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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,

 

https://www.instruct...D-E-M1-Mark-II/

 

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.

 

 

IMG_2318.jpg


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


#2 Yako

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Posted 23 May 2017 - 06:55 AM

great!


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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...

 

P7042148.jpg

 

P7042149.jpg

 

P7042145.jpg


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.


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#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.

 

Thanks!

Joss



#7 vsc

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Posted 29 August 2017 - 04:42 AM

The forum was (is?) not sending me updates on this thread. Perhaps my changes to the settings fixed that, but I'm not confident that what I changed will resolve the problem. And it isn't a spam email filter issue either.

 

With the camera cited in my original posting, with the Olympus housing, I found that the body can be rotated in the housing sufficient to upset the LED / fiber alignment such that the light emitted from the a fiber is insufficient to trigger the strobe. One of the two strobes in use was out of commission for the dive. This only occurred once where I found out in the process of shooting pictures of a pair of frog fish. Switching to an overhead strobe position with the remaining functional strobe yielded good shots... Actually very good shots to the point that I need to use that strobe position more often.

 

Normally I test the rig, shooting a frame or two, but I got lazy that day. It appears I also got hurried installing the camera into the housing. As such as part of setting up the rig look into the fiber mounting holes to ensure you can see the LED's in the center of the holes and/or shoot a frame or two ensuring your strobes fire. A standard strobe with its diffuser and much higher light output would never have this issue.



#8 vsc

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Posted 29 August 2017 - 04:44 AM

It is hard to say given these pictures given enough of the circuit card is obscured by the black tape. That said I strongly believe something similar could be done given most strobes use more or less similar implementations (e.g. IGBT, etc).

 

 

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 vsc, 29 August 2017 - 04:44 AM.


#9 vsc

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Posted 31 August 2017 - 03:45 AM

I just got back from two weeks of diving where the E-M1 mk II rig was in the water for dives averaging 90-120 min of bottom time. With the standard Olympus strobe mounted to the camera, I found that I still had 55-60% of the camera's battery life remaining after two such dives. Thus from a battery savings perspective the LED modification most likely doesn't make sense. Point in fact with the mk II, once it was sealed for the day I kept going and left well enough alone.

 
The YS-D2 strobes recycle time specified by the manufacture as 1.5 seconds maximum with Enloop batteries. While it is easy to show much quicker recycle times above water, thus permitting a rate of multiple frames per second, underwater at nominal subject ranges the loss through water is sufficiently great that I found it difficult to get the YS-D2 recycle time to under a second. On the other hand the Olympus strobe takes three seconds to recycle, which seems like eternity at times. The from this aspect the benefit is an overall recycle time of ~1 second. Clearly sometime this makes the shot. Note that the YS-D2 recycle times would be shorter in macro photography but there are few instances where this makes a difference and in those cases I normally use a different method to get the subject into view.