Ikelite DS51 User manual

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the event of a product update.
DS51 TTL Strobe
Product Number 4044.1

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About this Product
Thank you for your purchase of Ikelite equipment. Please read this
instruction manual completely before attempting to operate or dive
with this product. Please visit ikelite.com to register your product
to receive information on any updates or notices pertaining to your
equipment.
Included in the Box
• DS51 strobe
• Diffuser # 0561.2
• Bulkhead cap # 9104.5
• 1” Ball Mount # 4081.4 (Strobes produced after October 1, 2016)
• Silicone lubricant 1cc tube # 0184.1
• 2 year manufacturer warranty
Specifications
• Weight ....................................................0.6kg (1.3 lbs.) with
batteries
• Energy Rating ........................................50 watt-sec.
• Coverage Angle ....................................70° (80° with diffuser)
• Widest Angle Lens ................................28mm SLR
• Guide Number (ISO 100) feet ...............56 surface, 28 underwater
• Guide Number (ISO 100) meters ..........17 surface, 9 underwater
• Firing Modes ..........................................TTL/Auto, Full, 5 fractional
powers
• Color Temperature 5700°K
• Power Source ........................................4 AA-cell alkaline, NiCad,
or NiMH

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• Flashes ..................................................200 full power
• Recycle Time..........................................3.5 seconds (full power)
• Depth Rating ..........................................90m (300 feet)
• CE - Compliant with applicable EU directives
• Complies with FCC part 15, subpart B, Section 15.109 for Class “B”
Products
Overview of DS51 Features
• Mode switch features TTL/auto and manual exposure settings.
• Battery compartment accommodates four AA batteries: alkaline,
NiCad, or NiMH.
• Ready light indicates when strobe has recycled.
• Diffuser provides softer lighting, wider coverage angle and reduces
strobe output by one f-stop.

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Important Notices
»To prevent salt build-up and sticking controls, submerge the
strobe in clean, freshwater. Operate the knobs several times
each while underwater to ush out any residue.
»Do not use cleaning agents, spray lubricants, Rain-X, or
other solvents on strobe. Use of an incompatible chemical
compound can damage the plastic and o-rings, and may result
in leaking.
»The DS51 bulkhead connector is not waterproof and must
be capped when not connected to a cord or sensor. Using a
DS51 underwater with the bulkhead connector uncapped or
unconnected will cause the strobe to ood.
»The strobe is factory sealed; do not disassemble. Disassembly
will void your Ikelite DS51 limited warranty.
»Do not continuously re the strobe more than 15 times above
water in rapid succession. If this does happen, allow the
strobe to cool down for at least 10 minutes.
»Lithium-ion batteries are NOT recommended

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Contents
Product Registration 1
About this Product 2
Included in the Box 2
Specications 2
Overview of DS51 Features 3
Important Notices 4
Getting to Know Your Strobe 7
Mounting the Strobe 8
Ikelite Arm/Mounting System 8
Attaching a Sync Connector 9
Battery Compartment 10
Opening the Compartment 10
Opening the Compartment 10
Changing the Batteries 10
Battery Compartment - continued 11
Closing the Compartment 11
Compartment Flooding 12
Strobe Ready Light 13
Ready Light with TTL Housing 13
Ready Light with Remote Optical Slave Converter #4403 13
Mode Switch 14
OFF position 14
TTL/Auto Exposure Position 15
Manual Exposure Position 15
Strobe Diffuser 16
Using the Diffuser 16
Diffuser Installation and Removal 16
Maintenance 17

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Post-Dive 17
Cleaning, Travel and Storage 18
Troubleshooting 18
Photos are over-exposed (too light) 18
Photos are under-exposed (too dark) 19
Strobe will not re 19
Strobe will not re when using sync cord 21
Strobe will not re when using an optical sensor 21
Ready light does not come on 22
Limited Warranty 22
Service and Repairs 23
Contact Us 24

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Getting to Know Your Strobe
ikelite
SUBSTROBE
DS
51
ikelite
Knob Battery Door Mode Switch
Strobe Ready Light
Waterproof
Bulkhead
Cap
Bulkhead
Connector
Flashtube
Mount

