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EFCS & Flash in LV Circuit
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mawyatt



Joined: 22 Aug 2013
Posts: 1595
Location: Clearwater

PostPosted: Fri Jan 19, 2018 8:44 am    Post subject: EFCS & Flash in LV Circuit Reply with quote

I'm in the process of designing and building a Delay Circuit Module to enable EFCS with external Flash while operating the Nikon D850 & D500 in Live View while doing extended stacks.

The general idea is to trigger the camera and Delay Circuit Module from the stacking controller (Stackshot or WeMacro), the delay circuit will match the camera to shutter delay and thus allow the flash/strobe to fire while the camera electronic shutter is effectively "open", thus exposing the sensor. I've already done this with a wired trigger "splitter" and using the delay feature in the XPLOR 600 strobe, and using the optical flash from the XPLOR to trigger the other strobes (as a Master) using the "S1" optical trigger mode. Details are here.

https://www.photomacrography.net/forum/viewtopic.php?t=36194

I want to be able to do this procedure with any of my strobes and speedlights without using the XPLOR 600 as the Master, thus a generic solution for all strobes/speedlights and hopefully cameras with EFCS capability.

So to start this design effort I needed to know what the trigger outputs "look" like electrically from my Stackshot and WeMacro controllers. The Stackshot controller provides a built-in open circuit voltage of 3.5 volts and a short circuit current of 3.2ma, this implies a "pull up" resistance of 1.09K ohms. The WeMacro is just an open contact of a relay with no voltage nor pull up. So these two controllers have totally different output trigger circuits.

Now the Nikon D850 trigger input has an open circuit voltage (OCV) of 3 volts and short circuit current (SCC) of 1ma, so a pull up of 3K ohms, I suspect the D500 is similar although I haven't tested it just yet.

Here's what I found on the Adorama R2 RF Trigger, OCV of 3.14V and SCC of 133ua or 24K ohm pull up.

And of my strobes (haven't measured all of my strobes or speedlights but expect them to be similar).

Adorama Studio 300 AC, OCV of 4.79V and SCC of 440ua for pull up of 10.9K
Adorama DG-600, OCV of 4.63V, SCC of 134ua for pull up of 35K
Adorama 320M, OCV of 6.03V, SCC of 178ua for pull up of 34K
Adorama Speedlight Zoom Li-On of OCV 3.06V and SCC of 215ua for 14K

So this gives a good idea of what the inputs and outputs of the delay timer must be compatible with.

Because the WeMacro is an open circuit contact relay (NO), then some means of detecting the falling edge of the relay contact is required if the delay circuit is to be triggered. Normally this is provided by the camera trigger input which is shown to have 3V with a 3K pull up.

I've designed two separate inputs for the Delay Circuit Module, one is direct where the trigger circuits provides it's own voltage and pull up but resistively isolated, the other is a self powered optically isolated input that derives it's trigger pulse power from the input source. Between these two inputs should cover just about any input trigger source I can think of at the moment.

With all the possible output combinations I've decided to use 2 independent optical coupled outputs with open circuit NPN transistor collectors, so they are polarity sensitive.

The delay timer circuit module is to be powered from the 12V power for the Stackshot or WeMacro controller using a cable "Y" adapter, or directly from another source. Also have the ability to use a module voltage regulator to allow operation over a wide range (~7 to ~20 volts), but don't think I'm going to include this as the 12V power is pretty stable from what I've seen. BTW the circuit operation is somewhat independent of the supply voltage.

The core delay circuit is based upon the well known 555 timer configured as a pair monostable "One Shot" multivibrators. The first One Shot is triggered from the external trigger source and has a variable delay of ~4ms to ~409ms, set by a precision multi-turn potentiometer. This delay is normally set to the camera trigger to shutter delay (D850 52/145ms manual and LV, D500 49/103ms).

The output of the first One Shot triggers the second One Shot which has a fixed ~100ms pulse width to enable the optical coupled outputs. A couple LEDs show the trigger delay and output pulse.

This is the design I've conjured up while taking my afternoon walks. Yes, I do these in my head while walking, then jot them down later.

