Jump to content


Photo
- - - - -

Olympus PEN & OMD Flash mod to reduce recycling time & battery

Olympus PEN OMD FLASH Mod

  • Please log in to reply
36 replies to this topic

#21 Glasseye Snapper

Glasseye Snapper

    Tiger Shark

  • Member
  • PipPipPipPip
  • 574 posts
  • Gender:Male
  • Location:Edmonton, Canada
  • Interests:Fish ID & behaviour and photos thereof

Posted 08 January 2014 - 08:09 PM

I just discovered this thread and it is a nice brain-teaser forcing you to think about how flashes and TTL operate. It reminded me of the flash trigger recently released by Nauticam but that one does not support TTL. However, after some thought I either don't understand how flashes work or there is a problem with this approach.

 

On my EM-5/Nauticam housing 100% of the strobe light comes from the external strobe as the camera strobe is blocked by the housing. My understanding is that flash light output under TTL is determined by controlling flash pulse duration. So if we need a given amount of light for our scene then we need a certain pulse duration. In turn that means that the pop-up flash on the camera needs to fire for that same duration. The way I see it, the only manner to reduce the energy consumed by the camera flash is to reduce its light intensity. I don't think using a smaller capacitor does that very effectively beyond perhaps lowering the average voltage over the pulse duration.

 

The oscilloscope images shown above seem to work but are misleading because they are "full flashes" that dump all the energy in the capacitor. This is not a fair comparison because the larger capacitors actually produce a proportionally stronger flash. In a real shooting situation where you need a fixed, non-maximal, flash output all capacitors are drained by the same absolute amount but different relative amounts. In other words if the shot requires a "25uF drain", the 100uF capacitor will have 75% of its juice left, while the 33uF capacitor is almost empty and the 10uF capacitor ran out of steam prematurely giving an underexposed image. This can explain the report where the smaller capacitor gave reasonable exposure in some situations but not others if  shooting conditions affect the required strobe output (ISO, aperture, subject distance/color, ambient light, etc). Reality may be a bit more complicated because the smaller capacitor will lose voltage faster as it drains but if I am correct then I don't think this approach will work satisfactorily. What is needed is a different light source that can handle the voltage coming off the capacitor but has a light output just enough to trigger the external flash. I read on wikipedia that "photoflash capacitor is an electrolytic capacitor used in flash cameras, professional flashes, and also in solid-statelaser power supplies." A tiny laser that directs its light right into the fiber optics would need a tiny amount of energy but I have no clue if cost, size or other limitations prevent that from working.

 

Bart

 

PS: looking at the Nauticam flash trigger it seem they use either a laser or more likely a LED, which is somewhat related to a laser.


Edited by Glasseye Snapper, 08 January 2014 - 08:14 PM.

Olympus OM-D EM5/Nauticam, 12-50mm & 60mm macro
Sea&Sea 110a, iTorch, GoPro3 BE

#22 AYahoo

AYahoo

    Clownfish

  • Member
  • Pip
  • 25 posts

Posted 08 January 2014 - 11:16 PM

Hi Guys, I was a little bit busy lately, but I'll try to answer some of the questions...

 

I am not sure if I understand the graph, but I assume the y-axis is capacity and the x-axis is time (it would help to have a scale :-)

 

My bad, the Y is V (each div is 50v) and the X is time (ms).

 

Thanks for the test and info, I saw your thread only now but it is very interesting.

...2 if you limit the energy of a flash by the capacitor, you will loose out one the maximum possible duration (power)

 

I'm interested to know how the electronics of the flash looks like and what pins they are using if you have any pictures?

 

...However your TTL experiment is interesting, As well a quenching the flash tube, the camera can quenche a LED or laser.

 

Cheers

/O

 

I think you are semi right about the "loose out one the maximum possible duration" assumption, since the camera doesn't know the size of the flash installed, and the size of the strobe setup (can be 10 external strobes working together) this is the key feature that you are missing, I can install a very big flash on my hotshoe and still get a correct exposure of the image. so I think the Olympus Eng. deiced to use the size of the capacitor that will get a good coverage of daily use, since we are not using the same setup as they predicted (external strobes), we don't need that big of a capacitor, I did many tests will all kind of capacitors, I think that the magic number is around 30-50uf, I've used the 30uf and during the test only one extreme situation was under exposed compared with the original (f22 1/160) with big distance to the object, so I've ordered the same brand and same specs as the original capacitor but 50uf to test and check (I will update when I will get it).

