Underwater photography can be as rewarding as it is challenging. Once the realm of professionals and determined enthusiasts willing to spend thousands of dollars on specialized and esoteric equipment, this hobby is now available to the rest of us thanks to modern developments in inexpensive but capable digital systems.
Updated 2007
When light travels from a less-dense medium like air to a more-dense medium like water, the rays are refracted or bent towards the normal or perpendicular of the surface between the two mediums. In crude terms, light going from air to water will tend to be straightened, while light going from water to air will tend to be ... um ... crookeded. Confused yet ? Take a look at the figure below.
( Tautogolabrus adspesus )
In this figure, you can see the light rays traveling from an object in the water to your eyes, neglecting the effect of the flat glass lens of your mask. The blue lines trace the actual path of the light rays through the water and into the air, or conversely, through the air into the water - the direction really doesn't matter. As you can see, the rays are bent toward the perpendicular of the surface on the water side, and away from it on the air side.
The red lines trace the continuation of the light rays on the air-side as if there was no water. Your brain uses the angles on the air-side to combine the images from both eyes into one, and also to calculate distance and size. There is no way for your brain to compensate for, or even be aware of, the bending of the light rays at the air-water interface, and thus the image that is constructed is wrong. Skipping a lot of complicated mathematics, the "virtual image" that your brain constructs from the composite view of both eyes is about 7% smaller and 33% closer than the real image in the water. Hence, the old adage that things look about 25% bigger underwater. Incidentally, the figures here are not mathematically precise, but they are fairly representative of the actual geometry.
Below is essentially the same figure, drawn out instead for a camera lens. The big difference for the camera is that it has only one "eye" and therefore no need to reconcile two slightly different views into one, as we humans do. Hence, the camera does not see a virtual image underwater.* While I'm talking about housed cameras here, the same analysis holds for true underwater cameras and lenses as well.
* Not quite true - see below.
The problem for a camera underwater is that because of refraction, it sees a greatly narrowed slice of the world, or a reduced field of view. Referring to the figure above, at the given
distance, you would be able to capture the entire image in air ( red lines, ) but in water you can only capture the part contained within the blue lines. In order to capture the entire image, it would be necessary to increase the distance to the subject - generally not a good option underwater, especially in our water ! Fortunately, this problem can be solved optically.
Right: A typical point-and shoot camera housing with a flat lens port.
Above is a camera mounted behind a dome port - a spherical section of glass or plastic centered on the camera lens iris. Light rays pass through a dome port with no refraction, allowing the lens to see underwater the same scene that it would see in air. A dome port like
this allows you to get much closer to your subject, which minimizes problems with murky water, and also allows better use of artificial lighting. This makes it useful for underwater photography under any conditions, and essential under typical North Atlantic conditions. However, a dome port is only as good as the lens behind it, so the use of a good wide-angle camera lens is essential.
Right: A typical SLR housing with a large dome port.
A drawback of any dome port, and especially smaller ones, is that the focal plane of the image is shifted inwards, creating a virtual image as little as 12 inches in front of the camera. Some wide-angle lenses can cope with this unaided, while others require accessory lenses called diopters to allow proper focus. This is not a problem for SLR cameras, but is not possible with most point-and shoots. In fact, most point-and shoot cameras behave very badly behind a dome port, since the 12-24" range typically falls between normal and macro focusing modes.
For point-and-shoot cameras a better solution is to use an accessory wide-angle lens, also useable with SLRs. This is a watertight lens that mounts externally to the camera housing. Such a lens can have an even greater effect than a dome port, without the focusing problems that a dome introduces. As with a dome, actual results will depend on the lens used. The figures shown are representative of a 35mm equivalent lens, typical of many modern point-and shoot cameras. An SLR would likely use a much wider lens - 10-20 mm is not uncommon, although expensive.
Drawbacks of a wide-angle lens include cost, handling, and fragility. Usually, such a lens must be attached ( or at least "burped" ) underwater to remove any air bubbles between itself and the port. Most external underwater lenses us a standard 67mm photographic filter thread - not the most robust or easy to use means of attachment. For the ultimate wide-angle performance, a dome port can be used with a wide-angle lens.
The downside of such wide-angle optics is that the resulting pictures tend to be distorted. This is especially obvious in scenes with a lot of straight vertical or horizontal lines. For example, look at the picture above, part of Herb Segars' superb portfolio of underwater photography. The first thing you might notice is that the barrel of the gun is curved, as is the anchor line. The distortion becomes more pronounced near the edges of the picture, especially in the corners. If you look more closely, you will also notice an overall distortion of perspective, commonly known as a "fish-eye" effect, where the center of the scene bulges toward you, and the edges fall away. This is so common in underwater photography that it is simply accepted.