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Mounting the Strobe
Ikelite Arm/Mounting System
The DS51 will accept several Ikelite strobe arms and mounts on the
underside of the strobe body. A 1-inch Ball Mount Mark II is included
which will allow attachment to 1-inch diameter ball arms from Ikelite,
TLC, Ultralight, Nauticam, and others. For further information, please
visit ikelite.com.
51
ikelite
SUBSTROBE
DS
4080.05 Compact Ball Arm
4081.4 1-inch Ball Mount
Mark II (Included)

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Attaching a Sync Connector
»A bulkhead cap or waterproof connector must be attached
to the strobe for waterproof operation. Never submerge the
strobe without either a bulkhead cap or compatible waterproof
connector attached.
1. Remove the bulkhead cap.
2. Lightly lubricate the connector O-ring. We recommend using only
Ikelite silicone lubricant to eliminate the possibility of swelling due to
incompatible compounds.
3. Line up the pins and receptacles and insert the Sync Cord Plug into
the bulkhead. The plug should slide easily into the bulkhead. If you
feel resistance, do not force it. Remove the plug and check
alignment.
Sync Cord Plug
Connector O-ring
Bulkhead
Waterproof
Bulkhead Cap
4. Rotate the knurled retaining ring until snug on the housing
bulkhead. Do not use pliers or tools to tighten the retaining ring.

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Battery Compartment
Opening the Compartment
Always turn the strobe to OFF before opening the battery door located
at the back of the strobe. To access the battery compartment, rotate
the knob counter-clockwise several times and gently pull the door
off. Tilt the rear portion of the strobe down while removing the battery
door to eliminate the possibility of water droplets falling into the battery
compartment after a dive. Do not remove the knob from the battery
door. The battery compartment is sealed separately from the main
electronics. Do not disassemble the strobe. Disassembly will void your
Ikelite limited warranty.
Opening the Compartment
Be aware of the position of the o-ring around the perimeter of the
battery door. Keep the o-ring and sealing surfaces clean.
Lubricant is not necessary for proper sealing of the battery door o-ring.
To extend its life, you can lightly lubricate the exposed part of the
door’s o-ring before storing.
Changing the Batteries
Install four AA-cell batteries: alkaline, NiCad, or NiMH. Refer to the “+”
and “ – “ markings in the battery compartment to help properly install
the batteries. If the batteries are installed incorrectly, it may damage
the strobe’s electronics. Always carry spare batteries; weak batteries
cause many camera and strobe problems. It’s time to replace the
batteries when the ready light remains dark for 15 seconds or longer
after a ash.
Note: It is possible to buy bad “new” batteries, so check the voltage
output with a meter. Lithium-ion batteries are not recommended due
to their effect on the strobe’s recycle time and the batteries’ thermal
switch characteristics.

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Battery Compartment - continued
Closing the Compartment
Check that the o-ring and sealing surfaces are clean. Make sure the
o-ring is back in its original position and free of any debris.
Lubricating the o-ring will NOT result in a better “seal” to the strobe
and is not necessary. Lubricant can be added before storage to help
extend the life of the o-ring. The o-ring is seated in the battery door
channel and does not need to be removed. Frequent removal of the
o-ring can increase the risk of dirt or debris getting into the o-ring
channel and causing a leak. If the o-ring needs to be removed, do
not use a screwdriver or other sharp instrument that may damage the
o-ring channel and result in a leak.
Replace the battery door. Make sure the door ts into the recess
around the battery compartment. Rotate the knob clockwise several
times and rmly hand-tighten to assure the proper o-ring seal;
otherwise, the battery compartment may leak. The o-ring seal is
visible through the battery door. Visually conrm that there is
a solid black line which indicates a seal all the way around the
door.
O-ring Seal: Note
solid black line
when properly
sealed against the
strobe body
Knob: Rotate
clockwise to tighten

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Compartment Flooding
The battery compartment is separate from the DS51 factory sealed
electronics. Should the battery compartment ood, ush the
compartment with fresh water and dry thoroughly. Determine the
cause of the ooding to the best of your ability. Send the DS51 and
other system components involved to Ikelite for inspection and testing
as soon as possible.
Often, divers nd themselves in remote locations for extended periods
without access to multiple strobes. If the strobe with the ooded
battery compartment is the only one available to you at the time and
you’re desperate to continue shooting, please follow these instructions
for a temporary x:
1. Air out and thoroughly dry the battery compartment with air from a
blow dryer or a SCUBA tank hose.
2. Wash out the battery compartment with alcohol. Repeat Step 1.
3. Replace all batteries after battery compartment ooding. Never
re-use batteries that have been wet. The water could create an
internal short circuit in the strobe at some later date, potentially
causing an explosion.
4. Reassemble with fresh batteries.
5. After returning from your trip, send the DS51 and other system
components to Ikelite for inspection and testing.

