Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

Started May 21, 2012 | Discussions
RussellInCincinnati Veteran Member • Posts: 3,201
it's not *necessary* to kill the flash's output, 1 of 2

Fabianbono: it's amazing how a brainstorm like this can provide these results.

Of course this is the Holy Grail of a free public forum. Every once in a while something of value gets created from the forums, that realistically would not have happened without them. Put another way, the main idea of a forum is not call each other idiots, etc.

Fabianbono: First...My C3 is my family camera, so it is used by ...iAuto mode (that I must set before turn it off!!) and ...some case, use the flash.

Well then it would make sense for you to leave the flash tube in your modified flash, and also to not disable the hinge switch. Hmm, even better, have the hinge switch work in parallel with the Yongnuo RF603 switch, so that either raising the flash or hitting the Yongnuo switch would turn everything on.

Fabianbono: Also sometimes I don't want to travel with a full bag of stuff, just the camera on his small bag hung from my shoulder.

You are starting to make me think that the way to do this is glue "velcro" on top of the flash, and the bottom of the RF603, with a tiny "plug" between the flash and the RF603 that can be disconnected also. This plug would be a little ribbon cable, there would be more than a couple of wires between the devices with my scheme.

A nice thing about my proposal is that the velcro would be strong enough to hold the 38 gram RF603 on it, because that's the only thing the velcro would be holding onto. In the case of the RF603 being a radio trigger with nothing further attached to it.

Fabianbono: Then, I need to have available the original flash too, just in case I use the C3 as Point and Shot.

Am forcing myself to keep in mind, that there is no law against owning 2 little Sony flash units. One modified, one standard. Remembering that for anyone with a serious interest in proper viewfinder behavior and radio flash, "wasting" 40 dollars on a Sony flash to be turned into a radio trigger (with the addition of a $17 dollar part plus a few resistors, transistor etc) is not a terrible expense at all.

Fabianbono: And last, also I like to use the C3 mounted on a bracket, with the Yongnuo 560II flash at side, just connected by PC cable, without using Wireless triggers.

You don't have the wireless trigger fever yet. Please consider carefully the many advantages of wireless $17 dollar triggers, with the triggers on the flashes powered by good old rechargeable AAA batteries. Will personally never go back to wired triggers again, even for a flash on a camera bracket. The RF603s are just too easy, and their range is super.

fabianbono: Basically, I don't want to loose any feature on the camera or in the flash.

Keep the flash swiveling and don't take out the tube then. Or consider dedicating a spare flash to becoming a trigger.

RussellInCincinnati: RF-603 can probably run fine off of a tiny bit of 5 volt POWER.

fabianbono: I think just use 3V inside from two AAA, is enough for current CMOS technology. But agree that can be powered on that way.

Getting the weight down to 38 grams for the RF603 is quite significant, since we are talking about attaching it to the little Sony flash. Similar considerations motivate me wanting to pull the big capacitor out of a modified flash as well.

RussellInCincinnati: Discard flash tube, the light output device. This "flash" is going to be just a radio transmitter now, it will never emit any light again.

Fabianbono: Here I suggest to add some resistor to simulate the bulb, and discharge the capacitor to complete the circuit functioning.

That would be elegant. Works well with my idea of using a much smaller capacitor, because the resistor would have so much less dummy power to dissipate. Have a feeling you are describing that we put a quite high voltage little transistor (not fun and scary to isolate from low voltage circuits) in series with the dummy resistor, so that when the flash signal comes, we drain the flash capacitor.

Am agreeing that a resistor in place of the flash tube (with series transistor?) would ever-more-perfectly emulate a flash tube. However my guess is that it isn't important to do so. Can't imagine that the Nex will care that, after the flash signal is issued, the flash capacitor hasn't after all been drained any. On the contrary, my guess is that the flash will, immediately after giving the fire-flash signal, just judge that hey, we're all ready to go again, immediately.

fabianbono: We don't know the chip inside flash what kind of controls make on the circuit.

True, but consider that the Sony flash circuitry must, like with any flash, deal with an extremely wide variation in capacitor charging times. The variation coming from depending on the state of charge and internal resistance of the flash's battery power supply. My guess is that a circuit that can handle both short and very long recharge times gracefully, will also react with graceful flexibility to ultra short recharge times. A recharge time of zero seconds being "ultra short".