Thus, extreme wide-angle lenses render rather odd photographs. But what is better, an odd photo, or none at all ? That is often the choice we have when the viz is not great.
Although it appears clear, water actually absorbs light at a much greater rate than air. Not only this, but it absorbs different colors at different rates. Reds are absorbed the most, while blues and greens are absorbed the least. Therefore everything looks green. But not as green as it should. This is because our brains can do a limited amount of color-correction, tuning out the greenness of what we see, and also because under low-light conditions our vision switches from color to black and white. In black and white vision, our eyes are most sensitive to greens ( a happy accident for divers, ) although we see them as grays.
The spectral absorption of water. Note the peak in energy in the blue-green range.
A camera, on the other hand, will faithfully record every bit of green that it sees, yielding results that are at first startling, like the green tank picture above. To capture true colors at depth, an artificial light source is needed, either in the form of a flash or a steady light. However, such a light source will inherently be of very limited power ( compared to the sun, ) and will therefore have very limited range. As the figure above indicates, 45% of the light energy is lost at a range of just one meter. This is just as true horizontally for artificial light as it is vertically for sunlight. In order for artificial lighting to be useful, it must be used at short range. This again raises the usefulness of the wide-angle optics described above, which allow larger scenes to be captured at shorter distances.
Photography is all about light. Good lighting is the single most important factor in getting good pictures. After that, technique, experience, and artistic composition are second, and fancy expensive equipment is a distant third.
Unlike photo equipment, light is generally free, during the day anyway. For good results, you usually want to collect as much of it as possible for every picture. This is the job of your camera's lens. The lens is the most important part of a camera, and it is ironic how manufacturers of SLR systems with interchangeable lenses generally sell kits with fancy expensive bodies ( lots of buttons, etc ) and cheap lenses. Even more ironic, much low-end photography is done with disposable cameras that have no lens at all ! Whether you use a point-and-shoot, a digital, or an SLR, make sure your camera has a good lens on it. Secondarily, shutter speed also affects your light-collecting ability. Better cameras have controllable shutters, while point-and-shoots are usually fixed at around 1/100 second.
As I said, on land during the day there is usually plenty of nice bright white light from the sun. Underwater is a different story. Light is much more greatly attenuated by water than by air. Not only that, but different colors are lost at different rates, or depths, the thing that is important to us divers. With a bright sun burning overhead in the tropics, you can get pretty good natural color balance down to about 30 or 40 ft. Below that, everything starts to turn blue, as the red light is filtered out by the water above. Your eyes are capable of adjusting to different color balances, so that scenes will appear normal to you, but your camera will see everything as it really is - blue. The deeper you go, the more color is lost, until eventually everything is more or less gray. This is aggravated when the sun is low in the sky, and less light penetrates the surface. Colors are also filtered out horizontally, which is why long shots always turn blue, even in shallow water.
That's the situation in the bright sunny crystal-clear tropics. The situation is different around here. The waters of the North Atlantic are seldom clear, more often soupy green. Forget about colors, at offshore diving depths of 60 ft or more, often so little light penetrates that your camera is lucky to see anything at all. Obviously, this can be a major stumbling block to photography.
The solution is to bring your own light with you, in the form of a strobe or flash. As on land, these have a very limited range, and even less in the water. Flash photography underwater is limited in range to about 8 ft at the extreme, 4-6 ft commonly. Another problem with flash photography underwater is backscatter - the snowstorm effect caused by illuminated particles suspended in the water between the lens and the subject. Backscatter is minimized by moving the light source away from the lens, which is the reason why underwater strobes are mounted on long arms.
The other solution to the light problem is to simply gather as much ambient light as possible, using a wide aperture lens and longer shutter speed, as well as possibly faster film. Better cameras, both film and digital, will give you access to a world of ambient-light photography that is simply not possible with a budget camera having a fixed shutter and small aperture.
In either case, a wide-angle lens will be essential to capture larger subjects underwater. On land, to shoot a larger subject, you can simply back away from it. Underwater this is not effective, as the intervening water will affect both the colors and the clarity of the shot. You may get away with it on occasion in the tropics, but with the limited visibility of the North Atlantic, your subject will often disappear into the haze if you back away even a few yards! A dome port, wide-angle, or "water correcting" lens on the camera housing, as well as a good wide-angle lens on the camera itself, will allow you to capture larger subjects at ranges that will result in good photographs. A wide-angle lens will also correct for the refractive properties of water as compared to air, which reduces the field of view of a camera in water.
The sad fact for North Atlantic photographers is that most of the time conditions are simply not good enough for any kind of photography. Bring your camera on every trip, so you don't miss that rare day that is extra clear. Given the early morning schedules of most area dive boats, I usually use the first dive of the day to scout the location, without the camera. If conditions are good, I take the camera on the second dive, when the sun is high and the light is best.
