by J Floor Anthoni (2005)
The only camera manufacturer who seriously
tried to meet the needs of the underwater photographer is Nikon with its
series of Nikonos underwater and amphibic cameras. Their latest was the
Nikonos RS with through-the-lens reflex viewing and other important qualities.
It is not the intention of this underwater course to review commercially
available cameras and underwater housings, but the Nikonos cameras provide
us with examples of what to demand from any underwater camera and to understand
The Nikonos V appears to be the end of the non-SLR cameras with automatic
exposure but without automatic focusing. It is the end product of a long
period of experimentation and gradual improvement, and even in the era
of digital photography, still has its uses as it comes with very sharp
A 600-page detailed compendium of Nikon products on the web, in German.
Very thorough in both descriptions and specifications. It is complete as
well. All Nikonos gear is there.
history It took a very long time before the ideal underwater camera emerged.
It was not just the Nikon company who contributed to the development of
underwater cameras as others like provided high quality housings for the
Rolleimarin series of double reflex cameras. With these cameras, explorer-photographers
like Hans Hass laid the foundation for what any underwater photographer
needs to know, all of it included on this web site.
Here is a short chronology of events:
1949: Hans Hass develops in co-operation with the German company
Franke & Heidecke the famous Rolleimarin underwater housing for a double-lens
reflex Rollei 6x6cm camera. It became the most successful underwater camera
of its time, later replaced by the single-lens reflex (SLR) Hasselblad.
the Belgian inventor Jean de Wouters makes the CalypsoPhot for the dive
equipment manufacturer SOS. It becomes the first waterproof 35mm amphibic
camera with 35mm lens that can be used both above and under water. It came
on the market in 1961 with a 35mm and a 28mm lens, 1/20 to 1/1000s
1962-68: the Nikon camera company develops the CalypsoPhot further
with its original inventor and releases the Nikonos I, first in a long
line of 35mm amphibic cameras. The UW-Nikkor 28mm lens is the first correcting
for the air-water interface.
1968-75: the long reign of the Nikonos II with many improvements
but still without sprocketed film transport. A 28mm lens and a 15mm lens
become available. An 80mm lens is now available. First distance ring for
macro photography underwater and on land.
1975-80: The Nikonos III has many improvements like sprocketed film
transport and larger viewfinder, but remains essentially a mechanical camera
made from robust parts that keep working in harsh conditions.
1980-84: the Nikonos IV with TTL light metering in aperture priority,
strobe light control and a hinged back leaves many disappointed as the
old 15mm lens was incompatible, the shutter speed fixed for flash photography
and the housing prone to flooding.
1982: the famous UW-Nikkor 15 mm lens becomes available.
the Nikonos V with electronic TTL through the lens light metering and a
wide range of shutter speeds, receives an enthusiastic welcome. It also
controls and mixes the strobe light of the new strobe models SB102, 103
and 105 at all shutter speeds to 1/90. The Nikonos now has watertight exchangeable
lenses of 80, 50, 35, 28 and the famous15mm and is still today a good expedition
backup camera in case all else fails due to dust, dew, moisture or ice.
It can be fitted out with several Nikonos underwater strobes and strobes
made by other manufacturers. A large variety of accessories is available
from brackets and macro tubes to flash synchro cables.
1986: a sharp 20mm lens becomes available.
the Nikonos RS 35mm SLR autofocus autoexposure camera for depths to 100m,
with an extensive set of very high quality underwater lenses, sets the
standard. Although it was the camera everyone had been waiting for, it
was taken off the market in 1996 due to poor demand and internal restructuring
at Nikon Japan. In slow succession its lenses became available: 28mm, 50mm
macro, 13mm fisheye and 20-35mm zoom. Specialty lenses became available
from other manufacturers, notably from Germany. The SB104 strobe is the
most powerful on the market, designed for fisheye lenses.
Today in the age of computers and digital cameras, it is hard to imagine
that underwater cameras took such a long time to evolve from their basic
models. Even so, they do not match what the digital camera of the future
may offer. In today's digital cameras we already encounter an adequate
resolution and colour sensitivity, the ability to balance and filter colours,
and a seemingly inexhaustible storage cartridge for far more than 36 exposures.
And they have a long list of additional features. But most of these features
do not count underwater, where a basic camera is all one needs. Indeed
many digital cameras in their small housings fail the basic requirements
for underwater use, the subject of this chapter.
