Introduction
This document explains how to use the Aquamir Digital Slave Strobe and Housing model PTS-120N. Using a slave strobe will improve your pictures by moving the light source away from the camera. The housing is waterproof and can be operated to a depth of 60 metres (200 feet).

This manual contains essential information as well as tips on how to obtain good results. Misunderstanding of how to prepare and use underwater equipment can lead to permanent failure, so please keep this manual for future reference and read it carefully before using the strobe and housing.

PTS-120N Package Contents
Underwater housing UW-120N
Digital Slave Strobe SS-120N
Diffuser holder
Diffusers #1, #2 and #3
Spare back-door O-ring
O-ring remover
Silicone Grease
Spare pad for auto-sensor x3

Housing Specifications
Model No: UW-120N
Compatible Strobe: Digital Slave SS-120N.
Depth Rating : 60 metres
Function Switches can be fully controlled except for Flash Trigger Override Switch (which should be set to ' AUTO')
Materials : Polycarbonate, stainless steel
Mounting system: YS-mount (Sea & Sea type) or ¼” x 20 (tripod size) screw (mounting fork is removable with screwdriver).
Dimensions /mm: 47d x97.5w x104.5h.
Weight: 200g

To open the housing (fig. A)
a. Lift the security lock
b. Rotate the Dial Lock clockwise
c. Open the rear cover.

To close the housing (Fig. B)
a. Engage the rear cover with the Dial Lock.
b. Rotate the Dial Lock anti-clockwise
c. Engage the security lock.

The PTS-120N is supplied with a diffuser holder which clips on to the front of the housing, and three diffusers which increase in optical density in order #1, #2 and #3. The diffuser holder is also equipped with receptacles for commercially available fibre-optic trigger cables, such as those made by Sea & Sea and Inon (not supplied). Eyelets on the front housing, the diffuser holder, and the diffusers allow the parts to be tied together to prevent accidental loss while working underwater. Use thin Nylon cord or fishing line, and allow sufficient length so that the diffusers can be removed and re-inserted for different lighting effects. Check that the retaining cords are in good condition when preparing the housing for use.

Operating Tips
In clear water and bright conditions, such as an outdoor swimming pool or shallow water with a white sandy bottom, the slave sensor may be overloaded. In this case, slave triggering with the bare housing may be unreliable. The diffuser holder acts as a sunshade for the slave sensor. Better still, it allows a fibre-optic trigger cable to be used. Fibre optic cables usually come with Velcro tape, which obscures the internal flash of the camera except for collection of light by the fibre-optic itself. Blocking the camera flash improves lighting by reducing direct (specular) reflections from the photographic subject.
Diffusers increase the effective area of a light source. This helps to reduce specular reflections and reduces the contrast of the image (softens the lighting), making it easier to produce a well-exposed photograph. Diffusers also increase the angle of coverage of a strobe. The disadvantage of a diffuser is that it reduces the overall brightness of the flash. Use of a diffuser is recommended in most situations, provided that the brightness is sufficient for the chosen camera settings.

Care and Maintenance
Do not use or store the housing at temperatures above 60°C (140°F).

Never use industrial solvents (alcohol, 111-trichloroethane, petrol, etc.) or paint thinners to clean the housing. Use only water and mild detergent.

After using the PTS-120N is salt water, do not open the housing immediately. With the strobe still inside, rinse the housing in fresh water and then immerse it in fresh water for at least 30 minutes to dissolve any salt deposits. Dry the outside of the housing with a soft cloth as far as is possible, and be sure to remove any trapped water droplets by detaching and drying the diffuser holder and the diffusers. When opening the housing, do so in such a way that water drops in the O-ring channel fall out of the housing. Do not allow water drops to fall onto the strobe inside; and especially, do not allow water to get into the switches and other openings.

Dry the housing thoroughly and store it in a well ventilated area away from direct sunlight.

Never try to dry an underwater housing by placing it on a radiator or using a hair-dryer. Temperatures above 60°C can easily be obtained, and may cause permanent damage.
Never try to dry the housing by placing it in direct sunlight. Clear plastic can act as a lens, focusing sunlight and causing heat damage.

O-rings change shape permanently when compressed for long periods, so store the housing with the back door open. O-rings also degrade slowly due to the action of UV light, so store the housing in the dark (e.g., in a drawer) to obtain maximum O-ring life. Do not put heavy objects on top of the housing when it is in storage, and keep it clean.

Store the strobe separately from the underwater housing. This will prevent the auto-sensor pad from becoming permanently crushed, helping to maintain its light-trapping ability.

Mounting the Strobe Housing

The housing is supplied fitted with a mounting fork of the type introduced by Sea & Sea some years ago (known as a YS-mount). Lighting arms with the YS-mount lug are made by several manufacturers, including Fisheye, 10Bar, Epoque, Sea & Sea, Ultralight and TLC.