 

Regarding the pins, I was also interested, but I didn't get there, I still have it disassembled and I might have time in the next few days to check it.

 

Other than that, I will try to update soon, but I took my friends RX100 MK2 and disassembled it completely, it had two capacitors 1x48uf and another 33uf connected in series, so 81uf total, again tried many settings ended up with 1uf capacitor to only trigger the external strobes, NO TTL! but we managed to take 2-3 photos per sec compared with 1 photo every 4 sec with the original, so about x10 faster. (didn't check battery consumption but I'm sure it will be much better).

 

Last but not least, I've tried to trigger a led, to check if I can get better results, but I had some success but not enough time to investigate it properly.


Edited by AYahoo, 08 January 2014 - 11:18 PM.


#23 simonknee

simonknee

    Triggerfish

  • Member
  • Pip
  • 36 posts
  • Gender:Male

Posted 10 January 2014 - 06:40 AM

Hi,

 

Just picked up on this and it is a very interesting idea.

 

I have a hunch that when you use a flash-specific capacitor you may no longer get the results we desire.

I think that the reason this is working is that the standard-grade capacitors you are using have a slower maximum discharge speed due to higher internal resistance.

This is causing reduced flash intensity and so allowing the same duration of flash for less power as the standard size capacitor.

With a proper high-speed flash capacitor you will not be able to achieve this any more.

 

Lets see if your next test bears this out or not.

 

My concern is that if this is the case and you need to use standard-grade capacitors to achieve this effect then you run the risk of overheating the capacitors as they are really designed for use in power supply smoothing applications not high-speed discharge.

However this makes me wonder if there is an alternative mod we could do using the standard capacitor but increasing the series resistance slightly. Have you tried this on your test bed? EDIT - though this would limit the charging speed too so not a great idea

 

Simon


Edited by simonknee, 10 January 2014 - 06:44 AM.


#24 Glasseye Snapper

Glasseye Snapper

    Tiger Shark

  • Member
  • PipPipPipPip
  • 574 posts
  • Gender:Male
  • Location:Edmonton, Canada
  • Interests:Fish ID & behaviour and photos thereof

Posted 10 January 2014 - 10:47 PM

My electronics knowledge is very dusty but aren't they two separate circuits. You can charge the capacitor without it being "connected" to the flash light, so if you put the resistor after the transistor, or whatever controls the connection between the capacitor and light, then it will only affect the discharge.

 

Still the ideal situation is to use a light with higher resistance/lower wattage and that focuses its lumens into the fiber optic rather than spreading it out over a broad area. So I am very curious about the test with triggering a LED.

 

Bart


Olympus OM-D EM5/Nauticam, 12-50mm & 60mm macro
Sea&Sea 110a, iTorch, GoPro3 BE

#25 simonknee

simonknee

    Triggerfish

  • Member
  • Pip
  • 36 posts
  • Gender:Male

Posted 11 January 2014 - 02:39 AM

Possibly Bart, though I am aware that adding resistance to any part of a working circuit without a proper understanding of what the designers intended might just render it useless.

I too wonder about led, from a quick Google hunt it seems that there is success as a trigger but not as a ttl.

Retro fitting a lower output xenon is another option. Not sure how to source such a thing mind. Most suppliers of xenon tubes want to advertise how bright theirs are!

Sent from my Nexus 4 using Tapatalk
 


Edited by simonknee, 11 January 2014 - 03:22 AM.


#26 AYahoo

AYahoo

    Clownfish

  • Member
  • Pip
  • 25 posts

Posted 13 January 2014 - 12:14 AM

I Haven't received the capacitor yet, but I'm thinking about implementing a cell phone led flash... this will be the easiest (I think :)).



#27 simonknee

simonknee

    Triggerfish

  • Member
  • Pip
  • 36 posts
  • Gender:Male

Posted 14 January 2014 - 02:54 AM

What are your thoughts on how to implement LED trigger/quench since the voltages floating around are not exactly suitable to say the least!

 

Simon



#28 oskar

oskar

    Eagle Ray

  • Member
  • PipPipPip
  • 343 posts
  • Gender:Male
  • Location:Stockholm

Posted 14 January 2014 - 04:34 AM

It would be great If you could reverse engineer the pin layout and protocoll for controlling the flash!
 
 
This would open up some options for sure.   My thinking is that it would be possible to do a simple 
LED TTL strobe as it seems to me that all logics are in the camera, so that the camera control the strobe
with a trigg and quench signal.    (I'm guessing based on images earlier in the thread.)
 