V Production of the Nikonos V has also stopped,
even though demand remains high as indicated by the second-hand trade.
It is the last of the non-SLR series and comes with a good set of lenses
from 80mm down to 15mm.
In its long reign of compatible amphibious cameras, Nikon has set a de-facto
standard for underwater strobes, now offered by many manufacturers. This
means that Nikonos cameras can successfully be matched with non-Nikon strobes
and other products. Here are the camera's main limitations:
non SLR: one views the subject through a viewfinder placed above
the camera but the lens is not in any way coupled to this viewer in order
to judge the point of focus. But it is a wide viewfinder suitable for the
80mm, 35mm and 28mm lenses. For wider lenses an additional viewer must
be mounted on the strobe type shoe on top of the viewfinder. No special
adaptations are needed to view with a dive mask on.
limited focal distance: the 35mm lens focuses down to 80cm above
water, which is 106cm under water (a range of 1-1.25 diopter). External
closeup lenses are needed to focus nearby.
magical 15mm lens: the UWNikor 15mm lens is a very sharp wide angle
lens, corrected for the air-water interface and able to focus closeup to
sharp macro: closeup photography with the 28mm and 35mm lenses using
distance rings, gives sharp results with good depth of field, better than
a 100mm macro lens could.
So what would one use this camera for as so many alternatives exist?
general photography: it is a robust camera with dependable light
metering and strobe control and a good tool where environmental conditions
are harsh, such as moisture and dust. It has always produced good action
shots of surfers. Note that the 35mm lens can produce a blue spot in the
photo, caused by sunlight reflecting on an internal lens. Keep direct sunlight
out of the lens.
macro camera: the 35mm and 28mm lenses used with fixed distance
rings and framers, still give the sharpest images with the most depth of
backup UW camera: we all hope that our main camera and strobe will
work flawlessly during our expensive holiday or even more expensive contractual
shoot. But what if it fails? Are you coming home with no shots at all?
As a backup camera the NikonosV can still take good photos and it is such
a small package (body + 35mm lens + Sea&Sea 16mm lens + distance rings)
as it uses the same strobes and brackets from your main camera. Make sure
how to work it and keep spare batteries handy.
RS When I switched from movie to still photography,
the Nikonos RS was just taken off the market, after only 5 years. Why?
Here is my interpretation of events:
expectation: underwater photographers knew it was coming and had
high expectations. They expected a camera like the NikonosV but with a
mirror-reflex system, while perhaps even using the available Nikonos lenses.
Because of this high expectation, disappointment had to be deep.
quality: Nikon's expectation was different as it was ready to make
the best underwater camera ever. The US Navy placed a large order, and
they required a camera that would work to 100m depth. So it became bulkier
and heavier. With hindsight, one can see that Nikon has indeed made no
compromises. They even developed new technology that would later be incorporated
in all their topside lenses.
price: the high price of this camera was its main disappointment.
Little did people realise that what they paid for is what they got. It
is caused by the gulf of difference between the professional who knows
that quality is what you pay for, and the amateur who thinks he would not
need such quality.
marketing: it could be argued that the people knowing least of the
potential of this camera, were found within Nikon Headquarters. Marketing
was weak, and never were the camera's qualities that really mattered, mentioned.
Salesmen didn't know and potential buyers did not get informed.
wrong sales network: here was a product for a very small niche market,
but Headquarters chose to market it through their normal worldwide distributors
and retailers of snappy cameras. It meant that really nobody knew how good
this camera was and how to sell it. It also meant a large markup to retail
price. This happened at the same time the Internet grew useful. This camera
should have been marketed over Internet and this would still be viable
today, witness sales from E-Bay (www.ebay.com).
slow release: a definite mistake was the slow release of essential
lenses. It took a long time before other lenses than the 28mm standard
lens became available, and all that time the camera was essentially unusable.
hysteria: a world-wide hysteria of disappointment spread like wildfire,
not helped by very little experience (and thus photos taken with it).
internal reorganisation: what few people remember was a major shake-out
happening between camera manufacturers in Japan. It all began with infringement
of US autofocus patents, and it ended with major internal reorganisations
within those companies. One of the decisions of the bright boys from Headquarters
was to axe the Nikonos RS, a decision that may be regretted in the long
term. Here was this vast investment in research and development, thrown
to waste. But who knows, one day a digital camera insert may be slipped
into an RS body, and make this R&D come to fruition again. (but digital
cameras use a CCD which is smaller than 24 x 36mm)
flooding: there were reports from flooded cameras, and these stood
out not because of it happening but of the capital involved and the perceived
risk. More about that in the tips and tricks
maintenance: this was a camera that could not be serviced by all
and sundry, mainly because it was almost impossible to guarantee to a depth
of 100m, which required test capabilities to 200m! So, sending it back
to a very few service centres was necessary. Nikon stipulated further that
the warranty would expire if not serviced preventatively every year at
a substantial cost, exacerbated by high freight costs (and agent's markups).
