Flash/Camera Trigger Thing

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styrophil

Member
Just about got the following into a useable state. This is my first Picaxe project and, truth be told, I'm still working on various things but thought someone might be interested in the work so far. I'd be grateful for any comments and also if someone could come up with a better name!

One of the reasons for using a Picaxe and stripboard design was to make the unit simple enough for other interested photographers, with a little electronics experience, to make a similar unit.

Description

The unit is used to trigger either a digital SLR camera or flash when a particular event occurs. There are four programs in the standard setup, these are:

  1. Menu - Selects the program to run.
  2. High speed flash trigger - An IR LED/Phototransistor pair are used to detect the passage of an object such as a drop of water. On activation a delay is instituted and then the flash is fired capturing a photograph of the object hitting a target (normally a bowl of water). The above takes place in a darkened room with the camera shutter held open using the camera "Bulb" setting and a cable release.
  3. Interval timer - Allows a succession of photographs to be taken at a pre-determined interval. Up to 6000 photographs can be taken (depending on camera memory) at intervals ranging from 1 second to 24 hours. Photographs produced can then be combined into a time lapse video using Quicktime Pro or similar.
  4. Bulb Timer - Allows long open shutter photographs to be made without having to hold down a cable release button. Particularly useful for star trail photographs and low level IR photography.

The unit incorporates an external program download socket to enable updates and loading of new programs, a 16x2 character backlit LCD and 12 digit keypad.

Limitations...

  1. The unit does not work directly with some Canon flashes. This is a common issue with flash triggers and possible fixes are being investigated. The unit can still be used with Canon flashes but requires an external radio trigger.
  2. Timing for the Interval Timer and Bulb timer are achieved using the pause command and as such are only accurate to +-1%. Testing with the finished unit indicate a better accuracy than suggested but the unit should not be used for critical applications.
  3. Flashes with trigger voltages in excess of 400V should not be used.
  4. The delay for the High Speed Flash Trigger is adjustable in 10us steps but because of the processing overhead of the Picaxe chip there is an additional delay (yet to be measured) which would prevent the use of the unit with very fast moving objects such as bullets.

Here are some links

Picture of the unit without the sensor or camera/flash leads.
Zip file of the code - too much to put up here easily.
The circuit diagram in two parts. Part one and part two.
The stripboard layout
 
S

styrophil

Member
eclectic said:
Could you describe the Sensor arrangement
Click to expand...
I used an IR LED/Photo-transistor pair. I used the LED here and the photo-transistor here.

The LED/PT pair are mounted in a couple of bits of Lego, partly because it's easy to put together and partly because it's a reproducible construction medium. The front of the LED and PT are about 23mm apart.

The sensor construction is something I've got to finish but you can see a photo of the temporary unit here.

If you look closely you can see some cat hair stuck to the tape. Classy!
 
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Texy

Senior Member
Looks very interesting - I,d be interested in seeing a video of it in action.

So a drop of water going through through the 'tuning fork' is enough to cause a trigger?
You mention Canon - does it work for Nikon too?

Texy
 
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styrophil

Member
Texy said:
I'd be interested in seeing a video of it in action.
You mention Canon - does it work for Nikon too?
Click to expand...
I do intend to put together a video but I'm probably going to wait until September when I go back to work as I don't think my domestic video camera is going to pick up the detail.

Yes the sensor triggers the system with the passage of a drop of water. It's not perfect but it runs at better than 9 out of 10 hits. The main variation is due to the water droplet not always falling in exactly the same line.

I mentioned Canon because that's what I use but, yes it will work with other makes. For the flashes you need a standard hot shoe adapter. I've tested the unit with a Canon 540EZ flash (problems mentioned above) a Nikon SB24 and a Sigma EF-430 but I'll test more flashes as I go along. You need to use a hot shoe type flash (often called a speedlight or, incorrectly, a strobe) which has the option for reducing the power output. The reduction in power output is achieved by reducing the duration of the flash so you can get a very brief pulse of light and thus freeze the motion of the object. Studio flash units don't work in the same way so you can't use those. There are some specialist high speed flash units that give an extremely brief pulse of light but they are very expensive. You can hack something suitable out of a disposable camera flash but I don't like mucking about with them as they have nasty big capacitor bang capability, also you don't get any adjustable features.