It would be good if you got the oportunity to take some more pics on the hotshoe connections and the circuits
top and bottom.
 
For making a LED strobe, i would choose to use a separate lithium battery, but I suppose it should be possible 
to use the camera battery to, as there must be a pin with the 4.2 V from the camera battery for charging the 
the standard flash.
 
 
 
 
However, I have made good with non-TTL for now, so maybe I should try to se if I like it before building something elaborate 
:-)
 
 
BTW, interesting mod on the RX100mk2,  As it does have a hotshoe it seems better to use a microstrobe rather than to cripple 
it. However, it's an excelent mof for the mk1 without hotshoe!  


#29 simonknee

simonknee

    Triggerfish

  • Member
  • Pip
  • 36 posts
  • Gender:Male

Posted 14 January 2014 - 10:02 AM

I opened up the rest of the flash at the weekend and I suspect that the complex little circuit precludes reverse engineering. It is a double sided pcb with a bunch of surface mount stuff. I could not find one of the two 10-pin SMD packages when I searched online. Personally I think modding a circuit that already does the job as Olympus intended is the best route.

 

I am going down the other track and have ordered a spare xenon for a mobile phone camera (Nokia 6022) to see if it is lower power.

 

Simon



#30 AYahoo

AYahoo

    Clownfish

  • Member
  • Pip
  • 25 posts

Posted 15 January 2014 - 11:02 AM

I've opened it up also... I'm trying to see the writing on the chip with no success...  Clownfish do you a pic of the circuit? I'm attaching mine... but I can't seem to see what is written on the main chip (looks like a small microcontroller).

 

P1015549.jpg

P1015557.jpg

If we look at the connector from left to right top row first then.

 

1 - NC (Not Connected)

2 - NC

3 - GROUND

4 - NC

5 - NC

6 - NC

7 - NC

8 - NC

9 - NC

10 - NC

11 - NC

12 - NC

13 - NC

14 - ??

15 - ??

16 - GROUND 

17 - ?? (Connected also to 30)

 

 

 

18 - GROUND

19 - NC

20 - NC

21 - GROUND

22 - NC

23 - NC

24 - GROUND

25 - NC

26 - NC

27 - GROUND

28 - NC

29 - NC

30 - ??

31 - NC

32 - ??

33 - ??

 

So there are 5 pins working... 14,15,17 (30), 32, 33 So who will lift the glove to do the reverse eng...


Edited by AYahoo, 15 January 2014 - 11:50 AM.


#31 simonknee

simonknee

    Triggerfish

  • Member
  • Pip
  • 36 posts
  • Gender:Male

Posted 17 January 2014 - 08:07 AM

So a smaller tube arrived and I put it in. I think it was faster. However testing of recharge time was curtailed by a bigger issue. With my 50mmf2 attached as soon as I go smaller than F16 on my EM-1 the FL-LM2 gets unreliable and more often than not completely over exposes. Perhaps I have damaged my FL-LM2 so I need to buy another before I can reach any conclusions... 

 

EDIT: I put the original tube back in and the problem is without any UW strobe or housing. Plus I did a full reset in case I had mucked up a setting. The flash/camera might have had this problem from day one so glad I've been fiddling and spotted this since it would have made shooting underwater very haphazard.


Edited by simonknee, 17 January 2014 - 08:16 AM.


#32 simonknee

simonknee

    Triggerfish

  • Member
  • Pip
  • 36 posts
  • Gender:Male

Posted 17 January 2014 - 08:59 AM

OK I was able to do some testing even with the >F16 fault.

 

These are the original tube (large) and a tube from a Nokia phone.

 

IMG_20140117_134641.jpg

 

EM-1 in Nauticam NA-EM1 housing optically firing a Sea&Sea YS-01

Setting the camera to F14 and shooting the same test scene

YS-01 lights green to show TTL.

Pictures expose the same with either bulb.

 

But the nokia tube is draining the battery MORE!

It takes three blinks of the flash icon on the LCD for the original tube.

Yet four blinks for the smaller Nokia.

In both cases the YS-01 recharges in under a second but it is taking 3-4 seconds for the FL-LM2.

 

Ho hum - to be fair I have no specs on the nokia tube other than it's size.

Worth a punt mind.