It never explained why, and with hindsight, this requirement could have
been relaxed. What people don't realise is that salt water sneakily corrodes
the bits that seem unessential, like the screws in the body that cannot
be rinsed. So periodic removal and replacement of such unimportant bits,
is actually very important. For myself, having Nikon's service department
behind me, gives me confidence in my equipment, knowing that whatever happens,
it can be fixed, and that my investment is protected. In the past three
years their service department in Japan has provided me with exceptional
service, professional skill and prompt delivery. How much is that worth
to you? A lot to me.
Let's now review the camera's features and what these mean to the
underwater photographer. The camera was conceived at the time of the f801
and its insert indeed resembles an F801 camera body, as does its bayonet
lens connection. But major modifications have been applied.
autofocus: having an autofocus camera rates as the most essential
feature to me. There is just no time to judge focus through a viewfinder
and turning knobs. Most opportunities last only for a fleeting fraction
of a second, but enough for the autofocus mechanism. For people with limited
eyesight, it is simply indispensable. Compared to a camera with manual
focus, it enhances your chances at least tenfold. But autofocus is a nuisance
on unmarked grey objects like dolphins, and in those cases a preset focal
distance works best. Autofocus can also be a nuisance in very tight macros.
The RS has extended this idea fourfold:
single shot: the camera fires one shot only when in focus and not
otherwise (focus priority). Important for most situations. When in focus
there is no delay.
continuous: the camera focus follows the subject as long as the
shutter button is half depressed, but will fire immediately as many shots
as long as the button is pressed down (shutter priority). Ideal for nervous
subjects moving within the depth of field range given by aperture settings.
Use this focus mode where the right moment is more important than precise
power (manual): The RS has a special rocker button to focus manually.
It also has two depressions: slow and fast. Manual focusing is important
for shooting dolphins and whales, inside caves and more. When autofocus
won't work due to light conditions or faint subjects.
freeze (preset): a very useful feature not normally found elsewhere.
The focus is preset and when a subject presents itself in focus, the shutter
releases. Ideal for supermacro photography where autofocusing is a nuisance.
It combines the benefits of auto and manual focus. Prepare the focal distance
by aiming at a rock, doing it manually or so, then turn the focusing system
to Freeze. Now focus by moving the camera forward while retaining composition.
Ideal for macro photography when everything moves through wave action.
autofocus lock: focus and keep the shutter release button half depressed.
Then compose and shoot. Most cameras have this feature but it is very important
fast shutter: the RS synchronises with a strobe at up to 1/125s.
This enhances opportunity significantly over a 1/60s speed.
aperture: the RS (I think) is the first camera that controls aperture
by an electric signal rather than by turning a ring on the lens. In underwater
cameras this normally requires a clumsy mechanism and a dial hidden somewhere
on the front of the housing or side of the lens. But on the RS it sits
as a large dial on top where it adds to simplicity of operation.
simple operation: the RS is the ultimate in simplicity with aperture
autoexposure only, precisely the most successful method under water. It
has large buttons which are easy to operate even with 5mm gloves on. In
the dark one blindly finds the right buttons and their settings show in
the lit status bar. All important settings are done by the right hand.
With the left hand over/under exposure is set.
large reflex viewer: the viewer is exceptionally large, extending
high above the housing, giving full view of the entire image and the status
bar underneath. Until you've had one of these viewers, you simply don't
know how important it is for success. Internally Nikon placed a large and
complicated prism with sharp optics. The viewfinder screen is also exceptionally
bright. But there is no ocular adjustment for near- or far-sightedness.
It is assumed that your dive mask does this.
status bar: the status bar or LCD readout under the viewfinder screen
shows autofocus status, auto exposure status, shutter time, aperture and
over/under exposure for manual control. The LCD is bright and easy to read,
allowing you to change settings while peering through the viewfinder. This
is particularly handy with wary objects where every movement invokes suspicion.
