External flash

kmitch

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Anyone tried to rig up an external flash? I am using the Fuji Discovery 90 camera and find the flash to be really weak. Somewhere on this website I've seen that it was only good for 9' which is about right. I was considering using an external flash mounted about 10" above the ground to illuminate the area better. I was planning on triggering the flash and the camera at the same time. Has anyone tried this? I know its's probably cheaper and easier to just get the Owl camera.

Keith
 

Tinhorn

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Somebody tried this a while back and did something wrong and toasted his camera :(

But, I don't think it'd be a real problem, I'd use a separate relay to trigger the aux flash.  The older 35mm cams had a "Hot Shoe" with a flash that attached to it, bet you could find a used one somewhere real cheap.   I think the Hot Shoe was just a switch because the Aux Flash had it's own batterys inside.

I seen some kind of Aux Flash at Wal-mart for $20 awhile back too

Tinhorn
 

Steve Jo

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Im thinking of doing this same thing, you can eliminate the problem of flash wash, you can get a superior flash that is powered from your main power supply, and you can use a cheaper camera with a substandard flash.  All huge plusses.

I think you should be able to get the timing right by comming off the wires that trigger the cameras flash and using them as triggers on an NO relay.  Essentially making your own hot boot.

I am goign to pick up the polaroid and try this when I get back home.

Any thoughts from the guys that are much smarter than me in this area, any obvious concerns?
 

Brian

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Everyone,

I have built some of these for my digital cameras because the ISO rating is so low on the cheaper models that I needed the extra flash for the pictures to look good.
I used a hot shoe slave mounted to the bottom of the external flash unit.  You can purchase the hot shoe off Ebay.  They run about 12.50 a piece.  The external flash unit I bought a walmart for about 15 bucks.  The unit was pretty easy to take apart and I just replaced the SPST relay with a DPDT relay that normally turned on the digital camera.  One poll was connected to the camera on button and the other was connected to the external flash unit.  One problem you will want to consider is that the external flash unit takes about three seconds to charge up to full capacity.  It will fire before this time frame but it will not give you as strong a flash.  That is why I used it with the digital camera system because mine take about 3 seconds to turn on anyway.

Hope this helps.

Brian
 

Steve Jo

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Brian, can you post a quicky schematic of the basic wiring?  Im a visual person :)

What is the delay right now on the Canon Owl? about 1 second?  can the flash charge be used someway to bias the trigger to the camera?

Would a larger power supply allow a faster charge?  The external flash has the versatilty of being run off the main power supply.

Good topic
 

Tinhorn

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I bet a cam that has a delay would be a problem because the time for the cam to go off and flash is not consistant but varies over cam  idle time.

I think an Aux Flash would not be feasible for an Owl PF or anyother cam with the flash charge factor, altho maybe something in the cam could be used to trigger the aux flash and get the shutter/Aux flash synchronized properly.

The Cheapo Point & Shoots would be ok tho and they are the ones who need the boost the most anyway......

Tinhorn
 

Steve Jo

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You can use the camera's flash trigger to set off the aux flash, then  the camera is dictating the timing, not the PIR.  Should be pretty simple.

I wonder if the PIR trigger can start the capacitor charge on the aux flash, then use the camera's flash trigger to set the flash off.  Its a short delay, maybe one second, but with a larger power source im wondering if that wouldnt be enough time to get an adequate charge to the aux flash?
 

horndog

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I seen on the web site that someone had a car headlamp attached to thier unit. Could be that you need to run another pir board for the lamp and not use a flash on the camera. Basically just make it so the lamp assembly runs off of 12 v instead of 110. This way you could buy the mainstay PIR and just modify it so that a car headlamp would go off and stay on for a certain period of time and then rest itself. One problem I see is that the deer would spook and run off and probably stay away for a few days. One good thing I see is the deer may think it is in a cars path and freeze, allowing a couple of pics to take before they get thier senses back.
 

Brian

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I don't have a way to send a picture right now.  I use the trigger signal from the PIR to trigger a one shot that is about 4 seconds long that pulls in a relay that simulates the on/off switch of the flash unit.  This gives the flash unit time to charge independant of the camera.  IF you needed it to charge faster I bet a larger power supply would help.  I use four AA's which is what the external flash was designed for.  I am not sure what value of power supply at six volts would be needed I haven't tried that.

Steve Jo is right because this is exactly what I am doing but with digital I did not have to worry about the time to charge because the digital took so long to turn on.

The external flash would have to charge very quickly to beat or at least get to a significant level of charge before the Owl PF/other cameras fired their flash.  The hot shoe Slave automatically will fire the external flash unit when the camera flashes.  So the only thing to figure out is how much power source is needed at six volts to fully charge the external flash within a second or so.  Maybe pretty large I don't know I have never tried this but sounds interesting.

Also, consider a daylight/dark circuit that will only allow the external flash to power up in daylight.  This will save battery power and be well worth the additional design cost.

Steve Jo:  you can build a oneshot out of nor or nand gates very easily.  They can even be built to trigger off the rising edge or falling edge of a 5 volt trigger pulse  this intern can be used to pull in a relay.  If I get a chance I will draw out a circuit and scan it and email it.  I posted some schematics on a digital camera some time ago with similiar style circuits integrated together.