When attempting ambient light shots, try to get below the subject and shoot up at it, silhouetting against the bright water's surface. Shooting up or out from inside a dark hole can also yield nice results. To capture larger scenes, brace the camera against a solid object for very long shutter times. Manually firing a strobe during a long exposure can freeze foreground details, such as fish.
References on Underwater PhotographyMost books on u/w photography deal strictly with the tropics. Many are fairly technical, and go into a great deal of detail describing what is today essentially obsolete equipment, while others are little more than photo albums. I've yet to find a book on underwater photography that I would consider really useful, which is part of my motivation in writing these pages. For a great beginner's guide to photography in general ( but not underwater, ) pick up a copy of Michael Langford's 35mm Handbook.
Having acquired all your nice expensive equipment, you may want to insure it against damage and flooding. Alright, perhaps not a cheap film camera, but a high-end housed 35mm, digital, or video camera certainly deserves the protection. On the other hand, with proper care and maintenance, and attention to detail when sealing it up, a modern camera housing is extremely unlikely to leak.
NiMH batteries + salt water = one really nasty corrosive mess. Regular old alkalines are not nearly as destructive when you get them wet. What does this mean? Use NiMH batteries in the camera inside the housing, but use alkalines inside your strobes, so that if the battery compartment does flood, you can just rinse it out with fresh water and maybe lemon juice. The result of a wet NiMH battery will eat away the metal contacts of the battery compartment so fast that by the time you can do anything about it, it's too late. Alkaline batteries have plenty of oomph to drive a strobe, although not a camera. If your camera housing floods, the battery type won't really matter, since the salt water will destroy the camera all by itself.
Underwater, digital cameras have a number of advantages over film cameras. Probably the greatest is that you can see the picture you just took. While the preview screen on the back of the camera is small, it is enough to let you know if you got the shot, should try again, or not bother, and makes exposure bracketing much less necessary. You can learn more technique in one dive with a digital camera than in a whole season with film.
Another advantage is that you can delete bad shots right away. This allows you to shoot many more shots per dive, and significantly raises your percentage of "keepers". Memory cards for digital cameras have become quite large and inexpensive, so that you can easily have 100 shots or more for every dive, compared to 24-36 for a film camera. The CCD sensor that is the heart of a digital camera also has better low-light capabilities than most film.
Most zoom lenses on digital cameras have excellent close-focus settings. Underwater, this gives them on-demand macro capabilities, unlike most conventional underwater cameras which require special lenses to be installed before-hand, and then used throughout the entire dive. The digital camera's LCD viewer makes macro composition easy, so that with a single camera and lens you can shoot everything from tiny shrimps to humpback whales, all on the same dive !
Shutter lag used to be a problem with digital photography, but modern cameras are very nearly as fast as film. Most of the remaining lag is due to exposure calculation and autofocus - something that film cameras are just as prone to. Preset exposure and focus to get best performance when necessary - just like a film camera.
Remember - the camera you don't have with you isn't going to take any pictures - good or bad !
Pictured above is my own system. This consists of an Ikelite housing for the Canon A630 camera, with the Ikelite wide-angle lens, and dual strobes and spotting/video lights. There are a number of additions and modifications for New Jersey diving. Since every time I take this thing out I get questioned about it, I will describe each piece individually in detail:
The camera is a Canon PowerShot A630. This is a superb little camera that is also great for knocking around topside. It has a reasonably wide fast lens with a good zoom range, and sports a 2 inch pivoting LCD on the back. It has an 8 MP sensor, with good low-light capabilities and focusing, and program modes from full-auto to completely manual. It also shoots surprisingly good video. Power is 4 standard AA batteries that seem to last forever, storage is SD: a 2GB card will hold hundreds of stills, or about 15 minutes of best-quality video. This camera is a bargain at under $200. It has a near-identical big brother, the A640, but I could find nothing about it that justified the extra price for what I planned to do with it. More on digital cameras below.
Canon even makes a clear plastic waterproof housing for this camera, which is small and light, relatively inexpensive, and easy to use. However, although it is rated to 130 feet, I would consider it more of a "splash" housing - good for rain, boating, and around the pool, but not really for diving. I stopped diving with it after the third time I found drops of water inside. Still a useful thing to have though, especially after the "real" housing got bolted into a huge heavy lighting rig that you could never use out of the water.
Shown is the Ikelite housing for the A630/A640. This is a very well-designed and solidly-made housing, rated to 200 feet, yet still reasonably small. The polycarbonate construction lets you see the camera inside, so there is no guessing what button does what. All camera controls are accessible, even including one which is of no use at all inside the housing! The housing comes with a flat glass lens port that is threaded for an external accessory lens.