Note that when peering at dials, one needs to turn the camera and with
it the strobe, which altogether is a major movement.
matrix metering: matrix metering was already part of the F801 generation
of cameras, and this has been sold as an advantage. The camera indeed produces
quite good exposure metering but can be confused in unusual situations.
In manual mode when shutterspeed is selected manually, the exposure metering
reverts to spot metering.
exposure compensation: the RS has a separate dial for exposure compensation
to enable bracketing. But this alters both strobe and ambient light intensity.
To control each separately, one must revert to manual mode, reading over/under
exposure of ambient light from the status bar and using the exposure compensation
dial to control the strobe. It works indeed very well with the use of filters.
One can then apply colour without shadows, creating a very natural look
in mixed-light photography. The exposure compensation dial is not strictly
necessary if it can be done by changing the ISO setting but when using
a wide angle lens, is changed often.
rear-curtain flash: a slide switch sits as an afterthought inside
the back cover and cannot be operated from the outside. Rear-curtain flash
fires the strobe at the end of the exposure, which places the silhouette
of a moving fish behind its tail rather than in front of its nose. This
setting also allows aperture priority autoexposure to extend shutter time
beyond 1/30s. It is a refinement typically for underwater photographers
and it does not hurt to take this as the preferred mode as long as a tripod
is available. For macro photography the shutter speed is set manually to
manual or automatic ISO setting: so often the automatic DX sensor
fails (also on other cameras) and I prefer now to do this manually. It
is indispensable when pushing a film to a higher ASA rating or when preferring
slight over (negatives) or under exposure (slide)
remote shutter release: an additional 4-pin waterproof plug allows
one to connect a remote control through a 3m cable. It enables one to place
the camera on a (heavy) tripod for taking photos of shy creatures. The
remote control push button works like the one on the camera, focusing when
pressed halfway down and clicking the shutter when pressed fully. An LED
light provides feedback of the strobe's readiness. This is perhaps the
only camera in the world with such an option.
invisible features: this camera has a number of important features
that are not immediately evident.
strength: the camera is extremely strong and rugged, except for
the lens housing bayonet which from necessity had to remain relatively
thin. An exchangeable lens has two bayonets: one ties the housings together,
the other the lens to the internal camera body.
coating: the colour of this camera is grey not because the arts
department said so but because this is the hardest anodised coating one
can give aluminium. Aluminium does not rust because of a thin oxide skin.
Anodising can thicken this skin, also making it very hard.
lens coating: the lenses also have the hardest and most salt-resistant
coating ever made. So they should be long-lived. Nonetheless, after a dive,
rinse the camera and lens and then gently wipe the lens dry to prevent
materials choice: only the highest quality materials have been used
in making the underwater housings of camera and lenses.
sharpness: the UW Nikkor lenses are all sharp at their widest aperture,
thereby extending your opportunities in low light conditions.
round aperture: the aperture inside the UW Nikkor lenses have so
many lamella that they are effectively round, not triangular as in some
cheap cameras or hexagonal in more expensive cameras. This makes scatter
The above is indeed an awesome summary of the capabilities of the RS against
which you can weigh your own camera system. I hope that potential underwater
photographers read this first before buying a camera. We'll now look at
R-UW AF Nikkor 28mm f/2.8: the 28mm lens is the cheap option to
begin owning an RS. But it is a sharp lens. A true 28mm lens without distortion
or blue edges is a gem to possess even though this lens focuses down to
only 26cm (4 diopter). It has an 88mm screw thread for its lens cap and
any accessories. Note however that an 88mm filter must be mounted under
water or would otherwise be crushed while going down.
R-UW AF Zoom-Nikkor 20-35mm f/2.8: for many the work horse for its
zoom capability, even though it won't focus closer than 38cm (3 diopter)
but the 35mm gives very nice closeups at this distance. It has a large
R-UW AF Micro-Nikkor 50mm f/2.8: an awesome macro lens that focuses
down to 16cm (6 diopter) producing 1:1 enlargement. It can be used above
water because of its flat port, which is sometimes handy when taking photos
in and above rock pools. This lens is also excellent (the best) for aquarium
photography. It also has an 88mm screw thread for its lens cap or accessories.
An excellent lens for modelling.
