Wide-angle
experiments with the Olympus
Mju 410 Camera and Ikelite 6138.4 housing
The tests described here were carried out in order to determine
the performance of the Olympus m410
camera when used with an underwater wide-angle conversion lens,
and also to investigate the feasibility of fitting an M67 adapter
ring to the front of Ikelite housings for small digital stills
cameras (many of which did not have supplementary lens provision
in 2004 when the investigation was carried out). The design issue
here is that many users want to be able to use the camera internal
flash, and so the provision of a permanent M67 filter ring (which
blocks the flash) is undesirable. A removable lens adapter is
therefore indicated, provided that the optical performance of
the camera and wide-angle lens combination is satisfactory.
For the purpose of the lens tests, the M67 lensholder ring from
an Epoque lens-mount adapter was bolted to an Ultralight AD-SS
YS-mount strobe adapter to make a lensholder which could be mounted
on a ball-joint arm. In this case, the ball-arm was mounted on
the top accessory shoe of the Ikelite housing. A black rubber
light-baffle (cut from an old tyre inner-tube) was fitted around
the housing port to prevent light from the camera internal flash
from leaking into the back of the wide-angle lens. The hole in
the baffle was cut approximately 2mm smaller than the port diameter,
to make a stretch fit and cause the baffle to adopt the shape
of a funnel. Lenses were tested with the back element pressed
into contact with the housing lens port; although, since the
camera coverage is well within the capabilities of each of the
lenses tried, a gap of a few mm would have been tolerable. The
light-source for the tests (not shown) was an Ikelite Substrobe
DS-125, slave-triggered from the camera internal flash by means
of an Ikelite EV-controller #4100.6. |
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Results, given below, show that the Ikelite housing and m410 camera gives excellent results
with all of the commonly available M67 wide-angle lenses. A slight
excess of illumination in the upper right quadrant of each photograph
indicates that the internal flash should be blocked in the forward
direction for best results in practice. Use of the internal flash
for illumination (rather than for slave triggering) is impossible
when a wide-angle lens is fitted. None of the photographs exhibit
any signs of flare, indicating that the port light trap in the
Ikelite housing works perfectly despite the highly reflective
finish on the camera lens barrel.. |
Test Conditions:
Camera zoom setting: 5.8mm
(35mm equiv: 35mm) = full wide
Aperture: f/3.1 (obtained
from EXIF data, same for all shots).
Focusing: Camera AF, normal
mode.
Light source: Ikelite DS-125
(positioned above camera) with 4100.6 EV controller .
Flash triggering: Slave from
camera internal flash. |
Post script:
The findings above were communicated to Ikelite, and resulted
in the manufacture of the lens adapters shown below. Newer housings
have a groove around the port, to give positive registration
for the lens adapter retaining screws. |
Ikelite Lens Adapters
 For Ikelite digital
stills housings with 55.6mm (2+3/16") diameter port.
 #9306.81
mounts M67 (67mm) screw fit lenses from Epoque or INON . Also
mounts M67 UWCC filters.
#9306.80
mounts INON AD bayonet lenses.
 Removable flash
blanking plate prevents exposure hot-spots and deflects flash
backwards for pickup by slave sensor.
 Camera built-in
flash is usually blocked by an external wide-angle lens. Use
of an external flash system or natural lighting is assumed. |
9306.80 - INON AD Bayonet
Shown with Inon UWL-015AD wide lens. |
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9306.81 - M67
Shown with Inon UWL-100 wide lens. |
 |
Text and photographs by D W Knight,
© Cameras Underwater 2004.
Production adapter photographs © Ikelite Underwater Systems
inc. 2004. |
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Magnification:
0.56x
Max. depth:
60m