To trigger the camera you need a suitable plug for the cable release socket. My Canon 350D uses a nice standard 2.5mm jack socket but most cameras have a proprietary socket. The simplest thing to do is buy an appropriate, cheap 3rd party cable release on eBay, cut off the switch end and solder on the a connector for the device.
 
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Texy

Senior Member
OK - thanks so far;)

Do you have any links or details on wiring the flash?
I don't own a seperate flash yet, but I,ll be looking at a cheap nikon unit.
I,ll also need to find out how to remotely trigger my Nikon D80.

Texy
 
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styrophil

Member
Texy said:
Do you have any links or details on wiring the flash?
I don't own a seperate flash yet, but I,ll be looking at a cheap nikon unit.
I,ll also need to find out how to remotely trigger my Nikon D80.
Click to expand...
There's no trick to connecting the flash. You just need a hot shoe adapter like this. Cut off the little plug and connect a 3.5mm mono jack socket. For use with the device it doesn't matter which way round the wires are connected but I would suggest that you connect the earth on the hot shoe adapter (That's the bit round the edge, not the pin in the centre) to the outer earth contact on the jack socket. I'm sure there's a better way of explaining that and I'll try to find/draw a diagram.

Connecting Nikon cameras is a more tricky proposition because there are several different versions of the camera connector. I think that the Nikon D80 uses a 10 pin connector and if that's correct you can find the details here. Scroll down to step 3. As I say just buy a cheap remote release from eBay and hack the switch end off and rewire.

I don't think that there's any such thing as a cheap Nikon flash. You might have a look at the Sigma units or go for something second hand if you don't need the dedicated TTL flash metering which is what I did. As an aside if you are considering a flash for your camera have a look at strobist.com and read the Strobist 101 section. It will improve the quality of your flash photography, just don't fall into the trap of thinking you have to use flash for every photo.
 
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Texy

Senior Member
styrophil said:
There's no trick to connecting the flash. You just need a hot shoe adapter like this. Cut off the little plug and connect a 3.5mm mono jack socket. For use with the device it doesn't matter which way round the wires are connected but I would suggest that you connect the earth on the hot shoe adapter (That's the bit round the edge, not the pin in the centre) to the outer earth contact on the jack socket. I'm sure there's a better way of explaining that and I'll try to find/draw a diagram.

Connecting Nikon cameras is a more tricky proposition because there are several different versions of the camera connector. I think that the Nikon D80 uses a 10 pin connector and if that's correct you can find the details here. Scroll down to step 3. As I say just buy a cheap remote release from eBay and hack the switch end off and rewire.

I don't think that there's any such thing as a cheap Nikon flash. You might have a look at the Sigma units or go for something second hand if you don't need the dedicated TTL flash metering which is what I did. As an aside if you are considering a flash for your camera have a look at strobist.com and read the Strobist 101 section. It will improve the quality of your flash photography, just don't fall into the trap of thinking you have to use flash for every photo.
Click to expand...
The D80 uses a small 4-way connector - I have a chinese wireless remote that I could hack into - either at the receiver end, or the transmitter end, I guess. Any particular reason that you used opto-isolators? I probably have relays spare, but I don't think I have any opto's.

Texy
 
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eclectic

Moderator
Texy said:
The D80 uses a small 4-way connector - I have a chinese wireless remote that I could hack into - either at the receiver end, or the transmitter end, I guess. Any particular reason that you used opto-isolators? I probably have relays spare, but I don't think I have any opto's.

Texy
Click to expand...
Sorry to interrupt Styrophil's thread.

