UNDERWATER HOUSINGS

by Andrew Dawson

"You expect me to put my F5 and best lenses into a box and take it 100 feet underwater?? Yeah right..." Hey, you risk your $40,000 SUV every day on the road, so what's the big deal? But seriously... Many people are wary of sinking their expensive SLR's into a hostile environment, and salt water definitely qualifies as hostile. The reality is you're not taking as big a risk as it might appear. Housing manufacturers understand that you're putting several BTU's inside their product, and they have a strong interest in making sure it works. (For the uninitiated, a BTU =Basic Toy Unit, or $1000 US) With reasonable care and feeding, housings can be very, very reliable. In fact, the Nikonos is way more prone to flooding than housings, and a Nikonos system is not a small investment either. Over the years, I've even had some minor leaks (through my own error), and it was as simple as drying off the camera, clean and lube the housing, and I was ready to go. The only catastrophic flood I've seen was a dive guide who smashed the front port on a rock underwater, and opened it up to the sea. Bummer dude... but it was pilot error, and it could've been avoided.

Why use an SLR underwater? For the same reasons as on land: versatility and more power to be creative. You can utilize any lens you want, although there's only a handful you would bother with. You'll have faster flash sync (1/250 in most cases), reflex viewing, more exposure options, and a host of other features. Although every working pro uses the Nikonos at times, housed SLR's are the standard.

(Sea & Sea housing for Nikon D100)

Every housing works fundamentally the same way. It's a metal or plastic case, usually molded to fit a specific camera, and uses silicone O-rings to create a watertight seal at the joints. Trusting a $5 O- ring to preserve your $2000 camera seems like madness, but the simplicity is what makes it work. Unless the O-ring is damaged or contaminated, it can work remarkably well. Ironically, as you dive deeper, the O-ring compresses under pressure and the housing becomes even more watertight. (Statistically, most floods happen in shallow water, or even the rinse bucket on board the boat.) If you're someone who hates any level of risk, there are insurance policies that cater specifically to u/w photographers.

THE NIKON CONSPIRACY COMES TO AN END

In the past, the vast majority of SLR housings were made for Nikon cameras. There's a simple reason. Nikon made a huge commitment to underwater for many years, although that has faded recently. More importantly, the most common underwater camera in the world is the Nikonos; therefore, every non-Nikon strobe unit ever manufactured was made to speak Nikon language. The result: housings needed to work with those same strobes, so the majority were for Nikon. If you were a diehard Canon-or-whatever user, you weren't completely out of luck. It was just more difficult to find compatible gear, and you had fewer options.

Digital cameras, not unexpectedly, have changed this equation in a huge way. DSLR's and compact digitals have ushered many new choices, as well as new problems with compatibility. Overall, many housings are still for Nikon, but this monopoly is soon to be ancient history. As with everything digital, changes come faster than Californians can elect their next governor. It's important to note that the biggest issues related to using underwater housings are optical issues, and not ones with specific brands, or even with film vs. digital.

WHICH CAMERA SHOULD YOU USE?

Back when everyone used film SLR's, there were only a handful of major players in the housing market. They were Ikelite, Aquatica, Sea & Sea, Subal, and Nexus; there are others that are less common, but work just as well. The most common film bodies still being housed these days are the Nikon N90, F4, F5, and F100. If you're looking to hold costs down, there are attractively priced set- ups for some consumer SLR's, like the Nikon N80 or Canon Rebel series. For the lottery winners, there are even housings in the works for the Hasselblad H1…

These manufacturers have stayed in the game, and are releasing housings for new digital cameras all the time. The digital era has also brought in new players, like OceanHaus, Olympus, and some who previously made only video housings, such as Light & Motion. Some of these new digital housings are incredibly small and lightweight compared to SLR howitzers of the past.

(Oceanhaus housing for Nikon Coolpix 5700)

The most obvious differences between housings will be the layout of controls. Naturally, one needs control of the basic functions: shutter speed, aperture, focus, trigger. From there it is largely a matter of taste; some F5 and digital housings might as well be the space shuttle for the number of controls they have. My own opinion is that most of the tricky extended functions won't help you that much underwater, so you don't really need a control knob for everything.