RussellInCincinnati: A final power lead goes from the output side of the RF603 on-off switch, to just beyond the now-disconnected hinge switch in the flash, to become the main "flash" power as well.

fabianbono: We need to investigate, but need to care on how much current use the RF603, in order to save the camera battery, that will serve all the stuff!!

My guess is that the entire RF603 basically takes very little energy. Would appeal to your sense of logic, that whatever the RF603 takes, it is tons less energy than a flashtube requires. Also have never heard of a power supply that runs off a (once again highly variable) 3.2 volts or so of battery input power, that is so marginally specified that the RF603 would be blown away by the 5 volts coming from the Nex camera. My guess is that none of us would ever notice the current draw of the RF603 trigger in the great scheme of things.

Continued in next message 2 of 2...

RussellInCincinnati Veteran Member • Posts: 3,201
not *necessary* to kill the flash's output, 2 of 2

...

fabianbono: May be because we remove the flash (bulb+capacitor), that battery saving is the same to power the RF603. But better to confirm....Warning!!, be careful where you glue the RF603, since you need to continue accessing the RF-603 battery compartment to modify the small DIP Switch to change the Channels!!!

Yes, that is an argument for limiting gluing or attaching things (example a patch of velcro) to the RF603's battery compartment lid itself, and nothing else. So that the RF603 body can still be separated from the battery compartment lid.

Will also guess that the number of people wanting a radio trigger, and also want to continuously play with the channel settings of the radio trigger once they get it working, is small.

fabianbono: Again, here I don't totally agree on the idea to set permanent the Flash On mode to brighten the LCD screen, since you also ALWAYS will block some ranges on Aperture and Shutter speed on your camera. (Hell yes, the Sony firmware do that...) This give you less control on the exposure in my point of view.

Am not following this problem. Have not talked about doing away with a flash-on switch, we have discussed using the RF603's "on-switch" in place of the hinge switch . With the mods we are describing, if you turn the modified flash off, it "disappears" as far as the Nex is concerned, and you'd have back all your autoexposure modes.

Would pay close attention if you explained a bit further the problem you are foreseeing here.

In general remote flash is so complex, it has never occurred to me to take a single camera body, in a single session, and constantly reconfigure it between remote flash use and autoexposure non-flash use. Of course that's just me.

fototakas New Member • Posts: 21
Re: Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

Hi,

Good work, but my proposal will be to modify flash extender FA-EX1S, not the flash itself:

http://www.ebay.co.uk/itm/FA-EX1S-Sony-Alpha-NEX-FLASH-EXTENDER-case-/330693984744?pt=LH_DefaultDomain_3&hash=item4cfee5c1e8

Inside extender there is some space for the transistor, you just need to add PC sync port.

pmow
pmow Contributing Member • Posts: 821
Re: Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

fototakas wrote:

Hi,

Good work, but my proposal will be to modify flash extender FA-EX1S, not the flash itself:

http://www.ebay.co.uk/itm/FA-EX1S-Sony-Alpha-NEX-FLASH-EXTENDER-case-/330693984744?pt=LH_DefaultDomain_3&hash=item4cfee5c1e8

Inside extender there is some space for the transistor, you just need to add PC sync port.

Wouldn't the flash still fire? I'd rather have a tiny modded flash+trigger than a flash+trigger+extender...

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fabianbono
fabianbono OP Regular Member • Posts: 190
Re: Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

fototakas wrote:

Hi,

Good work, but my proposal will be to modify flash extender FA-EX1S, not the flash itself:

http://www.ebay.co.uk/itm/FA-EX1S-Sony-Alpha-NEX-FLASH-EXTENDER-case-/330693984744?pt=LH_DefaultDomain_3&hash=item4cfee5c1e8

Inside extender there is some space for the transistor, you just need to add PC sync port.

At first time, I plan the same.

But later I just don´t want to wait and decide to do it whit I have at home and learn the process!

It is true that you should have space for PC Sync port there, but until you don´t open the unit you can´t be 100% sure.

And in other side, I imagine that inside you only will found a slim flex to extend the connectors. So, will be very hard to weld the cables there. Believe me that is impossible to do it at the connector.

