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LED Strobe Trigger For Olympus OM-D E-M1 Mark II

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#1 vsc


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Posted 22 May 2017 - 05:39 PM

An older thread discussed modification of an Olympus flash to reduce cycle time and battery consumption. While the results were mixed, I was motivated to create a functionally equivalent solution for the Olympus OM-D E-M1 Mark II without any limitations. Using an Olympus FL-LM3 flash I substituted LEDs in place of the Xeon tube, enabling triggering an external strobe (e.g. Sea&Sea YS-D2) preserving TTL functionality while reducing cycle time and battery consumption.


Micro 4/3's cameras use a serial protocol between the camera and flash which is closed to the public. Looking at the bit stream I quickly decided it was a waste of time to reverse engineer the protocol and turned to simply modifying the Xeon strobe subsystem of the flash. In short remove the Xeon tube, trigger transformer, disable the discharge path for the photoflash, substitute a small (e.g. 1 uF photoflash cap) for good measure and add a LED driver and LEDs. The FL-LM3 is a traditional modern strobe using a IGBT to not only drive Xeon tube, but also the trigger transformer. Stop the strobe as part of TTL metering, the IGBT device is driven into pinch off, thus quenching the Xeon tube, leaving whatever charge is left on in the capacitor. This enables the flash to emit pre-flashes, as well as the main flash.


By connecting the LED driver to the IGBT's gate, the LEDs emit exactly the same duration light pulses as would have been emitted by the Xeon tube preserving the pre-flashes, etc.


The following is a link to the instructions for this modification,




Also a link to a video showing an E-M1 Mark II in an Olympus housing with the modified flash, triggering a Sea&Sea YS-D1 running at frame rate limited by the communication rate between the body and FL-LM3. Note this is somewhat of a trick given if the YS-D2 recycle time increases the frame rate must drop, but there is no feedback to the body. Thus setting the body to run at a lower frame rate is the path forward.




Edited by vsc, 22 May 2017 - 05:44 PM.

#2 Yako



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Posted 23 May 2017 - 06:55 AM


Olympus OMD E-M1, Naticam housing, 2x S&S D1, Oly 60mm , 12-50mm & 12-40mm, Pana 8mm & 7-14mm


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#3 Draq


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Posted 23 May 2017 - 10:21 AM

Great idea,  If you or someone else were to make some of these and sell them, I would definitely be interested, in the absence of a commercial ttl trigger for Olympus.  For me DIY involving electronics and other small delicate things is likely to turn into BIY (break it yourself) so I don't do much of that. 

#4 ProfF



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Posted 04 July 2017 - 07:58 AM

Hi, cool idea!


I am wondering whether a similar mod can be done to the FL-LM2 (the smaller flash of Mark I OM-Ds). Anyone with electronic background can comment on whether this mod will work?


If it helps,  I disassembled my older LM2 and attached photographs. As far as I can tell, the xenon tube assembly is similar to that of the LM3. Any suggestions how to proceed will be appreciated...







Edited by ProfF, 04 July 2017 - 09:27 AM.

Olympus OM-D EM1, Nauticam NA-EM1, Olympus 9-18mm, 12-50mm, 60mm lenses, Panasonic 8mm, Sea & Sea YS-D1 x 2.

#5 Jock


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Posted 04 July 2017 - 12:42 PM

Ha! Yesterday I disassembled an old non-functional FL2 myself and wanted to post photos and the very same question as well. Funny. Hope someone can help.


Olympus OM-D EM5, Inon Z240 and Nikonos RS, Ikelite SS200

#6 Joss



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Posted 15 July 2017 - 03:03 AM

Hello, thanks for putting this together and sharing.

I'm definitely interested.

However, i don't have any electric / electronic skills and the best for me will be to get your bill of materials and instructions to a electronic repair shop.