All housings provide a rear window to see through to your viewfinder. By the time it's in a housing, the viewfinder is far enough from your eye that it can be difficult to see the whole frame. Several housings provide an "enlarging" attachment to fix this problem. In many cases, it's actually reducing the overall size of the image so that you can see the complete finder. If you're optically challenged, this can mean some guesswork when it comes to critical focus. The consensus—for now—on LCD displays on digital cameras is that they work fine for checking shots post-exposure, but are not great for precise focus and viewing underwater.

(Rear view of Ikelite housing for Fuji S2 Pro)

Viewing is one area where some pro bodies (Nikon F3, F4 and F5) have a big advantage, since they can be outfitted with a sport or action finder. These large finders make it much easier to see focus and composition through a housing. When I switched from the N90 to the F4 with a sportfinder, I found my "keeper" ratio went up quite a bit, especially with macro. A sportfinder isn't exactly a cheap accessory, so many people choose not to go this route, although I would recommend it highly.

PORT OPTICS

The port on a housing is quite simply the window through which the camera peers out. Not too surprisingly, it is also a crucial link in the optical chain that ends up on film/CCD. Without getting into a re-hash of high school physics, we need to deal with refraction, the effect we see happening with this pencil.

A similar thing occurs when light passes through the glass port of an underwater housing; the light rays are bent due to refraction. This would just be boring high school physics, except that it creates definite problems while using wide-angle lenses underwater.

Trying to use a wide-angle lens, such as a 20mm, behind a simple flat port would be a serious mistake. The apparent lens angle would be reduced, making your wide lens not so wide anymore. Also, the image would be sharp in the center, and would get progressively softer toward the edges, all due to refraction. This effect is more severe with wider lenses; i.e., a 14mm will look worse than a 24mm. The solution is to correct these bent light waves with a glass dome or fisheye port. Every manufacturer makes dome ports to fit their housings.

(a typical dome port)

The positioning of your lens within the dome is important. Without slogging through a lot of physics again, the entry point of light into your lens--the nodal point--needs to be at the focus of the dome. Thankfully, this has also been considered in the design of housings and dome ports. By using extension rings or specific ports, you can match your dome to the exact lens you're using. If your lens is too far forward or back from the optimal position, you won't get the full benefit of the dome correction, and sharpness will suffer noticeably.

When using macro lenses, flat glass ports are actually preferable. The refraction effect is still there, but is not causing distortion and sharpness problems the way it does with wide-angle. In fact, the refraction through a flat port gives you some added magnification. A macro lens that focuses down to 1:1 will achieve about 25% better than that with a flat port. All housings can be outfitted with flat ports. About the only consideration is making sure the port is long enough so that your macro lens can extend fully.

(a typical flat port)

LENS CHOICES FOR WIDE-ANGLE

As mentioned in the article about general techniques, wide lenses allow you to eliminate as much water as possible between you and the subject. Typical choices with film SLR's are 14mm or 15mm (rectilinear), 16mm fisheye, 18mm, 20mm, or 24mm. All these lenses allow very close focus and still provide a wide enough view for good composition. Any less wide, and you are forcing yourself to back away from the subject, and saturation and sharpness are going to suffer. Which of these lenses you choose will be based on what your subjects are likely to be, as well as your bank account. Something like a 24mm (equivalent to the 20mm on the Nikonos) can be the ideal choice for animals that may not approach close enough for good composition with a wider lens. For images like reef scenics or shipwrecks, where you can get as close as you want to the subject, your lens almost can't be too wide. Using a 180-degree fisheye like the 16mm can make for very interesting shots, although it takes some getting used to its extreme coverage.

(Nikon F4 in Aquatica housing, Nikkor 18mm/3.5)

Wide-angle zoom lenses seem like a good idea, but actually involve some compromises when they're used in housings. Something like the Nikkor 17-35mm/2.8 is a great lens, but you run into trouble with the dome ports. Since the nodal point of the lens is going to shift with zoom factor, its position in relation to the dome will change. Not all housings are capable of controlling zoom lenses either. If it's the only lens you have, the best way to rig it would be to optimize it for the widest setting, and hope for the best if you end up zooming.