Some minor modifications were made for local conditions:
The wide angle lens is also from Ikelite, it roughly doubles the field of view. The camera must actually be zoomed just a bit to avoid vignetting; I usually don't bother. The lens mounts solidly to the port, yet still clears bubbles with no difficulty. I tied a tether around the lens body and attached it to the handle, just in case.
The Ikelite lens is actually a rebranded Epoque, and of good quality. An optical coating on the front glass quickly succumbed to salt water, and was rubbed-off with automotive buffing compound. On a lens like this, that was probably an anti-flare coating, and I don't see that being much of a problem underwater. The lens is also usable out of the water, where it behaves like a fisheye.
The handle is from my old Ikelite housing; it is otherwise available as a separate item, either single or dual. Obviously, the dual handle like mine is needed for a dual strobe setup. I use the 3/8" threaded hardware, rather than the quick-release. I think it is stronger and more suited to local conditions, and in any case, I don't want anything that might come apart in the water.
I replaced the stock plastic base with a home-made PVC buoyancy collar that reduces the in-water weight to a manageable two or three pounds. Out of the water weight is almost 20 pounds. The collar has a socket mount on the bottom for a camera support, either a tripod or monopod. I actually have a tripod that was custom made by a friend, but you could simply sacrifice a cheap tripod for underwater use. A simple PVC monopod is easier to use. My own design breaks down for easy carriage, and even features a tilt and swivel head. the collar also allows the whole package to sit upright when out of the water.
A standard Jersey "hi-lo" lanyard is attached to the handle at the left side. This allows me to have the camera firmly attached to me at all times. In fact, I usually jump in with it rather than have it handed down. I do this with all my things, and have not lost a piece of gear in years. If the camera will clearly be of no use, the lanyard can also be used to tie it down near the anchor line, so as not to have to lug it around.
The lighting setup consists of two Ikelite DS-50 underwater strobes, inherited from my previous setup. These are small but powerful for their size, and run on convenient AA batteries. A single one is really inadequate for local conditions, and even two do not fully cover the field of view of the wide-angle lens. Ikelite makes bigger strobes that would undoubtedly work better, but they are much more expensive. I seldom use the strobes underwater anyway, as they are limited in range to about eight feet, and I often want to shoot further.
The strobes are triggered by the camera's internal flash via slave sensors. One has an automatic TTL sensor, the other has a manual sensor; newer models actually have better electronics built-in. Both strobes also have a manual "full-blast" mode, which I find most useful in dark murky New Jersey conditions: make as much light as possible, and dial back the exposure in the camera if necessary.
In addition to the strobes, each arm also carries a regular light. These are Ikelite's Mini-C model, with accessory mounting brackets. The Mini-C throws an very bright pencil beam that is useful for aiming the attached strobe. To make them more useful for shooting video as well, I rough-sanded the bezels, giving them a more diffused even light. Each Mini-C also has a brass clip attached, should it ever be needed.
The Ikelite arms are simple and strong, and easy to adjust in the water. The plastic eyebolts that hold the arm assembly together were replaced with stainless steel after they broke. The only other modification to the arms was to add through-bolts to the ends to prevent the arms from slipping out of the eyebolts should they loosen. These are visible in the photo below.
Above is the whole apparatus folded up for traveling, ie: lugging it around in the water. The arms are folded across the top and bungied down to make a compact solid package that is easy to carry and hand up to the boat. The lens is protected by a wetsuit-padded hard plastic cover made from an old light bezel. The split rings allow multiple accessories to be clipped on to the main unit, such as a sunshade for the rear LCD. Diagonally across the back of the housing, just visible, is an elastic back strap that holds the back of the housing in place without closing the latches. This makes for easy storage without crushing the o-ring. The whole thing actually fits inside a large plastic toolbox for transport without disassembly.
All together, this represents about $2000 worth of equipment, most of which I already had. Many people are amazed to see me take such a setup in the water around here. This complete rig represents quite a bit of thought and development, and with the modifications and additions mentioned here, it is robust and well suited to New Jersey diving.
There was one alternative that I did consider, briefly. That would have been to house my Canon 20D SLR. That would have cost several times as much, depending on just how far I wanted to go with it. And without an expensive new lens, diopters, and a big fragile dome port, the housed SLR would not even be as useful as the little point-and-shoot. In any case, the end result would have been much bigger and bulkier, and more delicate and expensive, such that I probably wouldn't want to take it in the water here, and that would defeat the whole purpose !
One of the first pictures I ever took with this setup. Not bad, I think.
The little Canon housing has proved useful in situations where the huge Ikelite would be difficult or impossible to take along, such as shore diving. In shallow water, no extra lighting is needed. Positively buoyant, it hangs up instead of down when clipped-off. Note the home-made port cover.
Surprise! A dogfish in the Shark River, taken with the Canon housing.
