Compact digital camera performance is advancing all the time, but it's no accident that most underwater photographers who get into print use SLRs. The rules are exactly the same as on land and SLRs simply have less compromises and more to offer than most compacts. As well as generally better performance, SLRs have several compelling advantages over compact digital cameras, but even those don't make them a home run for every diver. Let's look at the ins and outs of taking an SLR underwater... there's more to it than meets the eye.
In this two part guide we'll examine some of the key points and hopefully help to steer your mouse towards the right options as it as it hovers over the 'buy it now' button;
- The size and weight of the whole kit - stay safe and avoid excess baggage!
- Take your current SLR system into the sea or start afresh?
- What lenses (and ports) will you need?
- The secrets of strobes
- Will the parts you want work together?
- Can you upgrade? - Plan ahead for strobes and lenses
The SLR factor
Don't get me wrong, you can certainly be creative with a compact, but some aspects of your photography are unavoidably limited by the built-in lens and flash. Although you can connect strobes and lenses to expand your horizons, the shots you are admiring in books and magazines will nearly all have been taken with SLRs. Using the same lens to directly view and shoot the picture is much more intimate and informative than even the best display, and an unexpected bonus is that your shooting will be steadier with the camera resting on your head!
Because SLRs use different focus technology, the delay between pressing and shooting is much shorter. You'll also notice that they are ready for the next picture straight away, so you can shoot almost as fast as you can pull the trigger. This means bigger memory cards, more backup storage and, as they can all shoot RAW, maybe some fancy new software too.
The right reason for taking an SLR underwater is because you want more creative options to stretch your photography. It won't cure sloppy technique and can't make you an artist. Plenty of people have cameras underwater now, so don't bank on becoming rich and famous either – enjoy it for what it is; a hobby. With luck and practise you can make more of it, but it's supposed to be fun!
Think big (sensor)
Every digital camera has so many pixels that it's very hard to isolate detail information in just one. This means that under difficult conditions information spreads from one to another, giving rise to noise - grainy or blotchy disturbance on the picture. Most cameras can take good pictures in good light but the extra size and space between SLR pixels improves their performance in low light. It is a truism that a few good pixels are better than lots of bad ones.
The sensors on compact digital cameras are very small compared to SLR sensors, maybe less than a 15th of the area, but the difference between different SLRs is much less significant. This means that while the difference between a compact and an SLR is huge, the variation between SLRs is relatively small. There's no standard size for digital SLR sensors, the 35mm size used for film itself was the result of Leica deciding to try recycling reels of cine film. Sensors behave differently from film, so while the largest sensors have the best noise performance they need especially good (new) lenses. SLRs are very much part of a system and it's best to look into the best overall system for you before you jump in.
Another factor which SLRs introduce is limited depth of field (DoF); the range of the picture which can be sharp. Compact cameras have a depth of field of course, but it is much larger than for an SLR for identical settings. This is another result of the large sensors used in SLRs. Control of depth of field is part of the look and allure of SLR photography – the option to isolate your subject in front of an attractively blurred background.
Work that body
Beside the the cost of the other components needed to complete an underwater system, the price of an affordable SLR body is a minor factor. The best strategy, I think, is to have have two identical bodies when you go away. Although there's no harm hedging your bets and having a second system for diving - in the same way pros will have a smaller, spare body in their bag - the risk is that bad luck will introduce your diving body to some seawater and the large surface body won't fit in the case.
Big bodies carry all the latest features but underwater they aren't always necessary or even easy to exploit. The more fundamental properties are of paramount importance and most of these are more to do with lenses and control than new ways to track faces or fire off tens of frames a second. Even how the body feels in your hand is unimportant, as the housing will introduce new grips and controls. The best tailored housings will attempt to offer access to all the camera controls, but some of the generic housings miss some out, or you have to use quite complicated multi purpose levers to swap between various controls.
The chief downside of an SLR underwater is the size of the cased camera, it stops many people even considering them. For this very reason I favour smaller cameras underwater. A housing still makes them large, but imagine the size that one of the mega SLRs with mock motordrive grip would become when housed! This is much less of a problem in clear, bright, blue tropical water, but in potentially dark or more challenging waters it's a real consideration. Much more than adding a compact camera to your diving set up, carrying an SLR can dominate your dive and can prove a real liability in an emergency. A large housed SLR with a pair of strobes, big lens and dome port could weigh up to 10kg (and cost more than £7000), so make sure you are ready for it! There's a lot to be said for downsizing underwater, at least to begin with. The good news is you generally don't have to use as many extras underwater as you might imagine, so a good, small body will get great results and lighten the load... physically and financially. A small SLR setup can weigh as little as 4kg (and cost less than £2000).