 

Simon



#33 oskar

oskar

    Eagle Ray

  • Member
  • PipPipPip
  • 343 posts
  • Gender:Male
  • Location:Stockholm

Posted 22 January 2014 - 04:06 AM

Good to se your experimenting on!
 
Just very quick comment:
 
A flash tube does not work like a light bulb with different power ouputs.
 
The flash tube is a gap when not ignited, once the tube ignites and the plasma is created, it acts basically like a short circuit.
 
If you get a smaller tube, it has different characteristics, like what voltage you need to ignite it, and what power it can handle without beeing damaged.
 
But once you ignite it it is basically a short circuit just like the bigger tube, but probably slighly lower resitance still. It will empty you capacitor completely if not quenched by a cicuit.
 
Cheers
/O


#34 Yako

Yako

    Clownfish

  • Member
  • Pip
  • 28 posts
  • Gender:Male
  • Location:El Sauzal - Canary Islands - Spain

Posted 22 January 2014 - 09:36 AM

Hi,

 

Anyone could tell me how to open FLM-2 flash (the new one that comes with the OMD EM5 or EM1)?  

 

For FLM-1 it's easy because you see two screws, but for the FLM-2 I don't see it...

 

I have changed the original capacitor of the FLM1 unit with 1uF capacitor and it works well in manual mode using OMD EM5 and S&SD1.

 

 

The problem is that this unit is higher than FLM2 (several mm) and when I put the camera+FLM1 inside the Nauticam Housing, the head of the flash is not pointing directly to the FO holes...

 

Now I have a second hand FLM2 and I would like the same capacitor change....


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

 

My Flickr Gallery


#35 simonknee

simonknee

    Triggerfish

  • Member
  • Pip
  • 36 posts
  • Gender:Male

Posted 23 January 2014 - 10:42 AM

Screws are all underneath sticky tape. Flip the flash up and remove the bit of tape. You will find the ones you need to take the top cover off.

Sent from my Nexus 4 using Tapatalk

#36 Yako

Yako

    Clownfish

  • Member
  • Pip
  • 28 posts
  • Gender:Male
  • Location:El Sauzal - Canary Islands - Spain

Posted 24 January 2014 - 01:46 AM

Ok, Great!!



Thanks a lot, simonknee!!


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

 

My Flickr Gallery


#37 simonknee

simonknee

    Triggerfish

  • Member
  • Pip
  • 36 posts
  • Gender:Male

Posted 27 January 2014 - 04:43 AM

Testing of resistance mod:

 

(my erratic exposure above F16 was down to the erratic closing of the aperture blades on my 50f2, I am now testing with my 11-22 @22mm as it is a happy snapper at all apertures)

 

So in an effort to increase the resistance of the tube (and use less power) I added some resistance.

 

I soldered in a 1ohm 5watt wirewound directly to the anode of the tube (pic later).

The flash still worked but this made little difference to recharge times.

There is plenty of power going through here which soon destroyed a 10ohm 1W carbon resistor (nice internal explosions).

So digging about in the component drawers I settled on a 6R8 (that's 6.8ohms) 22W wire wound resistor.

I will try and do the maths on what is a suitable wattage later - suffice to say please be careful if you try this, no fires please. 

 

When testing in the housing with a pair of Sea&Sea this shaved 1/3 off the recharge time compared to an original FL-LM2.

However reviewing the images from my resistive flash showed that as the aperture got smaller the exposure got brighter (tried another lens to confirm)

AT F10 exposure was the matched, at F22 it was approximately 1 stop brighter using the resistive flash.

I guess the mod upsets the pre-flash a bit and causes the EM-1 to think it needs more light.

So I stopped down the flash (on the EM-1) to match exposure and of course recharge time was even quicker.

The camera was able to keep up with the recharge of the S&S (YS110a & DS-01) on a dining room table test at least.

 

This is a double-edged sword for me since though it appears predictable it means there is more to remember to adjust which isn't really the ethos of TTL. Though adjusting flash exposure at the camera is much easier than in manual on each of the strobes.

 

Onwards and sideways

 

Simon

 

EDIT: As to this mod upsetting the pre-flash I did notice that the light produced by the flash dropped away more dramatically than the original as you moved down the full, 1/2, 1/4, 1/8 ... flash settings (tested on it's own out of housing). The resistor mod does appear to adversely affect shorter flash times (perhaps it causes a tiny start delay?). This does mean that there may be issues with short flash durations even in the housing - only UW testing will tell if these shorter durations are even needed.


Edited by simonknee, 27 January 2014 - 05:10 AM.