Don't be afraid to spend too much on your lighting system, because unlike the camera / housing combination, your strobe lights will not soon become obsolete. ( The same foes for the wide-angle lens. ) If you invest in the new Ikelite digital strobes and wireless TTL slave sensors, you can transplant them onto any future camera system you get, digital or film, and get many years of use from them. I prefer two small strobes to one big one of equal cost. With two strobes you have many more options: you can widen the area of illumination for larger scenes, overlap them for more intense spot lighting, or shut one or the other off for special effects. Use of dual strobes also avoids the strong dark shadows that are inherent with single strobe use. These underwater slave strobes could also be used topside with a suitable strobe tray for the camera. As I said earlier, your lighting system is at least as important as the camera itself, so if you have extra cash, spend it here.
In conjunction with the accessory aiming lights, strobe aiming is a snap. The co-axial aiming lights throw a bright spot on the subject that is washed-out when the strobe fires. These small but powerful halogen lights also light night scenes for the camera's autofocus system, and are bright enough that no other dive light is necessary.
The aiming lights alone, without the strobes. Instead of aiming the strobes side-by-side, here they are aimed near and far, to try to illuminate a longer shot.
One problem that I have noticed when using this lighting system under local conditions is that the TTL exposure setting on the strobes consistently gives under-exposures, and they should be set on manual or "full-blast" for best effect. This is not a defect in the equipment, but rather a defect in the water, which absorbs so much of the light on its way to and from the subject that even the best metering systems are fooled. The camera's exposure system and flash are designed to shoot through nice clear air, while the strobe is calibrated for relatively clear tropical waters, where in fact the TTL setting works just fine.
Ikelite has an enormous range of stock housings for a great many digital, video, and film cameras. For local use, I would add a dual handle for strobe mounting. Note how on my setup all small accessories are tethered to the main unit, which is in turn tethered to me with the lanyard. This is good practice for all dive gear.
Digital camera technology is progressing at a phenomenal rate. Much like computers, prices steadily fall, while features and performance improve. When setting up an underwater digital photography system, first make sure you have the very best and latest top-of-the-line digital camera available. Don't buy a housing for a camera that is already old, or you will find yourself stuck with an expensive combination that is already obsolete, or very soon will be. Get a new camera first, then get a housing for it.
There are 4 inter-related factors in digital camera design:
Skimp on any one of these, and the whole package suffers. Don't put too much weight on electronic features and do-dads ("extra buttons") - you probably won't ever use them anyway. Fortunately, digital cameras have improved tremendously, while dropping in price, and there is no need to skimp on anything any more.
My recommendations ( 2007 ) would be:
Modern cameras have excellent battery life. Avoid models that use proprietary batteries - generic rechargeables improve steadily every year. For very cold conditions, keep a set of disposable Lithium cells handy, and in an emergency, you can even use regular old alkalines from 7-11 or your flashlight.
For memory, stick with SD or CF, whatever the camera uses; it makes little difference. Avoid oddball formats like Sony Memory Stick - it stunk when they invented it, and it still stinks. Memory and batteries have both become inexpensive in recent years.
Digital camera lenses are pretty generic nowadays. They are all in the range of 35-140 mm ( 35mm equivalent. ) For underwater use, wider is better, but the choices are limited, as the manufacturers find it easier to build and market long zooms instead.
My strong preference in point-and-shoot cameras is the Canon A-series, in particular the A630. This is an 8MP model with a large bright "VariAngle" screen that pops out and pivots - very useful out of the water. It is a bargain, and can be found for under $200, but you will also need memory and batteries, not included.
Canon's A-series cameras are simply terrific. They are powered by either 2 or 4 AA cells, and use common SD memory. They have a range of features and shooting modes from full auto to full manual for any situation, and are fast and easy to use. Many of them have a "Custom" program mode which will save a combination of camera settings for instant access. So with the twist of a dial, you can put in all your underwater settings at once !
For some excellent reviews and background information on digital cameras, take a look at Steve's DigiCams, the Digital Camera Resource, and Digital Photography Review. These guys pull no punches; printed magazines are far less useful. If none of this makes sense to you, here is an excellent glossary of digital camera terms.
Once you make up your mind what to buy, the best place to buy a digital camera ( and a lot of other things ) is B&H in New York City ( mail order ). Ikelite products are available through most dive shops, and also B&H and LeisurePro ( ask - many things are not in the catalogs ). Their prices may not be absolute rock-bottom in the entire country, but unlike many mail-order discount houses, neither of these vendors will screw you. Items are either in stock and shipped promptly, or they will tell you the truth about the situation.
One of the great advantages of digital photography is the ease with which the resulting photos can be manipulated and improved later using your computer and an image editing program. Of course, you can also do this by scanning film prints or slides, but dealing directly with digital images is faster, easier, and virtually free.
