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Choosing a D-SLR Body for Underwater Photography

By Steve Warren

There's a massive range of D- SLR cameras on offer to underwater photographers. Yet, despite the choice, only a handful of camera models are normally chosen by top professionals and accomplished underwater photography enthusiasts. For most people an underwater D- SLR system represents a very considerable financial outlay. So getting the right equipment from the beginning is very important. Failing to do so will leave you frustrated as you fail to get the images you'd anticipated your expensive system would deliver.

The costs of an underwater housing system are much the same regardless of whether you choose a bottom of the range or top of the range camera. It's normal for aluminium housings to cost more than the camera body they contain. The lenses underwater photographers use tend to be specialist fisheye, wide - angle and macro lenses - all lenses aimed at serious amateur and professional photographers and priced accordingly. Seen against the true costs of owning an underwater D- SLR outfit, it's easy to see why a couple of extra hundred pounds spent on the camera body that will be the centrepiece of your system is likely to be money very well invested.

So what are the features that will ensure your D- SLR camera meets your expectations now and long into the future? What do experienced underwater photographers look for in a camera and why?

Let's start by considering actual image quality. Most D- SLR cameras today will boast a minimum of a 10 megapixel sensor. It's easy to get seduced by the idea that more megapixels is better - and to some extent it's true. But we also have to be realistic about how much image quality we really need or can even perceive in our photographs. If we step back and look at film, most serious photographers, including underwater ones, used 35mm cameras. This was despite the availability of medium format cameras shooting much larger - and thus higher quality - negatives. The reason 35mm prevailed was that most photographers simply didn't print their images large enough to justify the added expense, complexity and bulk of medium format cameras. The same is true of D- SLR technology. For most amateur and many semi - professional underwater photographers it's likely the image quality delivered by a 10 Megapixel APS - C format camera will exceed their needs. For the few underwater photographers who make a full time living from their images and who are shooting for top publications or picture agencies, the use of the highest quality and latest technology may be a pre condition of maintaining their career. The cost of owning the latest camera and housing systems is justified by their earnings from that equipment.

Sensor size is another point to think through. APS - C (compact sensor cameras) are the most popular with Ocean Optics amateur underwater photographer clients. Full frame is used by about two thirds of our parttime professional clients. Our full time professional clients predominantly choose full frame. Full frame does yield higher image quality for larger prints, allows the subject to be enlarged with less quality loss from part of the frame (useful if you haven't been able to get close enough to your quarry) and shows less noise compared to an APS - C camera set to the same ISO. Interestingly, one way to improve low light capability is to use fewer pixels, but make them larger. So cameras built for low light work may offer fewer MP than you might expect, but should yield lower noise than an equivalent size sensor with many more, but much smaller, pixels on it.

When choosing sensor size it should be remembered that full frame isn't automatically "the professional format". Both Nikon and Canon offer professional camera bodies that are not full frame.

You also need to consider your choice of lenses when choosing your format. Because of cropping, full frame lenses, typically macro's, require you to back away to get the same area into your shot when using the APS- C sensor. In low viz, common in the UK, this can be a serious limitation. So full frame may offer an advantage. Wide-angle lenses generally need to be matched to the sensor size to be effective. A limitation of the full frame format is for fisheye photography. Though fish eye lenses are made for full frame cameras, Tokina have made a hugely successful fisheye zoom, overcoming the two big problems of underwater fisheye photography - that the fisheye is to wide for the subject you've found and there's nothing you can do about it under the water! However this lens is only made for the APS - C sensor. More is explained in our guide to choosing D- SLR lenses.

But there's more involved in getting a great image technically than just the number of megapixels and the size of the sensor. Dynamic range is also very important. Dynamic range is the ability of the camera to record detail in bright and dark areas in the same picture. For underwater photographers the ability to deal with strong highlights and very dark areas simultaneously is important. We often shoot against the light - from inside a dark cavern into bright sunlight for example. Or the sun is in the top of our pictures, creating a very harsh, bright highlight, though the majority of the same shot is taken in much more subdued light. Wide dynamic range helps prevent the sun burning out the image, while retaining detail in the shadows. Poor dynamic range was a bugbear of the first affordable D- SLR's and one reason Ocean Optics encouraged our clients to hold off buying early D- SLR cameras forserious underwater photography.

Low light is a fact of life for underwater photographers. Even under ideal conditions of clear water beneath tropical skies at high noon, half the sunlight is lost through reflection, absorption and diffusion within the first few metres. During the times of "magic light", just after dawn and just before dusk arrives, there's much less light but much more opportunity to be creative. Also the deeper you dive, the less light there is. Some of our images may even be taken in near dark conditions such as inside a shipwreck with very little natural light to work with. In these situations you may be forced to increase the ISO or sensitivity of your camera, especially if you need a fast shutter speed to freeze movement, prevent camera shake or reveal shafts of sunlight. Increasing the ISO will increase the noise and this will become increasingly apparent in your photographs. A breakthrough in D- SLR's in the last couple of years has been the ability to keep noise to an absolute minimum even at very high ISO settings. This has opened up a world of high quality low light shooting to underwater photographers, making images possible that could not be done nearly as effectively on film or with earlier D- SLR models.