So why all the details?? Well, I'm ordering the parts for the Delay Circuit Module (DCM) and decided to offer the design and components for those that would like to use it with their EFCS cameras in LV.

I believe that the DCM should work with any camera with EFCS (Canon, Sony, Olympus) in Live View but I'm only testing it on the Nikon D500 and D850 I have. The D810 should work as well.

Please indicate if you are interested in the DCM I'll try and order enough parts to supply them.

Please DON'T indicate YES if:

A) You don't have a EFCS camera
B) You aren't familiar with building electronic circuits from scratch
C) You don't know how to read a hand draw schematic
D) You don't know how to use a VOM and know how they work
E) You don't know resistor color code & capacitor numerical codes
F) You don't know about IC pinouts
G) You don't know about diode, transistor & capacitor polarity

I really don't want to end up having to teach electronics, this isn't the right venue for such!!

Anyway, my plan would be to offer the main electronic components (sans case and cables) to those folks interested, especially those that have provided such great help and guidance here, if they would send a self addressed prepaid cushioned envelope.

For now just indicate your interest. I don't plan to charge for the basic components, but if it gets too expensive then this may change Rolling Eyes

Once I get the DCM built and tested I'll provide and detailed schematic with component values indicated, and pictures on the built hand wired circuit.

If someone decides they want to create a Printed Circuit Board for a more "Professional" looking result, that would be great Laughing

BTW please let me know ASAP, as I need to get the parts ordered!!

Best,

Mike
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ChrisR
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Joined: 14 Mar 2009
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PostPosted: Fri Jan 19, 2018 10:24 am    Post subject: Reply with quote

I'd like to to put your circuit together - I'm sure I can source the components in the UK.
I designed my own - but that's as far as it got. Embarassed
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mawyatt



Joined: 22 Aug 2013
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PostPosted: Fri Jan 19, 2018 11:34 am    Post subject: Reply with quote

Chris,

Here's the preliminary schematic from my notebook, haven't built nor tested anything yet.




Just noticed that the 100 ohm resistor left wire should extend to the center contact of the circular symbol for the Optional Optically Isolated Input connection/connector.

Best,

Mike
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Steve S



Joined: 10 May 2013
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PostPosted: Fri Jan 19, 2018 1:37 pm    Post subject: Reply with quote

Count me in. This is most thoughtful of you and goes a a fair ways towards restoring my bruised and battered faith in human nature -- but then I'll surf over and read about the budget continuing resolution "negotiations" and that will be the end of that. Now if I can just remember which end of the soldering pencil is the hot one . . . it's been a while.
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ChrisR
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PostPosted: Fri Jan 19, 2018 1:50 pm    Post subject: Reply with quote

Steve it's the one which goes smelly when you touch it.
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mjkzz



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PostPosted: Sun Jan 21, 2018 7:26 pm    Post subject: Reply with quote

if you are in a hurry, you can use that water drop kit, the top input can be connected to hotshoe, dial in the delay in ms, and connect your flash to the flash port on the controller.
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mawyatt



Joined: 22 Aug 2013
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Location: Clearwater

PostPosted: Sun Jan 21, 2018 8:19 pm    Post subject: Reply with quote

mjkzz wrote:
if you are in a hurry, you can use that water drop kit, the top input can be connected to hotshoe, dial in the delay in ms, and connect your flash to the flash port on the controller.


Peter,

See link above, I mentioned your water drop controller.

https://www.photomacrography.net/forum/viewtopic.php?t=36194


"While watching the Rose Bowl Parade I realized that the same technique for capturing a water drop image can be used to enable flash with the EFCS in Live View by delaying the flash command after the exposure has started.

Peter at MJKZZ has a water drop controller that should work by delaying the flash until after the EFCS has opened.

http://www.mjkzz.com/product-page/six-valve-controller

Another delay solution if you don't have speedlights/strobes with a built in delay function is as shown. This should cost less than $3 from eBay.

Best & Happy New Year,

Mike"
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billjanes1



Joined: 30 Dec 2016
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Location: Lake Forest, IL, USA

PostPosted: Mon Jan 22, 2018 5:31 am    Post subject: Reply with quote

mawyatt wrote:
Chris,

Here's the preliminary schematic from my notebook, haven't built nor tested anything yet.