1. I think that this is a cheap equivalent

http://cgi.ebay.co.uk/Remote-Shutter-release-Cable-Nikon-D70s-D80-RS-N2_W0QQitemZ110411587056QQcmdZViewItemQQptZUK_Photography_DigitalCamAccess_RL?hash=item19b50b1df0&_trksid=p3286.c0.m14

2. Relays will be MUCH too slow to operate.

3. When I played with Laser - interrupt triggers, I used 0.30pence isolaters.

I kept my expensive Nikon WELL away from any other voltages.

4. My Metz flashguns were ~17 volt. The opto's protected my Picaxe.

e
(with apologies to styrophil)
 
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styrophil

Member
eclectic said:
Sorry to interrupt Styrophil's thread.

1. I think that this is a cheap equivalent

2. Relays will be MUCH too slow to operate.

3. When I played with Laser - interrupt triggers, I used 0.30pence isolaters.

I kept my expensive Nikon WELL away from any other voltages.

4. My Metz flashguns were ~17 volt. The opto's protected my Picaxe.

(with apologies to styrophil)
Click to expand...
No apologies required - it saved me saying exactly the same thing.

I would add that some flash guns, mainly older ones, have trigger voltages far higher than the Metz. There is a rather good list here...

Eclectic what laser/receiving combination did you use for your experiment?
 
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eclectic

Moderator
styrophil said:
No apologies required - it saved me saying exactly the same thing.

I would add that some flash guns, mainly older ones, have trigger voltages far higher than the Metz. There is a rather good list here...

Eclectic what laser/receiving combination did you use for your experiment?
Click to expand...
Pic in posts 1 and 5 here:
http://www.picaxeforum.co.uk/showthread.php?t=12786&highlight=laser+tape

A cheap pen laser and a BPW34.

Got it working with a D200 and Metz 45-CL4.
(But never got it finished and boxed up, as you did.)

e
 
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styrophil

Member
eclectic said:
A cheap pen laser and a BPW34.
Click to expand...
Thanks for that.

I did use a BPW34 in an early version of the breadboard circuit but not in the final design because it meant ordering just one component from another supplier. I was trying to keep the number of suppliers to a minimum.

The BPW34/Laser combo does look like a good option for different sensor type. I'll have a go when I get a chance.
 
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Texy

Senior Member
eclectic said:
Sorry to interrupt Styrophil's thread.

1. I think that this is a cheap equivalent

http://cgi.ebay.co.uk/Remote-Shutter-release-Cable-Nikon-D70s-D80-RS-N2_W0QQitemZ110411587056QQcmdZViewItemQQptZUK_Photography_DigitalCamAccess_RL?hash=item19b50b1df0&_trksid=p3286.c0.m14

2. Relays will be MUCH too slow to operate.

3. When I played with Laser - interrupt triggers, I used 0.30pence isolaters.

I kept my expensive Nikon WELL away from any other voltages.

4. My Metz flashguns were ~17 volt. The opto's protected my Picaxe.

e
(with apologies to styrophil)
Click to expand...
Thanks e - remote cord purchased, and I also found the opto's.
Now I gotta find the flash unit. Missed one on ebay this evening - SB26 that went for £48, doh!

I,m figuring that I wont use my 28X2 for this project. I do have a 28X1 however - -how critical is the 28X2 running at 32mhz?
Actually sounds like an ideal project for the 20X2 when it comes out.
Also I'll not use the LCD driver chip - there is enough spare pins to directly drive the LCD in any case.
Texy
 
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styrophil

Member
Texy said:
Thanks e - remote cord purchased, and I also found the opto's.
Now I gotta find the flash unit. Missed one on ebay this evening - SB26 that went for £48, doh!

I,m figuring that I wont use my 28X2 for this project. I do have a 28X1 however - -how critical is the 28X2 running at 32mhz?
Actually sounds like an ideal project for the 20X2 when it comes out.
Also I'll not use the LCD driver chip - there is enough spare pins to directly drive the LCD in any case.
Texy
Click to expand...
£48 is a damn good price for an SB26

I think you could probably manage a direct connection to an LCD but I would guess that the problem you are going to run into is program space. You'll probably only be able to get one of the programs on board at a time.

