Olympus C-8080 Camera,
Underwater Housings, Ports and Wide-Angle
Lens.
Olympus
PT-023 Housing
for C-8080wz
Materials: clear polycarbonate
housing, red polycarbonate control knobs, Ni-plated brass control
shafts, Fluorite tempered glass lens port, Anodised Al lens ring
& sync connector cap, Stainless steel buckles, Silicone main
O-ring, NBR LCD hood.
Dimensions /mm: 181w, 188h,
200d. Weight: 1475g , excluding
LCD hood, lens cap & strap.
Kit includes: Wrist lanyard,
grease, Silica gel, O-ring remover, ballast weight, LCD hood,
lens cap, sync connector cap. |
 |
|
Bulkhead flash connector:
The metal version of the Olympus flash connector requires maintenance
even if an external flash system is never used. Remove the cap
or plug frequently and apply silicone grease to the screw thread
before reassembly. Failure to carry out this procedure may result
in seizure of the screw thread due to salt water corrosion. Attempting
to remove the connector blanking cap or sync-cable plug by force
will rip the bulkhead connector from the housing and may cause
irreparable damage. |
 |
Olympus PT-023 Housing
and C-8080 Camera
Test Pictures using Standard
Port
Internal Flash:
Standard Port, Full Wide, ISO 50, aperture as indicated. |
|
The Diffuser-box of the PT-023 housing gives the best internal-flash
underwater performance (flatness of illumination) seen by the
author to date. The light-trap design is good and there are no
signs of light leakage into the port. Note however, that the
flash output is very low, and the pictures above were taken at
close range in perfectly clear water. In conditions of moderate
visibility, backscatter is likely to be a problem, and an external
flash unit is (as always) strongly recommended. |
External flash, corner detail vs aperture:
Standard Port, Full Wide, ISO 50, Ikelite DS-125 flash with 4100.5
TTL slave sensor, aperture as indicated. Corner detail image
is full size (same resolution as original). |
Radial Correction (removal of pincushion distortion and
chromatic aberration):
Same photograph as immediately above, corrected using Panorama
Tools. |
|
PanoTools
Radial Correction
Coefficients |
 |
The chromatic aberration visible in the uncorrected pictures
is almost entirely due to the air-water boundary and is unavoidable
when using a lens with 75° coverage behind a flat port. The
effect will be reduced at longer focal length settings of the
zoom lens.
Radial correction allows complete elimination of chromatic aberration
and pincushion distortion. This will be beneficial if large prints
are required, but is not essential for small album photographs. |
PPO-05
Wide Port and WCON-08D Conversion Lens
PPO-05 Wide Port:
For use with CLA-8 bayonet adapter and WCON-08D wide converter
lens.
Depth Rating: 40m. 
Double O-ring seals.
Underwater photographs will exhibit noticeable optical distortion
(but pictures taken in air are not affected). Software optical
correction is recommended. See test pictures for details.
Materials: Fluorite tempered
glass optical port with anti-reflection coating. Clear polycarbonate
body, Silicone O-rings, Other parts: ABS, NBR, red polycarbonate.
Dimensions: Max dia 156mm,
overall length 90mm. Weight:
600g, excluding lens cap.
Supplied accessory: Grease,
O-ring remover, lens cap.
WCON-08D Converter Lens:
Magnification: 0.8x.
Coverage at full wide in air: 88° (35mm equiv: 22.4mm) |
Optical Data*
Lens System
(zoom setting = full wide) |
35mm equiv.
focal length |
Coverage
in air |
Coverage UW
(flat port) |
|
Standard lens. |
28mm |
75° |
54° |
|
Std. lens + WCON-08D |
22.4mm |
88° |
62.5° |
|
* Angle of coverage
figures are nominal, i.e., on picture diagonal when lens is focused
at infinity. |
|
PPO-05 Wide Port and WCON-08D
Lens
Test Pictures
Distance, camera to test card: 3m. Zoom setting:
Full wide. Aperture: f/5.6. ISO: 50.
