The reason for this is that the algorithms and software packages used to set the cameras automatic programs have been developed for use on land, in conditions that are totally different to those found under water. On land, we don't find everything drained of colour and contrast and rendered with a cyan and blue cast. The range of light differs under water too, with sometimes extremely bright tones at the surface and almost blacks at depth.
This large "dynamic range" causes difficulties for the auto programs, and they tend to compromise and over-expose everything as a result. Some compact camera models don't have the facility to shoot in complete Manual mode, and some of those that do have access to the manual settings only via menu options. I marvel at underwater shooters who have come back from trips with outstanding images knowing that every time they've changed settings, it was done by scrolling through the menus. The perfect scenario would be just two well-placed controls to adjust aperture and shutter speed, and the ability to do it on the fly. The new Canon Powershot S120 compact camera does exactly this, so I begged those nice guys at Cameras Underwater in Cornwall to send me a system to test.They kindly sent me the S120, a Recsea housing plus a tray and arm system to put on the diver test track.

The Camera
I don’t have the space to detail all the features of this brilliant little camera, so I’ll cover the bits that are pertinent to the underwater shooter. 
The S120 is a direct replacement for the popular S110 and shares features from Canon’s top-end G16 camera, such as its 12.1 million pixel back-illuminated CMOS sensor and Canon’s latest Digic 6 processor.
Low-light performance has been improved significantly, and the camera can shoot at 9.4 frames per second (fps), though that’s in jpeg only. The camera loses the ability to continuously focus in this machine-gun shooting mode.
Canon says that the autofocus speed has been improved and that the camera will focus 50% faster than the S110, which provides an advantage, especially with skittish subjects.
The S120 is the first S-series camera to employ a lens with an f1.8 aperture. Its diminutive dimensions also make this the slimmest camera in the world to feature 1.8 optics, and it has a 5x optical zoom starting at 24mm.
The camera can record image files in Canon’s RAW format – these can be regarded as digital negatives when compared to the film cameras of yesteryear, with the RAW format saving all the information captured on the sensor without dumping anything to reduce the file sizes, as is the case when shooting in jpeg file formats...

Post-production software such as Adobe’s Photoshop and Lightroom RAW converters offer a significant advantage when processing images in the digital darkroom. White balance, colour temperatures, exposure, highlights and shadows can all be adjusted easily and quickly.
The camera has some other features that set it aside from the rest, such as the facility to defocus the background.
This takes two images simultaneously, one in and one out of focus, then blends them automatically to give a result akin to those shallow depth-of-field shots captured on DSLRs.
Other features are of no use under water, such as the touch-sensitive 3in LCD screen display or the Star mode for shooting-star trails at night, but these are useful additions when you get the camera out of its housing after a day’s diving.
The S120 does have a very capable Video mode, however, and can record in 1080p HD at 60fps for smooth results.
The controls are thankfully minimalist and reasonably intuitive, with a large ring around the lens base for shutter-speed control and a smaller ring at the rear for aperture adjustment.
The large ring control can also be used for other functions such as ISO setting via the ring-function button. There is an easily accessible menu, video and playback buttons plus macro, flash and bracketing controls.
The small pop-up flash, which can be set to minimum, medium or maximum output, is
of little use under water unless it’s used via fibre-optic cable to trigger a larger dedicated underwater flashgun such as those from the Inon, Sea & Sea or Ikelite stables.
The whole camera package measures about 100 x 60 x 30mm with the lens in its closed position, and it weighs in at only 217g, including card and battery.

The Housing
There are a number of housings available for the Powershot camera. I chose an all-metal version as I headed out to the blistering, sun-drenched waters of the Maldives to put the camera through its paces.
Some of my older Perspex and acrylic housings have warped in this hot climate in the past and consequently flooded the cameras, ruining my holidays. I didn’t want to take any chances on this trip.
The Recsea S120 housing is constructed from corrosion-resistant aluminium alloy and depth-rated to 100m. All the camera controls are accessible, with the emphasis on the aperture and shutter controls.
A large, easy-to-grip notched ring sits at the base of the lens opening and can be operated single-handed to adjust the camera’s shutter speed. The ring can be removed for cleaning via a lock and release mechanism.
The aperture control mimics the camera’s adjustment ring and can be pressed at the 3, 6, 9 and 12 o’clock positions to scroll through menus or zoomed playback images and also to move the focus area.
The centre OK button is large and also easy to use. Four more push-buttons give access to the menu, video record, playback and ring-function controls on the camera.
At the top of the housing are controls for the mode dial, zoom and the camera’s on-off switch.
The shutter release sits at the front top right and a thumb pad sits on the opposing face to make it easy to grip the housing when actually taking shots.
A small knob on the side of the housing will pop up the camera’s flash. The housing is supplied as standard with flash mask and an external strobe connection mount that takes a Sea & Sea type fibre optic cable.
The LCD screen is completely visible via a clear acrylic window, although this makes the touchscreen feature inaccessible.
The flat glass lens port has a 67mm threaded adapter to take an external wide-angle or macro lens, and will also take an adapter for Inon LD or AD lenses. A hotshoe mount at the top of the housing will take one of the many fittings for strobe or focus/video lights. A chunky lock-and-latch closure system completes the package.

