bulb and its conventional ni-cad battery. It takes five hours to charge fully from flat.
     Weighing in at just over half a kilo in air, the weight of the Super HandyLight proved almost negligible in the sea at around 200g. With the powerpack stowed in my BC, its effect on my overall buoyancy was insignificant.
     Its electromagnetic switch allows for one-hand operation and no chance of a leak because of a bad through-body connection, and its front glass is tempered and thick enough to allow continuous use even in the air.
     I found that the switch needed to be pressed in to turn it on or off, and this proved to be a slight problem because the light tended to come on in my pocket when I wasn't using it.
     The only precaution against accidentally switching it on is to apply an O-ring (attached to the powerpack lanyard) around the button of the lamp, which is provided with a groove for that purpose.
     That's OK for travelling, but far too fiddly to do under water.
     To test an underwater light properly, you need bright conditions. Yes, you read that right. Because your eye has such a wonderful sensitivity range, thanks to the rods and cones of the retina, any torch will light up the dark. Your eye adjusts accordingly. It's when you want to use a light to restore natural colours that its brightness counts, because it has to compete with daylight filtered blue through the water.
     The Leone Super HandyLight in 6V guise is obviously not as bright as something with a 100W bulb fired up with a 12V battery, but in the well-lit waters of the Bahamas it still proved useful in revealing the natural colours of the reef.
     Leone also make video housings, so naturally there is a choice of reflectors, from a spot effect that's ideal when using a lamp as a torch, to a wider beam that might suit wreck divers, and a very even wide-angle beam perfect for use when recording video images.
     Leone also make coloured filters for video effects, and a range of brackets and articulated arms on which to mount lights or flashguns.
     Every item in this vast lighting range is part of an interchangeable system.
     Leone products are imported by Cameras Underwater and the 6V Super HandyLight with umbilical as tested costs £328.

Mosquito no fly-by-night
I remember my first Vodafone. What a marvel. I could easily ring people from my car, provided I was near a relay station. Of course, it ran off the car battery, and the luggage compartment was filled with the necessary electronics. Now mobile phones fit in the palm of your hand and most schoolkids seem to have one.
     Suunto is the world's largest producer of diving computers yet, I am told, a year's production at its factory in Finland equals only ten minutes' worth of production at the Nokia phone factory. That's because there are a lot fewer divers than people in need of a phone!
     However, it cannot be denied that one of the most remarkable changes in our world during the past 25 years has been the miniaturisation of electronics thanks to the silicon chip and advanced battery technology. It would have been hard to explain to my Edwardian grandfather what is now possible. And progress seems unstoppable.
     Less than 20 years ago I was wearing a diving computer, the Decobrain, that looked like half the dashboard of a Ford Corsair strapped to my arm. The latest watch-like computer from Suunto is as slim and light as a Swatch and it does a lot more than the Decobrain ever did.
     If you thought the Stinger or its forerunner the Spyder were too chunky as everyday watches, the Mosquito is for you. It comes in a lightweight composite carbon-fibre casing rather than stainless steel.
     It's a watch, a stopwatch, a depth gauge and timer for free-divers, a full-function air computer and a nitrox computer. It will download with suitable software and interface to a PC. It has a backlit display. Do I sound too enthusiastic?
     In fact, apart from a couple of functions, it is almost identical to the Stinger. It doesn't offer a gauge mode (suitable for trimix divers), and its depth limit is only 100m, while the Stinger's is 200m. It offers five minutes of free-dive logbook, you cannot adjust the dive sampling rate (it stays at once every 20sec) and you can use only one active dive mode at one time.
     Where it does score over the Stinger is with its user-changeable battery, and new batteries sensibly come with a replacement cover in case you damage the old one in getting it off.
     I used the Mosquito alongside the Stinger for comparison. In a normal diving situation, the display was identical. The information was the same and the display figures the same easily readable size - in fact, as easily readable as the much bigger Suunto Vyper. I imagine we will be seeing a lot of Suunto Mosquitos adorning wrists in the future.
The Suunto Mosquito costs £269.