R-UW AF Fisheye-Nikkor 13mm f/2.8: the super-wide angle lens is
also a 'macro' lens as it focuses down to 14cm (7 diopter). This allows
you to bring in a single image that which is very nearby and objects far
away. It is a very creative lens but also difficult to master. This lens
brings the ability to take reasonable photos in very dirty water of less
than 1m visibility but it has been designed with barrel distortion,
which can be eithervery creative or annoting.
Lenses supplied by other manufacturers: the Nikonos RS has inspired
others to make the best but all these efforts have been undone by Nikon's
fateful decision to discontinue the RS.
2x teleconverter: made by René Aumann (Germany), changes
the 50mm macro lens into a 100mm macro lens with magnification of 2:1.
An awesome tool to keep some distance between you and your subject and
to let strobe light in. Sharp but camera movement during the short period
of strobe light, becomes noticeable.Also takes a long time for auto-focusing
18mm rectilinear wide angle: made by René Aumann (Germany),
is a very sharp wide angle lens without barrel distortion. It has a large
port. A very beautiful addition to the RS range of lenses but also very
expensive. Perhaps your best choice for modelling and fashion under water.
f037625: with a correction lens behind, the Nikon Fisheye
13mm can be used above water. Edge to edge sharpness from foreground to
background, but on closer inspection, slight red edged, as can be expected
from a corrected underwater lens. Even lighting by SB104 strobe.
f040931: this 12mm aeolid nudibranch was photographed with
a 50mm macro lens and 2x teleconverter in wavy conditions using the Nikonos
RS Freeze focus ability.
For the more advanced user there are a number of gripes about the Nikonos
tray and brackets: the camera tray (on which the camera is mounted)
and its strobe brackets are not flexible and do not meet the demands of
the advanced underwater photographer.
knobs turning the wrong way: when you are placed blindfolded with
the RS in your hand and asked to increase the aperture number, which way
would you turn the knob? Which way for over and under exposure? And which
way for the shutter speed? Which way to move the rocker switch for focusing?
Well, they all seem to operate the wrong way. At least the camera is right-handed
with most important dials and the shutter release button where you expect
The Nikonos RS comes with a single-sided or a double sided
tray with a single or double part arm joined to the tray by a quick-release
mechanism. The arm is jointed by a double ball-joint which allows much
freedom. The whole setup is rather heavy and large.
The large and intuitive controls on the Nikonos RS makes
this camera 'love at first sight' for the advanced photographer. All important
controls on the right include the focus priority which is a new feature.
All lenses have a wide viewing window to read their distance settings,
which is also lit at night. Only the film counter, hardly seen here left
of the aperture dial, is hard to read even though it is lit at night and
has a magnifying window.
See also the tips and tricks chapter for
alternative brackets, fast lens caps and filter change, replacing sub-C
cell nicads in the battery pack, and more.
cameras At the time of writing, digital cameras are taking
the photographic world by storm, particularly that of snapshooters. These
cameras are in the pixel race, culminating in 6 million and later perhaps
more. But colours do not appear fully true as people's skins become smoothed
like baby skins. But the result is immediate and assisted by software which
is able to look at all pixels, results are often better than that obtained
from the analog negative film.
Digital cameras are good for learning how to take good photos because they
provide immediate feedback but many exhibit limitations for good underwater
photography. Sold in polycarbonate underwater housings, complete with strobes,
these cameras become disappointing. Why?
Let's first consider their advantages:
autofocus: the more expensive digital cameras can focus continuously
into macro range, solving one problem of macrophotography.
autoexposure: the quality of autoexposure depends on price and make
of camera but most now have exposure programmes for different situations
like landscape (average), sport (fast shutter), portrait (large aperture),
night (over expose), macro (small aperture), and so on. But for the professional
photographer who likes to makes his own (and better) settings, these programmes
are of little use. For instance, the camera cannot sense that a tripod
mixed flash fill: the camera controls flash light intensity very
well, able to produce perfect mixed light photos.
high depth of field: because the CCDs are usually small (6-24mm),
the focal distances of the lenses used are also small, which improves depth
of field considerably.
soft tone: digital images are usual poor in contrast which enables
them to store more f-stops in the limited signal space of 3-byte JPEG.
variable sensitivity: in order to match the analog camera's choice
of film speed, digital cameras either adjust sensitivity automatically
or allow the photographer to control simulated ASA film sensitivity settings.
