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10-01-2010, 05:59 AM   #16
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That sounds interesting, I've seen them on the net before but have been rather dubious of the results, if the shutter lags to much etc, and please if you get it fuctioning a guide on how to build would be great, so a 4 year old could understand....
But I think one of them would make day light lightning a lot easier, I have a few shots but its a real gamble during the daylight.

10-01-2010, 06:12 AM   #17
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QuoteOriginally posted by Ex Finn. Quote
Post your results when you get done with the build. I am curious about the delay times of the shutter activation and your home brew circuit.
You are hard-core, taking the route of transistors and not an op-amp..
Not a question of hard core or not.

Look at the requirements. We have to achieve a short circuit, or a low impedance any way, between two pins in the camera shutter release circuit.

The easiest way to achieve this is simply using a transistor.

By also adding a photo diode between collector and base, and using the available power from the shutter release pin of the circuit, any light that turns on the photo diode will bias the transistor and trip the shutter.

All you need to make this a reliable lightning trigger is to adjust the gain of the circuit by adding a variable resistor between the base and emitter of the transistor, which will shunt away some of the photodiode current, and therefore offer an adjustment for ambient light. the circuit is really really simple, and requires no power source,

Why should I use an op amp which needs power, when I don't need to?

As for lightning and reaction times, there have been many many published articles about this, and many lightning strokes last quite a long time, and are initiated by development of an ionized channel with stepped leaders, that work their way between the clouds and earth in 25-50 foot lengths, once the channel is formed there is then the full strike and usually a reverse strike or several restrikes in the same channel lasting some time.

the ~100mS reaction of a DSLR is fast enough for this. No need for bulb mode, and note bulb mode is hard on camera batteries, and also leads to heating of the sensor because it is powered for so long.

As I said, the concept works very well using a simple $15 flash slave, but it does not have the sensitivity necessary for lightning.

I may revisit this as I already have a slave to camera converter built. It is just a question of potentially modifying the slave unit.

Edit Note.

I have out of curiosity, taken the cover off my flash slave unit, and discovered, no surprise here, that the circuit is just as I have described, one transistor, one photo diode, and one resistor.

It would seem simple enough to replace the resistor with a potentiometer, to make the sensitivty adjustable.

Last edited by Lowell Goudge; 10-01-2010 at 06:57 AM.
10-01-2010, 02:41 PM   #18
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QuoteOriginally posted by Ex Finn. Quote
I should have said "old school". OP amps are easier to set up for gain and offset. Also, they are more forgiving to work with = harder to burn out.

Good luck with your build.

Cheers, Mike.
Mike

not a question of hard core, old school or anything else.

Unlike european engineering standards where the motto is "why do something simple when you can make it terribly complex?" I believe in the KISS principle. "Keep it simple stupid"

what you describe falls intop the former, but a photo diode, transistor and variable resistor are as simple as it gets and falls into the latter.
10-04-2010, 04:28 AM   #19
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Yes please do show us your results and a real easy how to guide. I have searched the net for home made lightning triggers and I'm affraid the "basic" that everyone seems to be going on about ain't so basic to everyone.(thats me)

As I've said I've searched the net but I seem to come across the same picture of the home brew lightning trigger, and I'm affraid it looks daunting.

After all my rambling heres my question, is there some websites I can read to get up todate so to speak ? I'm not sure which topic I stumbled on to but it mentioned photo diode , look heres a link to the page I keep getting:

Hobby Robotics Lightning Shutter Trigger for a Camera

And for me it's just not detailed enough or dumbed down so I could understand it.

I'd really like to make one , I have old vacumes and dvd players for parts what else do I need other than the knowledge ?

Please help, I'm getting wide screen eyes from steering at the monitor for hour and hours on end !

10-04-2010, 05:22 AM   #20
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QuoteOriginally posted by TeamPentax Quote
Yes please do show us your results and a real easy how to guide. I have searched the net for home made lightning triggers and I'm affraid the "basic" that everyone seems to be going on about ain't so basic to everyone.(thats me)

As I've said I've searched the net but I seem to come across the same picture of the home brew lightning trigger, and I'm affraid it looks daunting.

After all my rambling heres my question, is there some websites I can read to get up todate so to speak ? I'm not sure which topic I stumbled on to but it mentioned photo diode , look heres a link to the page I keep getting:

Hobby Robotics Lightning Shutter Trigger for a Camera

And for me it's just not detailed enough or dumbed down so I could understand it.

I'd really like to make one , I have old vacumes and dvd players for parts what else do I need other than the knowledge ?

Please help, I'm getting wide screen eyes from steering at the monitor for hour and hours on end !
looks to me a little too much overkill

the bottom line is you need a sensor, a photo diode, to detect the light from lightning. The secondary issue is that you need a means to determine what you are going to trigger on.

Note a simple flash slave is very simple, photodiode to detect light, a transistor to activate the flash trigger (in our case this will be the shutter trigger) and something to set the sensitivity of the system. what this link shows is that someone used a processor board to do all of this, which speaks volumes. It speaks of someone who knows software but not really hardware.

A flash slave unit will do the job just fine. See the schematic below. This is the actual schematic of a remote flash trigger, with one exception. The variable resistor shown is what I plan to install in place of the fixed one that is presently there. This resistor adjusts the sensitivity. If I replace it with a variable one,. then I can adjust it until the camera trips with ambient light and back it off just a little. then any increase in ambient light, including lightning, will trip the shutter.