The Arm System
To get the best results from this camera under water, an external high-powered dedicated strobe should be included in the system.
This needs to be mounted on an arm mechanism that is infinitely adjustable and mounted to the camera and housing.
The UN Arm Systems Grip Stay is a tray and handle that attaches to the Recsea housing with two standard tripod socket screws (1/4-20). The system is expandable via a 1in ball-mount and UN screw clamps to hold everything in place.
The UN Arm Systems components are made from marine-grade alloy, with an attractive royal blue anodised finish. The tray handle has a soft foam grip for comfort and traction.

In Use
I added one of my Inon Z240 strobes to the camera system, linked via fibre optics, and took the whole package under water in the Maldives’ Ari Atoll. The camera was set on Manual mode and the white balance set to Auto.
I started the dives with the ISO set to 100, with the view that this could be adjusted easily via the ring-function button if and when the need arose. My first impressions were just how light and unobtrusive the set-up felt, a far cry from my much-loved but bulky DSLR system.
The angle of view offered by the LCD back-screen was also impressive, meaning that I could shoot without the need to get directly behind the camera. This offered a significant advantage when approaching easily frightened subjects, or those that were tucked under small overhangs.
The camera controls were easy to access via those mimicked on the housing. I especially enjoyed the fact that I didn’t have to keep dipping into the menu system to change settings, which made the whole point, adjust, shoot scenario an absolute pleasure. I could concentrate on subject choice, composition and exposure, instead of battling with a complicated bank of menu options.
The final images were clean and noise-free up to and including ISO 800, but with so much ambient light on the Maldivian reefs I shot mainly at ISO 100 at an f-stop in the f2.5 to f4 range. Shutter speeds varied from 1/60th to 1/250th second for motion-blur-free images.
I found the zoom very versatile. At its widest I was able to get good coverage while still remaining close to the subject – any wider and I would have needed a second strobe to cover the whole scene.
Zooming right in at 120mm reduced the angle of view significantly, but meant that I could capture medium-sized fish portraits easily.
Set to Macro mode, the camera focuses very close indeed – in fact I had the feeling that I could focus on dust inside the lens port. The problem with being this close is actually getting any strobe light on the front of the subject.
Small non-skittish subjects like nudibranchs would provide fantastic macro subjects with this camera, because the whole set-up is small enough to let you get level with or below them, and move away from the standard shots of their backs from above that seem to fill every photographer’s image collection.

The way I generally shoot with my DSLR under water is to first set the f-stop for the depth of field I require. I then take an exposure reading for ambient light around midway in the water column, and adjust the shutter speed to give around a half-stop less light for the given meter reading, set the strobes to mimic the f-stop and flail away with the camera.
With the S120 I could shoot in the same way. The small exposure scale at the base of the LCD display was a little difficult for me to see but seemed accurate enough. Set to spot metering, it gave a good guide as to the shutter speed needed for a correct exposure.
With easy-to-use controls for aperture and shutter speed, the Powershot S120 could be used in the same way as my DSLR, but at a fraction of the size and weight. The results were very pleasing, and I’m sure that with a bit more practice they would improve significantly.
I didn’t get a chance to fully test the video capability as I didn’t have a bright video light, but the short bursts I did take in ambient light looked clean and sharp on my iPad.
I was mightily impressed with the S120 and Recsea combination. The only problem is that I know I’m going to have to raise my game with my own set-up.
Dublin-based Jackie Campbell won the BSoUP Open Portfolio with six stunning images captured exclusively with a Canon S90 (Who Needs A DSLR?Anyway?, May). That’s a camera three generations older than the new S120 and is an indication of just what can be achieved with this little set-up.

Canon Powershot S120
PRICE £349
LENS MAX APERTURE f/1.8-f/5.7. 35mm, equivalent 24-120mm with optical 5x zoom.
MONITOR LCD 3in touchscreen
DIMENSIONS 100 x 60 x 27mm
WEIGHT 198g without battery and card
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Recsea S120 Housing
PRICE £650 (camera and housing combo £900).
ACCESSORY LENSES 67mm threaded adaptor
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UN Arm System
PRICES Grip Stay tray £70. Ball base £16. Clamp £20. 145mm double-ball arm £25.
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