Two cameras connected and MD script to capture water drops. - Creative Uses of CHDK - CHDK Forum

Two cameras connected and MD script to capture water drops.

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Two cameras connected and MD script to capture water drops.
« on: 17 / November / 2008, 17:00:45 »
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Im trying unsucessfuly to photograph water drops with the MD script.
The script is fast enough for lightning but too slow for falling objects.
So I imagine a possible solution with two connected cameras. One near the origin of falling drops and the other, ready to shoot the splach, some centimeters bellow.
The first camera will act as a trigger for the second camera shoot.
Do you think that this is feasable?  Using SDM and a MD script?

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Offline Hacki

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Re: Two cameras connected and MD script to capture water drops.
« Reply #1 on: 17 / November / 2008, 17:08:50 »
You dont need to use SDM, as all stereo specific features of SDM are included in mainline chdk.

I guess its a problem with your settings. Maybe your MD script is not set sensitive enough.  A lightning is a quite huge increase in brightness, a falling water drop is harder to capture. Increase the sensitivity, decrease the number of cells which get compared, see if it works.




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Offline lrossel

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Re: Two cameras connected and MD script to capture water drops.
« Reply #2 on: 17 / November / 2008, 17:36:32 »
You don't need the stereo feature.

Just point the first (upper) camera down, with flash on and with MD script.
The flash of the first camera will trigger the second camera.
The rest is a matter of finding the right parameters.

Is a expensive solution, but I believe it will work.

Why you don't try just one camera, focus fixed to macro, and a sequence of water drops.

I'm sure you will get the camera triggered by the first drop, and the second one will be in focus.

You just have to find the right parameters, and a little bit patience.

Good luck.
« Last Edit: 17 / November / 2008, 17:39:27 by lrossel »
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Re: Two cameras connected and MD script to capture water drops.
« Reply #3 on: 17 / November / 2008, 19:10:46 »
Believe me. I have worked hard on this. Please do a simple experiment. Try to catch o golf ball with MD script. Hold the ball 20 centimeters from the lens and one ot two centimeters above so it not appears in the LCD. Let go the ball. The MD detects the move and fires the shoot. But the ball had already gone and is not in the photo. I test the MD script  and I got 40 to 60 ms response time. Its not enough.


« Last Edit: 17 / November / 2008, 19:13:24 by Microfunguy »

Re: Two cameras connected and MD script to capture water drops.
« Reply #5 on: 18 / November / 2008, 08:39:59 »
I think it should be possible to trigger the camera by using an inexpensive red laser pointer. Point the laser in such a way that the water drop will disrupt the beam as soon as it starts to fall. Use a small mirror (or even alu-foil) to reflect the (undisturbed) beam to somewhere in the FoV of the camera. Hopefully the disturbance of the laser spot should be enough to trigger the MD. With the MD reaction time of 100ms it should work (in theory).

 

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