N.B. The weights suggested are approximate surface weights. Underwater the apparent weight will be much reduced but can vary a lot depending on case material and which port you're using.
If you think you might one day want to take your camera underwater, checking that a housing exists at the outset is a good idea. Some cameras will have a good choice of housings; an own brand housing and maybe one or more third party cases. Other cameras just don't suit making a good housing or don't have one made for other reasons. The few own brand housings are often cheapest, but not by any means poor. Third party housings can appear tougher but often the most obvious real difference is that they are much bigger. This is because they can sometimes be a generic container which is customised only by having different controls fitted. At the top of the market are some beautifully engineered housings which are machined from solid aluminium.
An SLR housing will usually cost more than the camera itself. It might seem that the housing is simpler and should be cheaper, but they are made in relatively very small numbers, and some are literally hand built. They are made from expensive engineering materials to tight tolerances and carry a lot of responsibility. All their ratings will be enough for all normal diving. Housings are usually quite conservatively rated, I have had no concern occasionally taking housings beyond their rated depths – but I do take my case maintenance very seriously.
Own brand underwater housings are very good value, but as yet only Olympus make them for their SLRs; their system is currently the only complete one stop shop for SLR users. I've used them for several years and it's been a really good experience. Own brand housings for SLRs, like compacts, tend to be the lightest, best fitting and only incidentally the cheapest.
Generic housings tend to be 20-30% more expensive than own brand but significantly heavier and larger. They can be somewhat over engineered as they must suit a wide range of applications. This should make them tough and, because the range of ports will be sold for many different camera models, those tend to be good value.
Top end housings often share the close fit of an own brand case, and are usually machined from solid aluminium which makes them very robust... This comes at a price, perhaps 3 or 4 times the cost of an own brand case. I would suggest that they are a good investment if you intend keeping your camera for several years. Although in these digital days, few people can resist the temptation of an upgrade for that long. It's good to keep in mind that you will almost certainly have to buy a new case if you upgrade.
One effect of the variety of SLR sensor sizes is that simply knowing the focal length of a lens in mm will not tell you much about its angle of view. For 'full frame' sensors the old film rules do apply, but for smaller sensor SLRs a 'crop factor' or multiplier applies. As soon as you understand about this factor, you'll see that there's actually a full range of lenses for all the systems, even though the numbers change! There are very few lenses which are unique to a particular system, so your choice is usually affected by quality, not range.
When underwater, most SLR photographers tend to use just two lenses. This is because circumstances and subjects tend to dictate that the most useful choices are macro subjects or wide angle views. Rather like portrait and landscape photography on land.
Macro is a game of skill with precise focus needed and limited depth of field available.
Macro lenses do vary in angle of view but not so much in size and shape. Underwater the longer (focal length) ones tend to be hard to use as they can be slower to focus, while short ones work but need you to be closer to your subject - which can startle animals and be hard to light. Typically the choice is in the 50-60mm range. These are prime lenses (no zoom), so you move to get the view you want... talk about old school!
Wide angle is creative; composition is difficult, huge depth of field can make it hard to isolate a subject.
Wide angle lenses are available in abundance; by film standards even your kit lens counts - but these days a 28mm equivalent view is just the start of wide angle. Serious underwater wide angle starts around 10mm now, for small sensors, with options down to 7mm. At this end of the scale the crop factors can make quite a difference to your field of view, so don't be thrown by the difference between systems. Many of these lenses are zooms, which is very useful, extreme wide angle can leave some subjects stranded in a scene and being able to zoom makes the lens more flexible.
There are two types of wide angle lens, most are rectalinear – which is considered normal. The alternative is fisheyes which give a rounded view of the world, while rectalinear lenses try to eliminate that distortion. Fisheye views are an acquired taste, but can look very cool!
You gotta have a system
Where you can pop a compact in a case and go take pictures of almost any style (with varying degrees of success), the same is not true of an SLR. Once housed, the camera and lens are off limits for the duration, so you need to make some choices before you jump off the boat. You need a port for whatever lens you have chosen, a strobe if you want to do anything other than ambient light shots and some metalwork to hold the whole lot together.
In Part 2 we'll go into fine detail about lenses and strobe options, illuminating those subjects and getting you closer to some more ambitious underwater photography.