Just noticed that the 100 ohm resistor left wire should extend to the center contact of the circular symbol for the Optional Optically Isolated Input connection/connector.
Mike


Mike, Count me in too. I have ordered parts for the timer circuit that you posted previously, but all of them have not come in. How does your newer scheme differ?

Regards,

Bill
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mawyatt



Joined: 22 Aug 2013
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PostPosted: Mon Jan 22, 2018 6:29 am    Post subject: Reply with quote

billjanes1 wrote:
mawyatt wrote:
Chris,

Here's the preliminary schematic from my notebook, haven't built nor tested anything yet.

Just noticed that the 100 ohm resistor left wire should extend to the center contact of the circular symbol for the Optional Optically Isolated Input connection/connector.
Mike


Mike, Count me in too. I have ordered parts for the timer circuit that you posted previously, but all of them have not come in. How does your newer scheme differ?

Regards,

Bill


Bill,

The other design should work fine also, it's based on a ready made module with some modifications and added circuitry to support the desired function (negative going output trigger for flash). I ordered the module also, still haven't received it, but probably won't build the circuit because the other is more flexible.

The one shown here is not based on a ready made module. It has optical isolated outputs (actually two outputs), uses a second 555 monostable to create the output trigger pulse, optional regulators & trigger source powered optical isolated input.

So it's a more universal delay timer, should work with just about any trigger source, camera and strobe/speedlight.

Best,
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mawyatt



Joined: 22 Aug 2013
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PostPosted: Sat Feb 24, 2018 3:25 pm    Post subject: Reply with quote

Finally got back in town and had enough time to put this together on a plug in breadboard, parts came in too.

Good news is it works as expected, bad news is I won't be able to properly solder this on a board as a loss in the family will consume my time for next few weeks.

Here's the schematic, only significant change is the input is capacitive coupled rather than direct (was having some sensitivity issues with direct couple scheme). The tolerance on the components isn't critical as indicated.

I've tested this with a Nikon D850 and Adorama DG600 strobe & 300 Studio Strobe utilizing direct wired triggered, Adorama R2 RF remote triggered and an old Neewer RF (433MHz) RF trigger.

After initially setting the delay pot near the required resistance (~120K) for the delay for the D850 (145ms). The D850 was set to EFCS mode and triggered from a Stackshot controller in Live View, the shutter speed was initially set to 1 second. The delay was adjusted until the image was fully captured, then the shutter was reduced to 1/5 and the delay adjusted until the image was captured without any shadows, then 1/10 and 1/20 and repeated. I found the D850 will have some variation in it's delay response in Live View, especially if an external monitor is used. Since any delay variation in the camera will show up in the moment the image is captured, this could cause a shift between the effective shutter opening and the strobe firing, since these are no longer synched by the camera. This isn't a problem normally because the camera initiates the strobe trigger signal from the hot shoe, thus any delay variation in the camera from an external trigger doesn't effect the trigger of the hot shoe signal relative to the shutter, however we are going around this because Nikon doesn't allow the camera hot shoe trigger in EFCS. Because of this variation in delay I've used a shutter of 1/10 to allow for this in camera shutter delay variation. I might tighten this up later but at 1/10 I see no exposure from ambient light, so the image is being only exposed by the strobe, and I see no shadow effects from the shutter.

Under these conditions the delay trigger system works whether directly attached to the strobes, or by Neewer or Adorama RF triggers. No changes in the delay setting was required when switching between the direct and RF triggers.

Here's the schematic used, and the wired plug board.



Note, D1 are optional LEDs and Trigger Input is on schematic left and Delay Trigger Out is on right.

See the first post for details if you want to build this Delay Trigger Circuit. I'll reserve a few core parts for contributing members that are skilled in scratch electronics assembly & test. Please PM me and send a prepaid and pre-addressed self return cushioned envelope.