The fixing bolt has an M8 thread and is interchangeable with the M8 stainless-steel hand-bolts used by other manufacturers. Do not over-tighten the fixing bolt; the mounting fork is meant to slip, so that the lighting angle can be adjusted. Put a tiny amount of silicone grease on the fixing bolt thread from time to time, to keep it running smoothly.

The PTS-120N strobe and housing is lightweight and can be mounted on inexpensive flex arms or Loc-Line arms without risk of sagging, even when supported in air.

In trigger mode 1, the slave strobe fires on the first flash.
In trigger mode 2, the slave strobe fires on the second flash.
In trigger mode 3, the slave strobe fires on the third flash.

To determine the correct setting for the trigger mode switch, perform a synchronisation test as follows:

Place the digital camera and the slave strobe face to face separated by a distance of about 1 metre.

Set the trigger override switch on the back of the slave strobe to the “auto” position.

Now take three flash pictures of the slave strobe with the trigger mode switch set in positions 1, 2 , and 3 respectively. Make sure the ready light on the slave strobe is lit before taking a picture.

The picture which is overexposed (bleached white) in the area of the flash window has been taken with the correct setting of the trigger mode switch.

Note: The number of pre-flashes may change when you change camera modes. Carry out the synchronisation test in all the modes you intend to use when taking actual photographs (e.g., underwater mode).

Some cameras may vary the number of pre-flashes used depending on the lighting conditions. If you think that this may be happening, you can carry out a quick synchronisation test at any time to see if a different setting of the trigger mode switch is needed.

Settings for Fully Automatic Digital Cameras
1) Set the camera flash mode to “Auto Flash”, “Forced Flash” or “Slow Flash”
2) Cancel the red-eye reduction function and choose “Slave Flash” (no pre-flash) mode if available.
3) Set the trigger mode switch of the slave strobe according to the synchronisation test described above.
4) Take some test pictures and adjust the output control switch of the slave strobe to get the best exposure. If the picture is too dark, increase the slave flash output. If the picture is still too dark at maximum output, move the slave strobe closer to the subject. If the picture highlights are bleached, reduce the slave flash output. If the picture is still over-exposed at minimum output, move the slave strobe away from the subject.

Settings for Digital Cameras with Manual Mode
1) Set the camera to “Manual Exposure” mode.
2) Set the camera ISO light sensitivity to 100, 200, or 400.
3) Set the lens aperture to f/2.8 or close to this value.
4) Set the camera flash mode to “Auto Flash”, “Forced Flash” or “Slow Flash”.
5) Turn off any red-eye reduction function and choose “Slave Flash” (no pre-flash) mode if available.
6) Set the slave strobe trigger mode switch to 1, 2, or 3 according to the synchronisation test described earlier.
7) Take some test pictures and adjust the output control switch of the slave strobe to get the best exposure. If the picture is too dark at maximum output, increase the ISO light sensitivity of the camera (or apply EV compensation) or move the slave strobe strobe closer to the subject. If the picture has bleached highlights at minimum output, decrease the ISO light sensitivity (or apply EV compensation), reduce the size of the aperture (set a higher f-number), or move the slave strobe away from the subject.

Note: If you use a high ISO light sensitivity value you may find that your pictures are noisy (grainy). If you use a wide aperture (low f-number) you may find that your pictures have very little depth of field (the zone of sharpest focus will be narrow). Experiment with the camera settings to obtain the best compromise for your purposes. Macro photographs are usually best when a small aperture (high f-number) is used.

Trigger Override Switch
The trigger override switch should normally be left in the "Auto” position. In that case, the slave strobe may also be triggered by other camera users in the vicinity. To prevent spurious triggering, move the trigger override switch to the “Push on / off” position. The slave strobe will then only trigger while the switch button is being pressed.
Note that the trigger override feature is not available when the slave strobe is installed in the UW-120N underwater housing. Choose the “Auto” position when closing the housing. Spurious triggering is unlikely to be a problem when working underwater.

Operating Tips
Wait for the green ready light to come on before taking a picture.

For close-up pictures, the camera's built-in flash may provide sufficient light on its own. Use of a slave strobe may then cause over-exposure. If over-exposure occurs you can do one of the following:
a) Switch off the slave strobe.
b) Move the slave strobe away from the subject.
c) For underwater working: Use a fibre-optic trigger cable and block the light from the camera's built-in flash.

The slave strobe is triggered by direct or reflected light from the camera's built-in flash. If the light received by the slave sensor is too weak, or is swamped by strong ambient light, triggering might not occur. Use of a fibre-optic cable can solve this problem when working underwater.

When the slave strobe is not in use, move the trigger mode switch to the “Test / Off” position to conserve the batteries.