Autofocus also tends to be less easily fooled and faster on higher end D- SLR models. Underwater photographers tend to ask a lot of autofocus. Because we may need one hand to steady ourselves or hold a strobe, or sometimes because of a housings poor manual focus control placement or the fact we are using lenses which are impractical to focus manuallywhile inside a housing, we do rely on it working properly to a very large extent. But autofocus underwater is presented with two conditions that work against it - poor light and low contrast. Adding to the problem is that much of our photography is done at very short distances requiring the lens to be more finely adjusted for sharp focus, requiring greater and more frequent changes to the focusing distance to be made as we or our subject move. This is especially true when using telephoto macro lenses with moving subjects like fish. So powerful motors are needed to quickly drive the lens to the point of critical focus. Sluggish motors will mean you may well be waiting for the lens to find focus on a subject that has already departed. So your camera needs an auto focus detection module that works well in low light and low contrast conditions and either built in motors powerful enough to drive a tele macro lens to the sweet spot fast or the ability to use lenses with built in matched motors - as used by Canon and increasingly by Nikon. Inevitably the best autofocus performance will be found on those high end cameras aimed at the serious amateur and professional photographer.

Viewfinders must also be given careful consideration. At the time of writing most live view systems allowing use of the cameras built in LCD monitor for shooting pictures,(like you use a compact camera) had proven impractical to use underwater. They were too slow and interfered with focusing. This leaves photographers dependent upon seeing through the reflex viewfinder while the camera is inside a housing and the diver is wearing a facemask. So it's unfortunate that the eyepiece upon which we rely so heavily is so problematic. The reason is that the camera designer normally assumes you will have your eye right up against the eyepiece, or, on a few cameras, possibly wearing low profile spectacles. When your eye is forced back from the camera eyepiece it often becomes impossible to see the whole of the viewfinder image. Using a D- SLR underwater always forces your eye back because of the thickness of the housings pressure hull, the clearances needed for rear mounted controls to be operated by plunger type push buttons and the volume of your face mask - even if it is ultra low profile. It becomes easy for unwanted clutter to enter the edges of your photograph unseen or to clip important parts of your subject (like heads and tails) because you can't see them clearly and have to guess whether they are really in or out of shot. APS - C camera viewfinders tend to be smaller than full frame cameras, making them even harder to use. Full frame cameras have larger eyepieces similar in size to 35mm film SLR's. But it must be remembered that underwater photographers found normal viewfinders fitted to most 35mm cameras hard to use. Serious 35mm SLR users sought out professional cameras that took special oversized viewfinders that made viewing underwater much more effective. To be able to clearly see what you are doing you'll find almost all D - SLR camera viewfinders will need to be modified by using special optics built into the housing. A lot of misinformation exists around the types of viewfinders on offer from housings manufacturers. Our guide to SLR housings will help explain these issues.

Other considerations when choosing a camera body include ease of use, durability and size and weight. Underwater photographers tend to use only a few key controls under the water. These include shutter release, shutter speed, aperture, zoom and playback. How easy these are to use is dependent upon the layout and operation of the controls on the camera, how they are operated through the housing and how easily you can reach and operate the external housing levers, buttons and knobs. Professional cameras are often more minimalist than amateur cameras having less cluttered menus for example to ensure the camera is fast to operate. Amateur cameras tend to have more bells and whistles which an underwater photographer is unlikely to use. Higher end cameras are also more durable. Bodies are tougher to resist impact, humidity and vibration and are built to withstand repeated shooting day in, day out. If you plan to have an underwater camera system that works flawlessly for many years to come with little downtime or expense for servicing and repairs, a high end body is likely to be a better bet than a low end body. Our cameras are subject to humidity in many of the locations in which we dive due to extremes of temperature (after all the camera spends most of its time outside the housing on a trip), get knocked about during entries and exits and are subject to vibration and knocks from flying through turbulence, heavy landings and being aboard boats banging around on the high seas. Large D- SLR cameras and necessarily larger housings add volume and weight to your luggage. Underwater, cameras with deep bodies can make it tougher to shoot with your camera at seafloor level - a technique often used in close up and macro photography.

Pro camera bodies may offer other benefits. Higher flash synchronisation speeds is one. A lot of underwater photography is based around balanced light shooting - combining flash fill to light and add colour to the foreground with sunlight to illuminate the background. High flash sync speeds, such as 1/250th, make it easier to match flash and daylight exposures and freeze shafts of light for creative effect. High end cameras may also shoot more images in RAW before the buffer fills up and you have to stop shooting. This can be especially important when you want to use motordrive to work with fast moving pelagics like dolphins.

Another innovation is the ability to shoot video with a stills camera. For some time video cameras have been able to take video footage and stills cameras have been able to record video. However quality has tended to be mediocre when cameras are used in their "secondary" role. Recently this has changed with some D- SLR's now able to shoot genuine high definition video at the 1080 broadcast standard. The Canon 5D MK11, for example, has been used to shoot a season of the hit show "House" and we have supplied a housing for use by National Geographic Television for a major underwater series. The compact size of D- SLR's makes them much more manageable that the smaller broadcast camcorders like Sony's EX3. A housing for a D- SLR typically weighs less than three kilos while an EX3 housing may exceed 10KG.

It can be tempting to save costs by buying secondhand. When buying secondhand it's important to know why the seller is moving his equipment on. Is he giving up underwater photography or has he found flaws in his existing equipment which are forcing him to upgrade and would those flaws impact on your own photography? For example an underwater photographer working in British waters might feel entirely justified in moving to a D - SLR which lets him counter low light conditions by using much higher ISO's than his current camera allows, But if you only intend to shoot in tropical conditions, this feature might be much less important to you. So it could be a good buy. But if he is upgrading his equipment because the housing is clumsy to use and the viewfinder hard to see through or he can't get it serviced in the UK, these are all good reasons for you to avoid it to.

Steve Warren

INON UK Instructor - Examiner