Underwater photos ( film or digital ) may suffer from the following problems:
With a digital image, all of these are easily corrected, within reason. As I said above, it is often possible to turn a poor shot into a usable one, and a good shot into a great one, using image editing software. My favorite program ( for PC ) is an inexpensive but highly capable package called Paintshop Pro. You can download a fully functional trial version from http://www.jasc.com. This program is small, fast, and easy to use, unlike the clumsy, difficult, and slow heavyweights from Adobe and Corel. Windows XP even comes with a serviceable if limited image editing program for free.
Paintshop allows you to correct all of the problems listed above, and many others. Color controls can directly adjust darkness, contrast, and color balance. There are filters to automatically sharpen, soften, and blur images, and tools to rotate, crop, and resize your images. In addition, Paintshop contains a host of digital painting tools. Almost all the images in this website, whether scanned or digital, were edited in Paintshop v7.
For example, for the Ikelite housing image above, I initially photographed the subject against a white bed sheet, rotated it, and then digitally erased the background. The image was then cropped to emphasize the subject and resized it to fit the page layout here. Finally, the text labels and logo were added, to get the final product.
 Before |
 After |
On the more typical underwater photograph below, notice how the bluish cast has been removed, and the vibrant reds and deep blacks restored. Although you couldn't possibly see it here in these tiny examples, often a one-click application of the sharpen filter will bring out a great deal of eye-pleasing detail, such as the scales on the side of a fish. All of these things are easy to learn how to do.
 Before |
 After |
An even more radical example of what is possible: here Samantha is lost against a bright sky. Selectively lightening areas of the picture brings out the figure in the foreground.
 Before |
 After |
Probably the most common image manipulating sequence is Crop - Resize - Sharpen.
Almost all of the images in this website were manipulated in this way.
Another function that can be useful for underwater images is grayscale. Use this to turn an overly green image into a normal-looking black-and-white one when other color manipulations fail. Our eyes see black-and-white under low-light conditions, and this looks much more natural in a photo than shades of green.
Do you think this is cheating? How do you think the pros get those great pictures that you see in the dive magazines? In fact, they probably go to even greater lengths than I have described here. And you can do all this on your home computer.
The helicopter at Dutch Springs - ambient light.
By well-lit, what I mean is situations which fall within the normal range of your camera's exposure program. This is a combination of ISO (film) speed, shutter speed, and aperture which will result in capturing a desired image. On land, such situations occur all day long, but underwater they are rare. Clear shallow water with a bright sun shining overhead is the only environment in which your camera is likely to work unaided, as it would topside.
An unremarkable ambient light test shot, at a depth of about 100 ft.
Click for 3-megapixel original. Note the loss of colors, even close-up.
Flash would bring out all the hidden colors.
In deeper water or under less-bright conditions, ambient light may be augmented with flash. Flash has a number of drawbacks when used with auto-programmed exposure. Most cameras have a fixed flash sync shutter speed of around 1/90 second in any automatic exposure mode. This is very fast for underwater shooting, and will cause the camera to capture little if any of the available ambient light. Hence, any distant background will be extremely dark or even black, although the subject should be properly lit by the flash.
An indirect problem with flash photography under such circumstances is focus. Unfortunately, auto-focus does not work nearly as well in a housing behind a port underwater as it does up above in air. If your camera has a fast lens ( f/2.8 or better ) the auto-exposure program will naturally make use of it, and open up to the maximum aperture. Such wide apertures have very little depth-of-field, and thus any error in focus is likely to ruin the shot. Compounding this, there is often little in an underwater scene for an autofocus system to "latch on to", and focus errors are common.
To increase your likelihood of success, use aperture-priority mode to manually stop down the lens to f/4.0 or so, and increase the ISO speed to 200-400 to compensate. Remember - it is possible and even easy to salvage a poorly exposed digital photo by "pushing" or "pulling" the exposure after the fact, but if the focus is off, there is no way to fix it ! Ironically, cheaper cameras with small-aperture lenses may be saved from these focus problems by depth-of-field.
Underwater strobe lights have a very limited effective range, four to eight feet at the outside. This limits you to shooting only subjects that are within flash range. Large subjects are typically not possible, owing to the restricted underwater field-of-view at the short distances involved.
Herb Segars is a master of underwater flash photography.
Sand is tricky stuff to shoot at with a flash, because it is usually so reflective that all you get in your picture is glare, especially at close range. Try turning the strobes slightly away from the subject, so the light falls indirectly, and use a diffuser.
All modern automatic cameras use an internal "program" to determine correct exposure settings. The inputs to this program are:
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A typical exposure program might include the following parameters:
| Aperture | Shutter | Film Speed |
| f/2.0 f/2.8 f/4.0 f/5.6 f/8.0 |
1/10 1/20 1/40 1/80 1/160 |
50 100 200 400 800 |
Each step in any column corresponds to a doubling or halving of the light-gathering capability. Obviously, a 1/20 shutter will gather twice as much light as a 1/40 shutter. Less obviously, an f/2.8 aperture will collect twice as much light as an f/4.0 aperture, while a film speed of 400 requires half as much light as a film speed of 200. Unlike a film camera, with a digital camera it is possible to alter film speed on the fly.