Brian
 

Steve Jo

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So, if we cant get the external flash to hit an acceptable level of charge before the camera normally fires, we can use a NOR or NAND gate to bias the shutter trigger to the camera?

Signal flow something like this

PIR Trips -> Triggers flash charge -> flash charge triggers camera shutter -> camera shutter triggers external flash.

Even if we use a large power supply it may be necessary to configure it in this way to ensure adequate flash charge prior to trigger.  The larger power source will just serve to minimize the lag time bringing it more in line with where we are now with 1-2 seconds.
 

Brian

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The flash charge triggering the camera shutter would have to be based off time so this would not be an advantage.

Signal Flow

PIR Trips -> Triggers Flash charge -> time delay(based off power source charge time) ->Camera shutter -> Camera flash triggers External Flash automatically

This is the way mine works now except you could shorten the delay if you can shorten the charge time of the External flash.  I don't have a way to know when the flash is charged to full.  There is a light at the back of the exteran unit that comes on so if you could tap into that then you could use this as a trigger for the unit like you said but I haven't done this.

Brian
 

Steve Jo

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Didnt even think about the indicator light, that would probably be the simplest way to wire it.

I get home on Friday, Ill pick up a cheap external and start doing some time testing with different power sources.  I think it's really important to get the charge time down, but not at the sacrifice of shooting with less than a full charge.
 

dharter

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I had a car headlamp on my camera.  I found my 12V  5ah gel-cells drained of charge a few times so I stopped using it. An animal could have been hypnotized by it and kept retriggering it.  Also wet contacts may have shorted out the connector to the headlamp.  That is something that could be fixed.   I never could get the specs on current drain from the manufacturer.   I think I may have exceed ed the peak current drain rating of my battery.   When I tested my ms20 once it just started cycling on and off.  So I stopped using it so I could get more pictures.  
Here is an usefull link for making your own flashes/strobe lights.  You may be able to desing one that refreshes within a certian time interval.  Beware the voltage can be lethal!  http://www.repairfaq.org/REPAIR/F_strbfaq.html
Don't try to build anything unless you understand electronics and high voltage characteristics.
 

mole

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I dont know if this was considered, it comes off the CamTrekker page.

"Strobe Flash Accessory:
Double your flash distance so you can get better quality pictures of game traveling in low light conditions! The new Strobe Flash slides onto your CamTrakker and is triggered optically from the camera flash."
 

Tinhorn

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Good find Mole,

I thought I remembered seeing a slave flash that got activated when it "Seen" the camera flash go off but was not sure, my MemBrain just don't work all that good sometimes.......

Tinhorn
 

mole

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Just some random thoughts.

There are photo-slaves that trigger when they sense light. Mono-lights that photographers use have internal slaves. Radio slaves can be hard wired to hot -shoes and radio triggered to the external slave/flash unit. The problem again is how to get a quick charge before the first flash goes off. Slaves have their own power supply, most smaller units use 4 double As. But having it on the whole time would probably drain the jucie real quick.

I will talk to some photographers we have in our department and get more info.

Mike
 

horndog

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just curious if any one thought about using an external flash with thier homebrew setup. Would it be difficult to wire up to an owl? Some of these external flashes have a plug that goes into the camera, could these be used with a mono jack on the owl to trip the flash at the exact time or would this be to involved? any comments would be appreciated.
 

Tinhorn

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There was a post earlier about this, don't remember who started it or even the name but maybe you can search for "slave flash", I think that was used in the post text somewhere.....

The only one I thought would work was the type that sensed a flash (from the camera) then it flashed immediately.  

The reason I think this is the only feasable way is because of the Random Delay between the shutter press and the actuall flash caused by the flash circuit of the Owl PF having to charge up.  (if both the Aux Flash and Shutter are tripped simultaneously, the Aux Flash will Go Off then the Owl PF will Flash when the Re-Charge is complete)

But others disagreed and think other Aux Flash devieces can be wired up, I don't know if anybody got one working or not

Tinhorn
 

Brian

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I use the hot shoe slave attached to the external flash unit and it works fine.  I power up a relay that acts as if you turned the power on the external flash unit.  The hot shoe will sense the infrared pulse for auto focus that happens immediately before the flash occurs.  This way the external flash will always sinc with the camera no matter how long it takes the flash to charge in the camera.  The only problem you may encounter is that if the flash on the camera charges up faster than the flash on the external unit then you will not get a full flash out of the external unit.  I used mine with the digital units because it takes them about three seconds to power up and take a picture and that is right at the amount of time it takes the external flash to charge with AA batteries.

I use the Polariod External flash($15) unit at wal-mart with the hot shoe slave($12.50) off Ebay.

I can email some pictures of the completed unit.

Brian
 

Dbworld

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I saw one them inferior store-bought units at  Gander mountain that had a 90 foot external flash in it.  Can't remember what brand it was or all the features other than the flash.  I think it was $199, which I thought was pretty reasonable.
 


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