Light source: Mixed daylight and Ikelite DS-125 with 4100.5
slave sensor.
(The white measuring stick attached to the bottom of the test
card is 1m long). |
Close-up, corner detail vs aperture:
PPO-05 wide port, WCON-08 wide lens, Full wide, ISO 50, Ikelite
DS-125 with 4100.5 slave sensor, aperture as indicated. |
Radial Correction (removal of pincushion distortion and
chromatic aberration):
Same photograph as immediately above, corrected using Panorama
Tools. |
|
PanoTools
Radial Correction
Coefficients: |
 |
|
The addition of the wide conversion lens gives the C-8080 an
effective 35mm equivalent minimum focal length of 22.4mm. This
gives a nominal angle of coverage of 88° in air and 62.5°
underwater. The use of such a wide angle lens behind a flat port
underwater results in a degree of pincushion distortion and chromatic
aberration which will be noticeable even in small album prints.
Hence, for underwater photography, software optical correction
is strongly recommended. Correction will not be needed if the
port is used merely for water protection, e.g., for surface water-sports
photography. |
Ikelite
Housing for Olympus C-8080
|
Ikelite 6130.80 Housing and Olympus
C-8080 Camera
Test Pictures
Standard Port (54°):
Zoom setting: Full wide. Aperture: f/2.8. ISO: 50.
Light source: Mixed daylight and Ikelite DS-125 with diffuser.
(The white measuring stick attached to the bottom of the test
card is 1m long). |
Standard port. Image geometry,
and corner detail vs aperture:
Standard Port, Full Wide, ISO 50, Ikelite DS-125 flash with diffuser,
aperture as indicated. Corner detail image is full size (same
resolution as original). |
Radial Correction (removal of pincushion distortion and
chromatic aberration):
Same photograph as immediately above, corrected using Panorama
Tools. |
|
PanoTools
Radial Correction
Coefficients
(for flat port,
full-wide zoom) |
|
Discussion:
The use of a flat air-water boundary always introduces some pincushion
distortion and chromatic aberration (colour fringing in off-centre
detail), and these effects worsen as the angle of coverage of
the camera lens increases. The uncorrected photographs above
demonstrate these effects in the worst case, i.e. with the lens
at its most wide-angle setting, which corresponds to a coverage
in air of 75° (35mm equivalent focal length = 28mm). The
pincushion distortion is less than expected, being partially
offset by barrel distortion of the lens, and is not sufficient
to require correction except when photographing subjects with
obvious straight lines and right-angles. Chromatic aberration
will however be noticeable in large prints and displays with
significant edge detail if the full-wide zoom setting is used.
Fortunately, the RGB separation in the camera is accomplished
with very well-behaved filters, resulting in a perfectly apochromatic
system if the user is prepared to take the trouble to apply software
radial correction to the pictures produced. If radial correction
is applied, the camera will give exhibition quality prints of
up to about 22.7 x 17" (i.e., 3264 x 2448 pixels at 144
pixels/inch). Note incidentally, that the radial correction for
the Ikelite standard port is exactly the same as for the camera
in the Olympus PT-023 housing with standard port. |
Dome
Port for Ikelite
C-8080 housing.
 Optical data: Port material:
Acrylic, nD=1.492. Inside radius:
3", 76.2mm. Nominal thickness: 0.218", 5.537mm. |
Optical Data*
Lens System
(zoom setting = full wide) |
35mm equiv.
focal length |
Coverage
in air |
Coverage
UW |
|
Standard lens. Flat port. |
28mm |
75° |
54° |
|
Std. lens, Dome port |
76° |
|
With WCON-08D, dome port |
22.4mm |
88° |
88° |
* Angle of coverage
figures are nominal, i.e., on picture diagonal when lens is focused
at infinity.
With dome port, some coverage is lost in practice underwater
due to lens extension, but optical distortion due to the port
is eliminated in wide-angle photography.