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Strobe Ready Light
The Ikelite DS51 Strobe features a ready light at the rear of the strobe
that glows red when the DS51 has recycled and is ready to re its
ash again. This recycling time should not exceed 15 seconds. If the
glow disappears for longer than 15 seconds between ashes, it may
be time for new batteries.
Ready Light with TTL Housing
When the DS51 is in TTL mode and connected to an Ikelite DSLR
housing, the strobe ready light will glow green for approximately two
seconds to indicate a correct exposure. If no green light appears,
check the image for possible underexposure. When the strobe has
recycled again, the ready light will again glow red indicating that the
strobe is fully powered and ready to re. If the strobe ready light does
not glow red, the batteries may be expended.
Your camera’s ready light “lightning bolt” in the camera viewnder may
blink while the DS51 is recycling and then glow solid when the DS51
is fully charged. Nikon DSLRs and older Canon DSLR models such as
the 20D and Rebel XT will always display a solid glow “lightning bolt”
regardless of the strobe cycle.
Ready Light with Remote Optical Slave Converter #4403
When using the DS51 strobe with the optional Optical Slave
Converter, the strobe is not electronically connected to the camera.
Therefore, the ready light in the viewnder of the camera indicates
when the on-camera ash has recycled. Examine both the camera
and strobe ready lights to make sure both ashes have fully recycled
before taking the next picture.
The Converter can be triggered off a camera ash or another strobe.
For more information about the Remote Optical Slave Converter
#4403, go to ikelite.com.

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Mode Switch
The DS51 Strobe mode switch has eight different positions: OFF, TTL/
auto exposure setting, and six manual exposure settings.
(Fig.1) (Fig.2)
(Fig.3) (Fig.4)
OFF position
(Fig.1) Shows the mode switch in the OFF position. The white
indicator on the knob aligns with OFF. Always turn the strobe to OFF
before connecting or disconnecting a sync cord or opening the battery
compartment.

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TTL/Auto Exposure Position
(Fig.2) Shows the mode switch in the TTL (Thru-the-Lens) / auto
exposure position. From the OFF position, rotate the switch clockwise
to access the TTL/auto exposure setting; the white indicator on the
knob aligns with TTL. When taking pictures with the mode switch in
this position, the camera automatically signals the strobe to turn off
when the exposure is correct.
•When the DS51 is connected directly to the camera, the camera
must feature compatible TTL/auto exposure to utilize this mode.
Manual Exposure Position
(Fig. 3) shows the mode switch in the manual exposure mode with the
DS51 Strobe turned to the F (full power) position. Rotate the mode
switch clockwise to access the different power settings. Each power
setting clockwise from F reduces the light output of the DS51 Strobe
in one-half f-stop increments. When shooting in the manual mode,
it is suggested that you start the strobe at full power and adjust the
camera’s aperture based on the strobe-to-subject distance.
If the subject in the photo is underexposed (dark) you must move
closer to the subject. If the subject is overexposed (light), then you
can rotate the mode switch clockwise to reduce the light output of the
strobe until the desired exposure is obtained. The DS51 provides ve
reductions in power in one-half f-stop increments from the full power
setting. (Fig.4) for example, shows the mode switch set to -1 and 1/2
f-stops.
Do not use manual strobe settings with a camera that emits “pre-
ash.” Leave the DS51 in the TTL position and adjust exposure
using your camera settings or housing conversion circuitry (if
applicable).

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Strobe Diffuser
Using the Diffuser
The white diffuser can be secured to the front of the DS51 strobe
when softer lighting or a coverage angle of up to 80° is desired. The
diffuser reduces the DS51 light intensity by one full f-stop.
Diffuser Installation and Removal
Tab
Push and Lift
to Remove
Tab
Holes for the
Lanyard
1. The white diffuser features two protruding tabs for use in installation
and removal. The tabs on the diffuser should be positioned away
from the strobe.
2. Place the diffuser over the front of the strobe. Spread the two tabs
apart, insert the diffuser into the recessed front, and then rotate the
diffuser until it locks into position.