As far as running at the higher clock speed goes the answer is yes and no. If you are only interested in using the unit to capture water drops splashing you should be fine but anything that requires a shorter delay will need the higher clock speed. Also running at 32MHz means that each instruction takes less time and so contributes less to any timing errors.

It is, of course up, to you and experimenting is part of the reason for being here but personally I think the X2 chip combined with the FRM010 gives you a lot more flexibility for only a few extra quid.
 
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styrophil

Member
Texy said:
WRT the flash hot-shoe adapter, to give me a bit more flexability, would I be able to use this option :

http://cgi.ebay.co.uk/Hot-shoe-Flash-tripod-to-PC-Sync-Terminal-Adaptor-UK_W0QQitemZ220438740719QQcmdZViewItemQQptZUK_Photography_DigitalCamAccess_RL?hash=item33532c3eef&_trksid=p3286.c0.m14
Click to expand...
You could use the above but you are going to have to find a cable that plugs into the unit and they are not the most secure plug/socket combination in the world. You are going to have a lot of cables, sensors, cameras and dripping bottles of water to line up all at once so you need to keep things as simple as possible.

I'd be inclined to go for this item, which is exactly what I have. Yes the tripod mount on the bottom is a very good idea.
 
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styrophil

Member
Two things I forgot to mention...

1) All the items for the project can be ordered from Tech Supplies and Maplin in the UK with the exception of the LCD and nuts and bolts.

2) You need to use a backlit LCD because you are likely to be using the device in the dark. I got mine from eBay here...

Oh and I've come up with a name - The Phifact - Programmable Hi Speed Flash And Camera Trigger.
 
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Texy

Senior Member
???! The eBay item I've shown does come with a pc male to male sync cable phil.
It's detachable as opposed to fixed as in your earlier linked option.
Texy
 
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Texy

Senior Member
Can someone explain what the 'trigger voltage' means for flash units? I thought this circuit is effectively shorting two pins to trigger the flash, not supplying any voltage at all? Its just that I,ve been looking at different flash units, and the trigger voltage is mentioned and varies from model to model.
Also is it important that the unit can act as a slave? Is this effectively what we are doing here?

Cheers,
Texy
 
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styrophil

Member
Texy said:
Can someone explain what the 'trigger voltage' means for flash units?
Click to expand...
You are not supplying any voltage to the flash unit at all. There is a voltage drop across the contacts of the flash hot shoe. When the flash is charged this can be anywhere between 2V and 400V depending upon the flash model. Full information can be found in the link above about trigger voltages in post 13.

Texy said:
Also is it important that the unit can act as a slave? Is this effectively what we are doing here?
Click to expand...
No that is not important at all for this application. The flash is not acting as a slave.
 
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Texy

Senior Member
Aaahh - I see, but we are also using those two pins to trigger the flash?
And the 'trigger' voltage is generated by the strobe and appears on these same two pins?

Texy
 
fernando_g

fernando_g

Senior Member
Texy said:
And the 'trigger' voltage is generated by the strobe and appears on these same two pins?

Texy
Click to expand...
That is correct.
In the old 35mm days, a mechanical contact was activated by the camera's shutter. On the flash unit, the trigger voltage was generated via a voltage divider from the main flash cap. Shorting it to ground caused a pulse to a trigger transformer, which triggered the xenon tube.

Nowadays, the camera "contact" is more likely to be the output pin from a microprocessor. It will be fried if it sees anything larger than its supply voltage. But also on the flash side, there will be another IC, that will compute the flashes' required output. This IC will drive an IGBT, that in turn drives the trigger transformer and later interrupts the xenon tube current.
So the interface is handled more or less at logic levels.
 
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Texy

Senior Member
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styrophil

Member
Texy said:
it doesn't work with a nikon D80
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I'm sure it will work with your D80 but only in manual, no TTL metering.

Having said that I don't think the SB24 you were looking at the other day would have given you the automatic metering either.