Flat port is recommended for macro-photography, due to strong
de-magnifying effect of dome port underwater. |
|
Dome Port: Test Pictures
Dome Port and WCON-08D (88°
wide-angle):
Full Wide, ISO 50, Ikelite DS-125 flash with diffuser, aperture
as indicated. |
|
Softness of corner detail at f/2.8 is due to curvature of field.
This effect will be less apparent at greater lens to subject
distances. |
Radial Correction (removal of barrel distortion and chromatic
aberration):
Same photograph as immediately above, corrected using Panorama
Tools. |
|
PanoTools
Radial Correction
Coefficients
(for DP with WCON-08D,
full-wide zoom). |
 |
Dome Port without converter lens
(76° wide-angle):
Full Wide, ISO 50, Ikelite DS-125 flash with diffuser, aperture
as indicated. |
The Ikelite dome port for the 6130.80 C-8080 housing is intended
primarily for use with the WCON-08D wide-converter lens, but
can be used without it. In this case, slight corner vignetting
may occur at the full wide zoom setting. Vignetting may be eliminated
by zooming in slightly, or by cropping the final image; or, for
preference, by applying radial correction for barrel distortion.
Radial Correction:
Same photograph as immediately above, corrected using PanoTools. |
|
PanoTools
Radial Correction
Coefficients
(for dome port,
full-wide zoom). |
 |
Comparison of Ikelite and Olympus
C-8080 housings.
|
|
Ikelite 6130.80 |
Olympus PT-023 |
|
Depth rating |
60m |
40m |
|
Use in rough conditions |
Yes |
No
(port mountings too delicate) |
|
Includes tray |
Yes |
No
(but too bulky for use without) |
|
Use internal flash |
No |
Yes (standard port only) |
|
TTL flash converter |
Supplied as standard |
Optional, HeinrichsWeikamp |
|
Supermacro mode with flash |
using Ikelite DS-series SubStrobe |
FL-20 + PFL-01*
FL-36 + PFL-E01
HeinrichsWeikamp converter |
|
Slave triggering** |
Not recommended |
Yes |
|
Accessory shoe. |
No |
Yes |
* TTL flash is possible with the
Olympus FL-20 flash and PFL-01 housing, but this flash system
is too low-powered for wide-angle UW photography and has no focusing
light.
** Slave triggering requires the
internal flash to be swiched on; in which case supermacro mode
will be unavailable. Since neither of the housings can be fitted
with an external macro lens (and there is no room for an internal
macro lens either), supermacro mode with flash is essential if
the user is to realise the full capabilities of the C-8080 camera. |
|
UW coverage (full wide) |
Ikelite 6130.80 |
Olympus PT-023 |
|
Standard port: |
54° |
54° |
|
PPO-05 + WCON-08D |
- |
62.5° * |
|
Dome port: |
76° |
- |
|
Dome port + WCON-08D |
88° |
- |
|
Needs CLA-8 to mount WCON |
No** |
Yes |
* The PPO-05 Flat port with WCON-08D
converter gives pronounced chromatic aberration and pincushion
distortion underwater. Consequently it unsuitable for large prints
and displays unless software radial correction is used.
When the WCON-08D wide converter is used with the PT-023 and
the PPO-05 port; the port must be opened and the CLA-8 unscrewed
before the camera can be removed from the housing. Changing batteries
and memory cards aboard an open boat may be difficult.
** The WCON-08D is held inside the
Ikelite dome port assembly and the CLA-8 adapter tube is not
required. Hence the camera can be removed from the housing without
disturbing the port setup. |
D. W. Knight © Cameras Underwater 2004. |
TTL
hot-shoe (Olympus protocol).
Filter thread M138 x 1.5
Removable diffuser-box allows internal flash to be used with
standard port.
Standard port fits Ikelite 4.2" push-fit UWCC filter #6441.43
B/G.
Pop-up flash cannot be used..