In this manner the one camera has a range of virtual film types.
large zoom range: often because image resolution is less, digital
cameras come with an astonishing zoom range, but with poor wide angle capability.
large storage: digital cameras are usually able to store more than
36 exposures, depending on resolution and the size of its memory card.
display image: to be able to see the result immediately, is of considerable
advantage as it allows one to take immediate remedial action, which includes
reframing, zooming, different angle and of course improved lighting.
delete image: very important to save storage space and to allow
for a more exploratory way of taking photos.
immediate use: the camera can be connected to a computer or printer
and results used very shortly after taking the photo.
many options: cameras offer many other options such as sound recording,
movie clips, in-camera editing and so on.
But digital cameras also have their disadvantages:
shutter delay: the most annoying thing
about many digital cameras that there is a forced delay between pressing
the button and the moment the photo is taken, often taking 0.5-1.5 seconds!
This makes them unsuitable for situations where the moment is critical
such as sport photography, and even baby photography. Most underwater photos
are critical in this respect.
slow reset: whereas a classical camera
only needs to transport the film, a digital camera needs to write the image
to (slow) memory, which can take several seconds, depending on image size.
Thus a repetitive shot cannot be taken quickly.
red-eye pre-flash: red-eye pre-flash further delays the moment,
and on many cameras this cannot be disabled. Underwater it scares fish.
Turn it off for underwater photos.
display-based: the mode of taking photos
is to hold the camera at some distance and judge composition by the image
on the display, which has several disadvantages:
slow action: aiming the camera correctly, is much slower than when
viewing through the viewfinder.
missing detail: the small display cannot show as much detail as
a good viewfinder. One needs to have good eyesight to be able to view a
display close up as well as the subject further away. In a good viewfinder
both the image and the camera settings are seen at a similar distance,
requiring the eye to accommodate less. It is for instance difficult to
judge whether a subject is smiling or has its eyes closed.
movement: holding a camera at distance does not benefit from the
stability offered by one's head, resulting in much more movement unsharpness.
small image: even though the result is immediately viewable, the
display is so poor that one cannot fully judge either colour, contrast,
brightness or sharpness.
ambient light: the LCD screen is usually not bright enough in ambient
daylight, like not having a viewfinder at all.
complicated operation: changing the
settings on most digital cameras is very geeky (computer like) with dialog
windows, cursors and action buttons. It is not possible to do this blind-folded
or in darkess. People with poor eyesight need closeup lenses. By contrast,
the traditional camera has large dials and these can be set in complete
darkness (f-11 = 4 clicks away from fully clockwise, e.g.)
low power flash: small cameras cannot have big strobe capacitors
and their strobe light is therefore much less powerful than that from traditional
flash too close: the small strobe light is placed close to the lens,
which causes red-eye and underwater the worst of scatter. Only in very
tight macro photography can the internal strobe be used under water. In
all other circumstances it contributes to disappointing results.
no remote flash connector: most digital cameras are so self-contained
that they do not provide a connector for a remote flash. Many do not even
have a tripod screwhole. For underwater use, this is unacceptable.
poor remote strobe control: some digital
cameras can control an external strobe by sending pre-flashes containing
strobe setting information. But these are not always received, which introduces
a high degree of uncertainty in underwater mixed-light photography.
needs off-line storage: whereas the classical photographer works
with film cartridges stored in waterproof film cans, the digital photographer
needs to have enough flash cards or a laptop computer for offloading them.
lacking colour detail: digital still cameras have only one CCD with
which three coulours (RGB) are 'guessed' by alternating pixels, sensitive
in either R G or B. In smoothly changing grades of colour, this can be
seen as a smoothed-over effect or as bands. In dark areas it causes high
lacking detail: with 6 megapixels the digital camera comes close
to the classical 35mm camera (3000x2000) but modern films with modern lenses
do a little better (4500x3000 = 13.5 megapixels). One must be alert to
false claims and that the claimed number of pixels is not generated by
interpolation. Also the lens system must be sharp enough to justify it.
lenses not water-corrected: the digital camera is often housed in
a small underwater housing with a flat port, which limits the use of the
wide-angle part of the zoom lens. The lens is also not corrected for the
air-water interface, causing blue edges.
poor wide-angle performance: The wide
angle lens is very important underwater and underwater wet-mate
lens attachments (for wide angle use) are usually of poor quality.
For underwater photography the digital camera is certainly not a panacea,
and potential users must be aware of their shortcomings, many of which
preclude high quality underwater photography. The most important of these
have been marked in red in the summary above.