That is why I search the best place on flash flex board and use a magnifying glass and very tight pulse using the soldering iron.

And at last, you miss the standard ISO shoe mount to attach any wireless trigger.

Of course, these are my personal opinions! This is the DIY world, so you can do any version or mod you want!!!

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RussellInCincinnati Veteran Member • Posts: 3,201
clever idea. But preserve $35 flash with $37 extender?

fototakas: ...my proposal will be to modify flash extender FA-EX1S, not the flash itself: http://www.ebay.co.uk/...984744?pt=LH_DefaultDomain_3&hash=item4cfee5c1e8

Inside extender there is some space for the transistor, you just need to add PC sync port.

Am jealous for not thinking of this clever idea.

It is also true that you are describing spending $37 dollars or so for a physically unnecessary extender. So that you don't have to modify a flash unit that you probably already have, or can be purchased for around $35 to $40 dollars.

It has taken me some time to quit worrying about "wrecking" a piece of equipment that costs less than many lens hoods. We're making a $60-dollars-in-parts standard flash sync adapter, that's even a wireless sync transmitter at that . We're not trying to preserve an amateur near-throwaway flash unit (that happens to have a sophisticated microprocessor in it that can "tell" the Nex camera that there's a flash connected, etc).

The new point of view includes no worrying about wrecking the Sony flash, or wrecking a $17 dollar Yongnuo RF-603 radio remote flash trigger. Let's just chop the little flash and trigger up to get what we want in as small and as light a package as possible. Discard all unnecessary components like flash tubes, flash capacitor, RF-603 battery etc.

There are many reasons to get into the Sony flash unit if all you really want is a radio trigger adapter. Get rid of the big, relatively heavy capacitor in it that just sucks up power and delays the flash's cycle time for no reason. Disconnect and discard the fragile flash tube. By the way in discarding those components, now you are making plenty of room inside the Sony flash to put the new transistors and resistors needed make it trigger the RF-603.

Glue the Sony flash into the down position so that it doesn't flop around. Reroute the flash power so that it goes through the topmost RF-603 on-off switch, which becomes the master off switch for both the Sony flash and the RF-603.

The RF-603 already has a PC sync port on it, nice. Though for many folks, who cares really, the whole idea is to make a radio trigger. To perhaps another light weight, $17 dollar RF-603 which itself has a PC sync port, etc.

fabianbono
fabianbono OP Regular Member • Posts: 190
Re: clever idea. But preserve $35 flash with $37 extender?

By now, and until the stuff I buy arrives, I will just continue researching.

So I hope to come back for news in a couple of weeks, or may be just make the post for V2!

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perez69 Regular Member • Posts: 182
Re: Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

j13l wrote:

Great idea.

But, the use of an opto-isolator would be safer for the camera. (eg MOC3030 + a resistance for LED)
Some flash have high voltages. http://www.botzilla.com/photo/strobeVolts.html

Thank you for your search.

In this case how will change the circuit?

fabianbono
fabianbono OP Regular Member • Posts: 190
Re: Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

perez69 wrote:

j13l wrote:

Great idea.

But, the use of an opto-isolator would be safer for the camera. (eg MOC3030 + a resistance for LED)
Some flash have high voltages. http://www.botzilla.com/photo/strobeVolts.html

Thank you for your search.

In this case how will change the circuit?

The circuit is a little different.
Im thinking on do the V2 using some opto.

For your better reference, you can see this circuit that actually I modify my old Braun flash.

The optoisolator saves your camera and trigger the Triac that handle the high voltage.
Check this site.

http://www.carlmcmillan.com/Optoisolated_Adapter.htm

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j13l Junior Member • Posts: 32
Re: Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

Long ago (early 1980), I made a circuit to trigger a flash with the sound for water drop photography. I used a microphone, an amplifier and a MOC3033, and it worked well.

Here, the current source is provided by the NEX camera and the current of the LED will be limited by a resistor. (5mA)
The TRIAC(250v) MOC can directly trigger the flash. (check polarity)

To be verified.

perez69 Regular Member • Posts: 182
Re: Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

fabianbono wrote:

perez69 wrote:

j13l wrote:

Great idea.

