Camera 1 remote for camera 2?

haleyfilms

3

« on: 21 / March / 2010, 15:35:11 »

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I am sending up two cameras, SD100 series. Camera 1 is using CHDK and two combined scripts, one for lightning and one for motion, to take pictures of the sun. There is a filter connected to camera 1, but there will not be for camera 2. They both have IR removed. Camera 1 will get less light than camera 2, therefore taking fewer pictures. I want camera 1 to tell camera 2 when to shoot so there are matching photos from both the primary and "control" camera. We want to compare the information with and without a filter, and identical shots that were taken simultaneously would be ideal.

Does anyone have any suggestions for this? I was hoping that a USB to USB signal could somehow be generated by Camera 1, and Camera 2 would be waiting for the signal to take the picture. I am okay with installing another set of software if needed, but a CHDK script would be most ideal. Please let me know if you have ANY ideas.

Thanks so much!!
-Ryan

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Microfunguy

4037

Re: Camera 1 remote for camera 2?

« Reply #1 on: 21 / March / 2010, 15:45:18 »

Welcome Ryan !

Yes, briefly blink camera 1 PRINT or autofocus led and detect with a photransistor.

That would be part of a circuit that then switches +5V to camera 2, operating in non-synch mode.

David

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haleyfilms

3

Re: Camera 1 remote for camera 2?

« Reply #2 on: 21 / March / 2010, 15:48:30 »

I appreciate you getting back to me.

So, a little re-wiring is necessary for this to work?
Basically, wire the LED from camera 1 to the trigger on camera 2?

« Last Edit: 21 / March / 2010, 15:57:39 by haleyfilms »

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Microfunguy

4037

Re: Camera 1 remote for camera 2?

« Reply #3 on: 21 / March / 2010, 16:34:34 »

Quote from: haleyfilms on 21 / March / 2010, 15:48:30

So, a little re-wiring is necessary for this to work?
Basically, wire the LED from camera 1 to the trigger on camera 2?

Well, there is a bit more to it than that.

If you do not know how, someone will have to make a circuit for you.

Alternatively, you could use SDM and clickPAN-SDM.

That provides a ready-made solution.

Although normally used to drive pan-and-tilt servos, you can drive a logic output high and low using a simple uBasic command.

Far cheaper if someone can make the circuit for you (and then use CHDK or SDM).

David

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haleyfilms

3

Re: Camera 1 remote for camera 2?

« Reply #4 on: 21 / March / 2010, 23:04:00 »

I appreciate you helping me with the idea. The circuit shouldn't be too bad, I am just worried about the extra power to run this thing. We are sending these up in a weather balloon, and the weight is very limited. We might just have to send them up taking seperate photos. I am not sure if we have the time to put togther a logic unit in a couple of weeks, considering other obligations and constraints. I certainly appreciate the ideas though, and I will present them to the team. You get full credit

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Microfunguy

4037

Re: Camera 1 remote for camera 2?

« Reply #5 on: 22 / March / 2010, 06:13:50 »

The power required is negligible.
The main thing is to make sure the phototransistor that you fit over the autofocus or PRINT led is well shielded from sunlight.

Basically, a resistor from a 4.5 to 6V supply is connected to the base of a general-purpose NPN transistor .. thus turning it on.
The collector of that transistor connects to the supply via a resistor and the collector also connects to the USB +ve connection.

So, normally the USB voltage is near zero.

The phototransistor connects from the other transistor base to ground.

When the led lights, the phototransistor conducts and pulls the other transistor base low .. hopefully low enough to turn it off.

The USB voltage rises to near the supply voltage and triggers the camera.

A convenient, small, light-weight source for the voltage is a tiny torch as sold by Frans :-

http://chdk.setepontos.com/index.php/topic,3631.msg33855.html#msg33855

+6V is OK on the USB connector, it is a logic signal, not a voltage that has to adhere to the USB specification.

This circuit can be made and tested in minutes.

The phototransistor must be securely mounted.

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