Beyond the technical issues, I feel that bringing a zoom lens underwater doesn't help you as much creatively as it might on land. If you encountered very different subjects on one dive; i.e., a 400-foot shipwreck, then sharks, then some diver portraits, then humpback whales, then the zoom might help. In reality, Elvis is about as likely to show up as all of those subjects in one dive. Whatever changes you make with a wide-angle zoom can usually be achieved by moving yourself in relation to the subject. It wouldn't be a big mistake to use a zoom, but personally I think the trade-offs make it not worth the trouble.

DIGITAL WIDE-ANGLE

Remember all those great wide-angle lenses you had with your housed film camera? Thanks to the 1.6X factor, they're just not wide enough anymore. To play in the same league as a film SLR, about the only workable prime lens would be a 14mm. This would give you the 35mm equivalent of around 22mm, which is acceptable. The only alternative (right now) would be Nikon's new 12- 24mm DX lens; although zoom lenses are not ideal, it's probably the best choice at this point. The new 10.5mm DX Fisheye presents some interesting possibilities too, functioning like the 16mm Fisheye in 35mm.

A huge number of housings have appeared for the "mid-line" digital cameras (Nikon Coolpix, Canon Powershot etc.) These cameras provide pretty good bang for your buck, and may be something you already own. The only major problem with them is their built-in zoom lenses, which are not wide enough, and don't do true macro. The solution has been supplementary optics, such as wide converters and close-up lenses. Depending on the manufacturer, these optics can be attached directly to the camera, or are an integral part of the housing. I haven't tried or tested any of these combinations, but I can make an educated guess about the results. They won't be as good as SLR's or DSLR's with prime lenses, but are probably very acceptable. For many beginners these days, these kinds of set-ups will be their entry point into u/w photography.

(Olympus PT-015 housing with wide-angle converter)

LENS CHOICES FOR MACRO

True macro lenses are really the only choice in this arena. For Nikon users, this means the 60mm, 105mm, and occasionally the 200mm. 3rd-party macro lenses will work fine as well. The 200mm will force a fair amount of water between you and the subject, so it really is used only in special situations. The Nikon 70-180Micro is an interesting lens, but may create some problems with housings. Some (but not all) manufacturers make ports that allow you to work the zoom function on it. It's also a fairly slow lens, which might make your viewfinder image a bit harder to see. Just as with wide-angle zooms, I'm not sure the trade-offs justify the added expense and hassle, but there are people using it.

For most people, the only choice to make is between the 60mm and 105mm. Both work beautifully, and have their own strengths and weaknesses. I use the Nikkor 105mm almost exclusively; I like having some working distance from subjects, especially when shooting at 1:1 or close to it. The Nikkor 60mm focuses down to 1:1, but there will be very little space in front of your port, which can make lighting difficult. On the other hand, the 60mm works far better for "fish portrait" size subjects.

(Horned Nudibranch, Nikkor 105mm/2.8Micro)

People use extension tubes and teleconverters with these lenses as well; about the only concern is making sure your focus/aperture controls still work with the extra hardware in place. Most housings can be outfitted to achieve this.

DIGITAL MACRO

Just as it does with photography on land, DSLR shines in the macro realm. You have the added 1.6X magnification, making for many choices in subjects that would be more difficult with housed film SLR's. Most u/w macro is done with 100% strobe, so you could get immediate results and adjust lighting etc. If you were setting up a DSLR tomorrow, I would recommend something like the Nikon 60mm. It would give you a good range of magnification, without introducing too much water between you and the subject. As mentioned, the compact digital cameras can be outfitted with close-up lenses to provide true macro capability.

AF OR MF?

Whether or not you use autofocus will probably be determined by what you're accustomed to using on dry land. Whether with AF or MF, the limited light levels underwater present a challenge. When shooting macro, almost everyone uses some kind of small modeling light attached to the housing. With AF it is basically mandatory, unless you enjoy the sensation of your lens racking back and forth for the whole dive. Even with MF, which I use all the time, the modeling light makes life much easier. On night dives, it usually becomes your primary light.