Changes in one column can be compensated for by opposite changes in other columns. Thus, the following exposures are all equivalent:
| Aperture | Shutter | Film Speed |
| f/4.0 f/5.6 f/4.0 f/2.8 |
1/4 0 1/40 1/20 1/80 |
200 400 100 200 |
The exposure program selects an aperture and shutter speed within its available ranges so that the resulting photograph is properly exposed. Unfortunately, these programs are designed for bright topside daylight, and typically will not produce good results when taken into the dim depths of the North Atlantic. In particular, most exposure programs simply refuse to use the longer shutter speeds necessary to make use of the limited ambient light. Although the camera hardware may be capable of very long exposure times, these are simply not included in the program. Instead, the program will most likely open up the aperture wide, select the slowest shutter that it can calculate, and signal an exposure error.
There are two problems with this. First and most obvious, the photo will be underexposed. Second, and more seriously, it will likely be out of focus. Compact cameras have no effective manual focus mechanism ( try using yours and see ) and most autofocus systems simply cannot cope with the low-light and low-contrast conditions underwater. As stated above, these focusing errors are compounded on better cameras with faster ( larger aperture ) lenses. The depth-of-field at f/2.0 for a typical high-end compact digital camera lens at typical underwater ranges is measured in inches ( see diagram above. ) If your autofocus system misses by two feet, the photo will be useless. Even if the autofocus is perfectly accurate, with such a tiny depth-of-field, most of a large subject is likely to be out of focus anyway.
The stern gun on the
R.P. Resor. Note how the muzzle is
in focus, while the rest of the image is not.
Most automatic cameras also have several semi-automatic modes, notably aperture priority and shutter priority. Using aperture priority, one could try to select a smaller aperture to lessen the focusing problems, but this would result in the camera underexposing everything, as the exposure program simply will not compensate enough with shutter speed. Shutter priority is useless, as the necessary slow shutter speeds are not made available. One could also attempt to compensate by increasing the film speed, but this results in unacceptably grainy results if taken to extreme.
Finally, one could resort to flash, but this has a number of drawbacks, which are discussed above. For wide angle photography, the default flash synch shutter speed will simply not allow the camera to collect enough ambient light for a proper exposure, and for larger subjects at longer ranges, underwater flash is useless, or even worse than useless.
| 1. ISO: 2. Aperture: 3. Shutter: 4. Flash: 6. Focus: 5. Zoom: |
200 - 400 f/2.8 - f/4.0 1/8" - 1/4" on / off normal / macro full wide |
The solution to all these problems is to go into the scary realm of fully manual photography. Forget what your camera's built-in light meter is saying, ignore the "shake" warning, and escape the limitations of the automatic program. At right is a good starting point for manual exposure underwater. Notice that it says Checklist. Print this out, and stick it inside your camera housing where you can see it.
Note that the aperture is set to a fairly small f/4.0, to assure good depth-of-field and lessen autofocus errors. This is compensated-for by boosting the film speed, and using very long shutter speeds, which are completely outside the automatic exposure program's useable range. For extremely long exposure times, it is useful to note that digital cameras do not suffer from color-altering "reciprocity failure" as do film cameras.
It is possible to hand-hold a 1/8 second shutter speed, but for any slower shutter speed, and for best results in general, the camera should be braced against a solid object or otherwise supported. This can be as simple as setting the camera down atop a tall object, or using a monopod. A monopod is like a one-legged tripod, in which you serve as the other two legs. An inexpensive, durable, lightweight, rust-free monopod can be built from PVC plumbing parts from the hardware store, and will vastly improve your photographic results.
One advantage of very long shutter speeds is that objects in motion, such as particulates in the water, tend to blur out of the picture, while fixed objects remain sharp. Unfortunately, this means that fish and other divers are likely not to come out, and divers with lights can completely ruin a shot. An advantage of fully manual mode is that the flash can be turned on without affecting the selected shutter speed, and can therefore be used for "fill." However, as the pictures below illustrate, this can often backfire.
Misuse of flash. In the shot on the left, the strobe illuminates particulates in the water,
known as backscatter, obscuring the subject. The anchor winch on the Sea Girt wreck.
Underwater, and especially under dark local conditions, images on the camera's preview screen will appear overly bright and even washed out. This does not mean that they are overexposed, but is rather just a trick of your own eye looking at that bright little screen. All pictures also look very clear and sharp on that little tiny screen, even when they are not.