Think I know why Nikon doesn't allow flash while in EFCS mode in Live View, or at least a reason to be cautious when using such. Since EFCS has no conventional shutters, the possibility of intense short duration light (like from a strobe or speed-light), occurring after the shutter period causing an image problem is high. Without a mechanical shutter in Live View the sensor is optically exposed after the shutter period during readout, no mechanical shutter nor mirror to block the optical path. The optical light burst could contaminate the pixels before or during the readout phase and corrupt the final image after the shutter period. I've seen evidence of this with partially exposed subjects appearing in the image after the electronic shutter has "supposedly closed" but the optical flash duration extends beyond the specified shutter period outside the exposure period window. It looks like a dark band as expected except some of the subject is shown thru the dark horizontal bands, looking like a bleed-thru effect.

Best,
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rjlittlefield
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PostPosted: Sat Feb 24, 2018 5:10 pm    Post subject: Reply with quote

mawyatt wrote:
Think I know why Nikon doesn't allow flash while in EFCS mode in Live View, or at least a reason to be cautious when using such. Since EFCS has no conventional shutters...

I'm confused. My understanding is that EFCS = Electronic First Curtain Shutter, with the second curtain being mechanical as always. Does your D850 not end exposure with a mechanical shutter?

--Rik
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mawyatt



Joined: 22 Aug 2013
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PostPosted: Sat Feb 24, 2018 5:20 pm    Post subject: Reply with quote

rjlittlefield wrote:
mawyatt wrote:
Think I know why Nikon doesn't allow flash while in EFCS mode in Live View, or at least a reason to be cautious when using such. Since EFCS has no conventional shutters...

I'm confused. My understanding is that EFCS = Electronic First Curtain Shutter, with the second curtain being mechanical as always. Does your D850 not end exposure with a mechanical shutter?

--Rik


Rik,

I think that is how it works in Live View, but not absolutely sure. When using the View Finder I believe the mechanical rear curtain is used to terminate the exposure, but not in Live View....it's terminated electronically and thus possible to penetrate the electronic shutter while in read out phase.
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rjlittlefield
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PostPosted: Sat Feb 24, 2018 5:48 pm    Post subject: Reply with quote

When collecting images continuously in Live View or in video recording, for sure there is no mechanical shutter involved.

But I have read nothing that indicates a single ordinary exposure is ended by electronic shutter.

On the other hand, I cannot think how to explain your ghost images except by having an electronic shutter involved somehow. I wonder if they're actually running an electronic shutter with a mechanical shutter shortly behind it?

I'm curious about how your exposures behave on a human time scale. I'm used to Canon cameras with EFSC, where start of exposure is functionally silent (just the ever mysterious quiet zing), but end of exposure has the distinct click of mechanical shutter closing.

What does your Nikon sound like, at end of exposure?

--Rik
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mawyatt



Joined: 22 Aug 2013
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PostPosted: Sat Feb 24, 2018 6:08 pm    Post subject: Reply with quote

I can hear the shutter and mirror in other modes, but with EFCS in Live View it is totally quite, no sound that I can hear.

If this is true, then Nikon made the decision to not allow Hot Shoe Triggering when in EFCS and Live View, rather than risk a corrupted image. Considering the various usage forms, this probably was a good decision considering overall usage.

Maybe someone will hack the D850 code and override the Hot Shoe Trigger override Rolling Eyes

Don't know if the D810 works this way (don't have one) or the D500 (not in my setup now).
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mjkzz



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PostPosted: Sat Feb 24, 2018 6:57 pm    Post subject: Reply with quote

Mike, pardon my jumping in, I am totally impressed by your skills building this, to me, it looks like my college lab class 20 years back :-)

If you just want to have some delay, I think a microprocessor unit is much easier and cleaner to implement it. All you need is a 1 dollar MCU (could be less), a 2N3904, a resistor, maybe a POT to adjust delay.

I will write a blog about how to program an 8-pin AVR and use your use case as example. But an Arduino is needed to act as chip programmer. Then again, with an Arduino, you do not need to use an 8-Pin MCU any more. But just for the sake of "coolness", an 8-Pin solution is probably good idea., plus you can use the Arduino as programmer for other projects.
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