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3. To remove the diffuser, bend one tab out towards the edge while
lifting simultaneously.
A lanyard or string can be attached to the diffuser by threading it
through the two circular openings near its edge. Attach the other
end to the strobe arm to prevent accidental loss.
Maintenance
Post-Dive
1. Always re-check o-ring seal after removing the battery door from the
strobe. Most importantly, make sure the o-ring is in place prior to
re-attaching the battery door.
2. Make sure the battery door is on and tightened down. Rinse your
strobe in fresh water. Do not remove the sync cord prior to rinsing.
Dry thoroughly.
3. NEVER leave your system in a fresh water rinse tank. Collisions
with other peoples’ gear can cause scratches or damage to your
equipment.
4. Stow your system in a shaded place where it is protected from
impact or overheating. If no shade is available, we recommend
covering the system with a towel or cloth.

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Cleaning, Travel and Storage
1. Always rinse the exterior of the DS51 with fresh water after use,
especially after exposure to salt water. While rinsing, turn the mode
switch to free salt or debris that might have accumulated in the
DS51 recesses during the dive.
2. Dry the DS51 thoroughly with a clean, lint-free cloth.
3. Check the battery door o-ring and sealing surfaces for any debris
and gently wipe it away with a soft, lint free cloth. Lightly lubricate
the exposed part of the door’s o-ring. Lubricant will help preserve
the o-ring, but does not assist the o-ring seal.
4. Check the DS51 bulkhead connector threads for debris. Gently
wipe away with a soft, lint free cloth or a cotton swab to clean the
threads. Afterwards, lightly lubricate them.
5. Remove the batteries and store the DS51 with the battery door
lightly screwed on (this will allow any hydrogen/air mixture to
escape the battery compartment and avoid placing unnecessary
pressure on the o-ring that could cause it to atten).
6. Store in a cool, dry place.
In addition to these procedures, it is strongly recommended that this
strobe be returned to Ikelite periodically for inspection and water
pressure testing. Ideally your DS51 should undergo this process
every two years or 100 dives, whichever comes rst.
Troubleshooting
Photos are over-exposed (too light)
• Adjust strobe exposure setting.

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• Adjust camera aperture (smaller), shutter speed (faster), or ISO
(higher).
• Move strobe(s) further away from your subject.
• Adjust exposure compensation in the camera.
Photos are under-exposed (too dark)
• Adjust strobe exposure setting.
• Adjust camera aperture (larger), shutter speed (slower), or ISO
(lower).
• Move strobe(s) closer to your subject and check aiming.
Strobe will not re
1. Turn on strobe.
2. Check the DS51 ready light. Turn the strobe’s mode switch to
OFF and then back to TTL. Make sure that the switch has actually
clicked into position.
3. Check that the batteries are inserted according to the “+” and “-”
markings. It is possible to buy bad “new” batteries, so check the
voltage output with a meter if possible. If using NiCad or NiMH
batteries, make sure the charger is operating properly and that the
batteries are fully charged.
4. Check the mode switches and cord connections on the camera
and strobe. Check that the ber optic cord or sync cord properly is
attached.

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5. When using a sync cord between the camera and strobe,
disconnect the cord from the camera but leave the cord connected
to the strobe. Then use the two ends of a bent paper clip to connect
different receptacles on the ash cord contacts, as detailed in the
diagram below. This process, known also as “shorting,” creates a
temporary circuit that can test-re the strobe.
Caution: When creating a circuit via paper clip, or “shorting,” pay
close attention to which two receptacles you connect. If you short
across the wrong receptacles on a TTL sync cord, you may damage
the DS51 electronics. The specic receptacles to connect with the
paper clip vary based on the type of cord you own. Please refer to
the diagram below.
Nikonos Sync Cord
Paper
Clip
Ikelite Sync Cord
Ikelite TTL Cord: Point the raised half-circle at the end of the cord
encompassing the receptacles towards you, per the above diagram.
Place one end of the paperclip on the center receptacle and one
end on the lower right-hand receptacle. The DS51 should ash.
Nikonos TTL Cord: Point the indexing groove at the end of the
cord towards you, per the above diagram. Place one end of the
paper clip on the top-most, center receptacle and one end on the
lower, right-hand receptacle. The DS51 should ash.
If the DS51 ashes, the source of the problem lies somewhere in the
camera. If the DS51 does not ash, please send both the strobe and
cord to Ikelite Service for evaluation.