(Light & Motion housing with flat port & modeling light)

About the only side effect is that some subjects will be spooked by having a light shining in their face. Then again, some fish are curious about divers and lights, and will come closer to investigate. One of the few times I've been attacked underwater was when an Ocean Triggerfish decided he didn't like my modeling light, and assaulted my housing. Ah, the sacrifices we make for the cause...

For wide angle, I highly recommend not using autofocus. One of the odd elements of shooting wide-angle u/w is that a "virtual image" is created by the dome optics. This virtual image is closer than the actual subject, often in the 12-16" focus range of your lens. This means that the range of focus adjustment is quite small, and doesn't need to be changed that often. You still want to have the capability, since at times you will rack focus in as close as your lens/dome port allows. With wide- angle, AF can mean time wasted waiting for the camera to find focus when it probably didn't need much adjustment.

THE FUTURE IS 1'S AND 0'S

For reasons of expense and personal needs, I'm not in a big hurry to make a move into digital all that soon. In general however, the future for digital underwater is very promising, and is definitely the path that all the manufacturers are taking. The Digital Debate is covered ad nauseum elsewhere, so I'll just touch on a few specific issues with using digital underwater.

(Ikelite housing for Canon G3/G5)

It is generally acknowledged that for wide-angle, digital creates problems when the sun is part of the image. When using upward angles to put water in the background, a sunburst is often a desired component. For whatever reasons, digital struggles with these high-contrast situations, creating ugly banding and other artifacts. This has also been my experience with scanned wide-angle shots that include a sunburst. Reports indicate that the problem is more severe with cheaper digital cameras. This is a serious deficiency that hopefully will be overcome in the future. I've read of a couple of pro shooters who use digital for macro, but film for wide-angle because of this problem. As a friend of mine put it, there are truckloads of PhD's working in digital imaging right now, so it is very likely that this type of snafu will get sorted out eventually. .

The scarcity of appropriately wide lenses for digital is a drag, but probably a short-term problem. A new generation of DSLR's with (hopefully) full-frame sensors would eliminate it completely, of course. In the meantime, digital folks will have fewer options than the film buffs.

A clear advantage of digital u/w is the learning curve with wide-angle exposure. Instead of bracketing exposures and finding out the results a day (or week) later, ambient/strobe balances can be adjusted immediately. I think in the long run, one would want to bracket anyway, and make your final choice later. Personally, I can't imagine trying to look at a tiny LCD display and make editing decisions at 120 feet with limited air, but to each their own. An even bigger benefit is having more than 36 exposures on a dive. With absolutely no ability to change film underwater, the only way in the past was to carry multiple complete rigs. David Doubilet (Nat Geo) carries six or seven--or should I say, his assistants do. Having more shots is probably what I envy the most in DSLR's.

Some of the major players in u/w (Ikelite, Sea & Sea) have released strobes specifically for use with digital cameras. The only real difference is the ability to recognize some of the new circuitry and extended functions, like pre-flash etc. Quite a few older strobes will not work at all with digital cameras; in some cases they can be upgraded. There are currently some serious compatibility issues between certain digital cameras and strobes, especially in their ability to do TTL flash exposure. For example, the Fuji FinePix S2 Pro has full TTL capability with Nikon-ready strobes; the Nikon D100 and D1X do not. These problems will undoubtedly be solved in the future, but you should be careful that the camera/strobe combination you choose is actually going to work the way you want it to.

The major u/w manufacturers: http://www.seaandsea.com/ http://www.usanexus.com/ http://www.subal.com/ http://www.ikelite.com/ http://www.ulcs.com http://www.aquatica.ca/ http://www.nikonusa.com/ http://www.olympusamerica.com/ http://www.uwimaging.com/

Some u/w photo shops: http://www.absea.net/ http://www.marinecamera.com/ http://www.backscatter.com/ http://www.optiquatics.com/ http://www.seaoptics.com/ http://www.subaquaticcamera.com/

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