Be sure to take multiple exposures, and "bracket" your shots. For each scene you wish to capture, take two or three shots at your base exposure setting, then two or three more with slightly different settings. This will typically mean starting with a shutter speed of 1/8 second, and then bracketing with 1/4 second and 1/16 second. Taking several shots at each setting guards against hand-shake and focus failures. After a number of shots during a dive, you may find that you can dispense with exposure bracketing and just use one particular setting, but continue to take multiple exposures for focus.
Except for the images that are grossly blurred or off-exposure, keep all the pictures you take until you get home and can judge them properly on your PC. It is much better to invest a few dollars in a big memory card than to ever use the delete button on the camera.
This subway car is 51 feet long and 9 feet wide, and the whole thing is in the frame.
My thanks to Herb Segars for saving me a lot of time and trouble working out manual camera settings.
For more on cold-water photography, try these links:
One day, when conditions were marginal for still photography, I put my little camera in video mode, just to see what it could do. Was I ever surprised at the result! Here is the first underwater video I ever shot:
This was originally shot at the highest quality settings that the camera has - 640x480 resolution, 30 frames per second. At this setting, I can get about 15 minutes on a $20 2GB memory card, which is about all you could do on one dive anyway. Between dives, I can empty the card into the computer, or switch cards if necessary. The camera offers no other controls - just start and stop - so shooting is pretty much a no-brainer.
You'll notice two things about the video above. The first is that it is unlit. I have no video lights that could possibly light up a scene as wide and deep as you see here, and no intention of spending thousands of dollars on such a setup. The obvious benefit of shooting natural light is that you do not trap yourself inside the small area that you can illuminate. Thus, I can capture a shipwreck in recognizable form, when otherwise I might have nothing but a lot of (well-lit) sea anemones.
The downside of this is the lack of color - most everything is green. The best solution to this problem can also be free - have a buddy pick out colorful details with his dive light. This would be a good use for an HID light. It is also possible to shoot strobe-lit stills in between videos.
The second thing you'll notice about the video is the slight distortion and "vignetting" or black corners that goes along with the use of the wide-angle lens. The ability to get closer to your subject, and lessen the amount of murk in your shot, is a worthwhile trade-off. The vignetting could be avoided by zooming the camera slightly inside the housing, but I think it is better to leave it full-wide and treat the problem later, in production.
When shooting video, it is important to hold the camera steady and move slowly. Don't forget to shoot lead-ins and lead outs for every scene - these can be removed later if not needed. Generally, you will shoot in one of three ways:
The last option is by far the most difficult, and can become very tiring for longer shots. Combinations of all three methods can give nice results, such as pan around 180 degrees, and then take off swimming. Don't be afraid to re-shoot something if you think it didn't come out - pixels are free.
This is where the real work begins. After shooting your video, you'll want to edit it into something presentable, with some kind of plot or sequence, titles, transitions, narration and soundtrack ( other than Darth Vader noises. ) Both Windows and Mac come with very basic video editing software built-in that you can start with.
I quickly outgrew Windows Movie Maker. Fortunately, all the major video consumer-level editing packages offer downloadable free trials. After some testing, I settled on Pinnacle Studio 11 Ultimate, which is packed with features, has the best interface of the programs I tested, and is reasonably free of hangs and crashes.
Pinnacle Studio 11
All video editing software seems to suffer from a steep learning curve and some program instability. To run reliably and smoothly, there are also steep hardware requirements. My year-old Dell laptop was only just adequate, even with 120GB hard drive, 1.66MHz dual processor CPU, 1GB memory, and 128MB video. After upgrading the disk to 250GB, and the memory to 2GB, and adding a USB2 external hard drive ( actually the old one in a new case ) the machine now does video very well.
One thing that is important when "rendering" video is to always render to a different physical disk than your software is running from; that is to say, a second hard drive. A USB2 drive is perfect for this; a large memory card will do in a pinch. This makes the process both faster and more reliable. Rendering directly to an optical disk is a good way to make coasters; render a disk image to a hard drive, and then burn it to CD or DVD once it is confirmed good.
When editing the video above, I have zoomed in slightly to reduce "vignetting" - the black corners caused by the wide-angle lens. I also pushed up the contrast, and tweaked the brightness as needed. You can also alter the hue to something less green if desired. For web use, I render to a "NTSC medium quality" Windows Media file. This results in a 320x240 display size, 3-4 MB per minute, which plays back smoothly over a cable-modem or DSL connection.
That's all I've learned about video so far, with my little "jackass" video camera.
I make no claim as to the accuracy, validity, or appropriateness of any information found in this website. I will not be responsible for the consequences of any action that is based upon information found here. Scuba diving is an adventure sport, and as always, you alone are responsible for your own safety and well being.
Copyright © 1996-2008 Rich Galiano
unless otherwise noted