The scheme works presently, I van trip the shutter remotely with a camera flash, it is just not sensitive enough.

No fancy PCBs, no software, just a simple modification to an existing $15 product.

Last edited by Lowell Goudge; 07-05-2011 at 06:59 AM.
10-04-2010, 07:58 PM   #21
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That sounds so simple, but in theroy it's way over my head, I've looked into building my own and people say I can attach it to a cable release and that would do the job but yet on the net I've found no instance of this, they all seem to need a pcb and a chip to program and the price over here for these items are too dare, I could buy a manufactured on from the States.
If you have any diagrams with your ideas that would help me a lot, I made my own cable release so if all I need to do is add those 2 items the transistor and the photodiode it would really help if someone could make a quick diagram so I know what I'm doing, I'd really like to be able to build one and hopefully get it to work, for my own piece of mind, (and my stress levels)

Thank you for all your comments tho, with the power of the people we all should be able to build one of these without to much trouble, I've looked around and it seems to be a topic of interest of many people may be we all can help out.
10-04-2010, 09:22 PM   #22
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Ok, so when I replied your diagram didn't load or I replied to quickly but thank you for the diagram, all I need now is to decode it, I know the Photodiode icon but I'm affraid the others I'm not familair with the others, but i'll have a look on the net.
So the zigzag line is the resistor, any idea what sort of resistor ? there is one for everything so which one is best or will do the job ? I have not found what that icon is with the dark black bent arrow , I first thougt it was a switch and now I'm not so sure.
I'm sorry to be such a pain but it's a project that I'm really invested in.
10-04-2010, 10:38 PM   #23
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I have used lightning triggers before and I have found them to be a waste of time, not to mention memory card space. the tried and true method of sitting and waiting with the shutter open has been the most effective for my work.

Pentax K7 ISO100 f/4 @ 30s


10-04-2010, 10:49 PM   #24
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And a fine result you've obtained, Sir.
Thanks for sharing.
10-04-2010, 10:58 PM   #25
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Yes excellent results

Now all you need is a direct hit and to get the DeLorean up to 88mph and we can all go back to 1985!
10-05-2010, 04:01 AM   #26
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QuoteOriginally posted by steve1307 Quote
Yes excellent results

Now all you need is a direct hit and to get the DeLorean up to 88mph and we can all go back to 1985!
10-05-2010, 04:14 AM   #27
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QuoteOriginally posted by TeamPentax Quote
Ok, so when I replied your diagram didn't load or I replied to quickly but thank you for the diagram, all I need now is to decode it, I know the Photodiode icon but I'm affraid the others I'm not familair with the others, but i'll have a look on the net.
So the zigzag line is the resistor, any idea what sort of resistor ? there is one for everything so which one is best or will do the job ? I have not found what that icon is with the dark black bent arrow , I first thougt it was a switch and now I'm not so sure.
I'm sorry to be such a pain but it's a project that I'm really invested in.
If you look at the diagram there are 3 components, the photo diode, an NPN transistor, and a variable resistor (the zigzag line and arrow in the middle).

This is the schematic of the flash slave, with the two outputs (comon and trigger) being wired to the shoe and shoe center contact respectively. Yhey are also wired to the sync plug to slave more flashes from the unit.

The stock slave comes with a fixed resistor which appears to be a 20K ohm resistor, I plan to add a variable resistor of 100K ohms in series to allow for some adjustment, This resistor is used to prevent some of the current from the photo diode biasing the transistor, and is how the sensitivity is controlled. it will be a trial and error process to get this working.

One thing you need to consider here is that you should have a basic knowledge of electronics so you understand the theory behind this properly, that way it will make explanations easier.
10-05-2010, 04:31 AM   #28
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even if you do manage to get a lightning trigger to work you will in all probability miss the shot anyway doe to the shutter lag present in most DSLR cameras at around 120ms with the average bolt of lightning lasting less than a millionth of a second.

the fastest digital camera I own is the Nikon D3 with a shutter lag of 40ms
10-05-2010, 04:32 AM   #29
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Very nice ideas here.. For my only one lightning photo so far I used the shutter button in bulb mode to open the shutter and close it after a lightning occurred, while holding the camera as steady as I could secures to the top of a fence post (did not have time to set up tripod). It took about 12 photos to get one keeper. Here in Florida, during the summer, isolated storms make it easy to capture lightning. It could be storming at the neighbors house and not rain at yours. The lightnings are majestic, fun to capture.

Last edited by agsy; 06-23-2013 at 06:04 AM.
10-05-2010, 05:17 AM   #30
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QuoteOriginally posted by Digitalis Quote
even if you do manage to get a lightning trigger to work you will in all probability miss the shot anyway doe to the shutter lag present in most DSLR cameras at around 120ms with the average bolt of lightning lasting less than a millionth of a second.

the fastest digital camera I own is the Nikon D3 with a shutter lag of 40ms
A single lightning stroke. on it's own has a duration of about 150 micro seconds, not the millionth of a second you imply, and thiis is not counting, the entire process of the development of the lightning bolt , or any restrikes etc. A lightning event can last several seconds from the initial flash.

There is an article somewhere that describes the entire process, including the formation of the conducting channel, the initial strike and restrikes.

but the point remains it is possible to trigger the camera from lightning.
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