But, the use of an opto-isolator would be safer for the camera. (eg MOC3030 + a resistance for LED)
Some flash have high voltages. http://www.botzilla.com/photo/strobeVolts.html

Thank you for your search.

In this case how will change the circuit?

The circuit is a little different.
Im thinking on do the V2 using some opto.

For your better reference, you can see this circuit that actually I modify my old Braun flash.

The optoisolator saves your camera and trigger the Triac that handle the high voltage.
Check this site.

http://www.carlmcmillan.com/Optoisolated_Adapter.htm

-- hide signature --

Thanks!
Do I need the SCR? My (mainly) use is to drive a wireless trigger.
If I attach a flash unit directly to the pc port do I need this SCR?

fabianbono
fabianbono OP Regular Member • Posts: 190
Re: Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

perez69 wrote:

Thanks!
Do I need the SCR? My (mainly) use is to drive a wireless trigger.
If I attach a flash unit directly to the pc port do I need this SCR?

This SCR mod is just to trigger old flash units that handle high voltage on hot shoe and PC Sync port.

If you will trigger only a wireless trigger all is ok, just a transistor or a single optocoupler.

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perez69 Regular Member • Posts: 182
Re: Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

fabianbono wrote:

perez69 wrote:

Thanks!
Do I need the SCR? My (mainly) use is to drive a wireless trigger.
If I attach a flash unit directly to the pc port do I need this SCR?

This SCR mod is just to trigger old flash units that handle high voltage on hot shoe and PC Sync port.

If you will trigger only a wireless trigger all is ok, just a transistor or a single optocoupler.

-- hide signature --

If I insert the transistor, can I use the same schema of the first circuit? Or should I change the resistors?

fabianbono
fabianbono OP Regular Member • Posts: 190
Re: Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

perez69 wrote:

fabianbono wrote:

perez69 wrote:

Thanks!
Do I need the SCR? My (mainly) use is to drive a wireless trigger.
If I attach a flash unit directly to the pc port do I need this SCR?

This SCR mod is just to trigger old flash units that handle high voltage on hot shoe and PC Sync port.

If you will trigger only a wireless trigger all is ok, just a transistor or a single optocoupler.

-- hide signature --

If I insert the transistor, can I use the same schema of the first circuit? Or should I change the resistors?

If you only plan to use wireless trigger, first circuit is ok.

If plan to use flash trough PC Sync port, is also ok, but more recommended to add an optoisolator.

In one or two weeks or so, I will receive my components, so will continue working on this version with optoisolator.

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pmow
pmow Contributing Member • Posts: 821
Re: Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

One of you wizards should offer your services in the commercial area...I'd love to get mine modded with a wireless trigger

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jurek_sz New Member • Posts: 10
Re: it's not *necessary* to kill the flash's output, 1 of 2

RussellInCincinnati wrote:

fabianbono: We don't know the chip inside flash what kind of controls make on the circuit.

True, but consider that the Sony flash circuitry must, like with any flash, deal with

The strobe capacitor charging control IC is BD4215. There are measurement circuit diagrams in catalog note, where Cmain is 2.2μF.

jurek_sz New Member • Posts: 10
Re: it's not *necessary* to kill the flash's output, 1 of 2

... and no tubes (I forgot to add).

fabianbono
fabianbono OP Regular Member • Posts: 190
Re: it's not *necessary* to kill the flash's output, 1 of 2

jurek_sz wrote:

... and no tubes (I forgot to add).

Do you have there the link of that IC datasheet?
I can't find it yet online.
Thanks
--
Fabian Bono
http://www.flickr.com/photos/fabianbono/show/

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jurek_sz New Member • Posts: 10
Re: it's not *necessary* to kill the flash's output, 1 of 2

fabianbono wrote:

Do you have there the link of that IC datasheet?
I can't find it yet online.

Try searching for "BD4215NUV"
(should appear first or second on Google)

jurek_sz New Member • Posts: 10
Re: Success PC Port output on HVL-F7S (Sony NEX) without PREFLASH!!!

fabianbono wrote:

SYNC signal is a kind of "shutter pressed" signal, instead of Flash Fire.

Does this mean that "rear curtain" mode is not available?

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