I think you might need an SB-600, 800 or 900 to get full TTL. Not sure about that and your best bet is to check on either the Nikon web site or one of the Nikon user groups on Flickr.
 
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eclectic

Moderator
Texy said:
...good price, but apparently it doesn't work with a nikon D80. I,ve read a review that its only good for film camera's. Thanks anyway - my search continues!
Texy
Click to expand...
No, it won't work at full TTL mode.

BUT, returning to Picaxe,
it could be a cheap way to provide a triggered flash,
in line with styrophil's original post in this thread.

And yes, if you want the full Monty,
the SB-600 works very well. But costs a little more. :)

e
 
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Texy

Senior Member
Whilst this thread has triggered me :)rolleyes:) into getting a flash for my camera, if I,m getting one I might as well get the best bang-for-buck and usefulness that my budget affords. So I could get an extremely cheap unit for this project only, or spend a bit more and get one with the features that the camera supports and that I,m prepared to spend. As it happens my local independant camera shop is listing a SB-27 for £50, which seems a pretty good price (no TTL metering, but out of my photography depth/knowledge anyway:D).

Cheers,
Texy
 
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styrophil

Member
Just a quick update...

I'm putting together some construction notes you can find the details at www.phifact.com

I've also booked the studio at work for next Tuesday so I can put together some setup shots and a video of the unit in action. (My kitchen doesn't make a very nice backdrop)
 
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Texy

Senior Member
Well I managed to win a SB-27 for £46, free postage;)

I also received the hot shoe bits, the remote shutter cable, and a few bits from Rev-Ed, including the IR diode and trannies. The opto-isolaters are at the post office waiting collection. I found that I already had a 2n3904 in my parts box, and also some other IR bits. This evening I got the IR circuitry working, although only on the breadboard, and not with any water:eek:. I can see that there's a lot of flexability with that 100k pot and the distance between the diode and receiver - I,m guessing it'll take a bit of experimenting to get it to trigger correctly, but all part of the fun!

Texy
 
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fernando_g

fernando_g

Senior Member
"I,m guessing it'll take a bit of experimenting to get it to trigger correctly, but all part of the fun!"

Exactly right my friend, that is so true.
And your IQ will have risen a little bit, too.
 
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Texy

Senior Member
First steps......

Started on the sensor today - here's a pic of my humble efforts :



I,ll probably use some heatshrink or something to protect the electonics from water;).

Handy tip of you don't know it - although IR is invisible to the naked eye, most camera's can pick it up. Here's a a shot of the sensor powered up in a dark room using my iphone :



The next quest is the camera trigger circuitry, as I now have all the parts required for this project - the SB-27 arrived today, and I also now have the opto-couplers.

Texy
 
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Texy

Senior Member
Phil,
can you confirm if this is the correct sequence of events for the high speed flash option:

In a darkened room.......
Set camera to bulb setting
phifact is armed
drop of water causes a trigger
after a selected time interval, the flash is triggered
(image is captured)
after a set time camera shutter is closed ?

Texy
 
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styrophil

Member
Texy,

Yes that's about it. I use a cable release on my camera so I can just hold the shutter button down and let it go when I have seen the flash fire, but I think that is what you are saying anyway.

I've just spent some time in the studio at work with my Phifact and I'll post some results later tonight or tomorrow.

Also used the Phifact to do a stop motion video of me tidying up the studio but that's processing away on the PC at the moment, not sure how it's going to turn out but I'll post up a link if it's OK.
 
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Texy

Senior Member
styrophil said:
Texy,

Yes that's about it. I use a cable release on my camera so I can just hold the shutter button down and let it go when I have seen the flash fire, but I think that is what you are saying anyway.
Click to expand...
....oh no, I didn't - I assumed that the phifact took control of the shutter, hence the connection to the camera?
Or is that for one or more of the other options? If thats the case, then I,m set up for all options, as I made the shutter cable today, although I,ve yet to test it, and I can still use my wireless cable release for the high-speed stuff (with bulb setting).
Texy
PS well done for the work on the website too - I don't know how you find all the time!!
 
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