Snapshot is a Cheap, easy to use flexible timing module made specifically for taking high speed photographs. All you need is a camera with the bulb exposure setting, an external flash, and the SnapShot electronic trigger module. With SnapShot you can use a variety of triggers to fire up to three independent electronic devices (flashes, cameras, valves, etc.) at virtually any delay you choose. You can even set it up to do time lapse photography. Several flashes can be fired simultaneously from one Trigger. It has a 16 X 2 LCD display and Timers can be adjusted to be manual , sequential, or event based. Sensor input accepts digital or analog input.  Each trigger can generate multiple pulses, great for multiple drops or multiple exposures. Camera “Sync” mode to help make synchronizing the flash with your camera’s shutter. The device uses a PICAXE 40X2 microcontroller. An example of snapshot used for water drop photography is shown below.

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Water Drop Dispenser, Sensor and Trigger unit

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The Complete set-up, with DSLR camera, Flash, Bulb exposure and Snapshot.

When a drop of water is released from a height and made to fall on a bowl of water, the splash creates interesting shapes which can not be seen in naked eye. The shape of the splash changes with time. The whole process takes only few milliseconds. Capturing the shots at precise positions is always a challenge when one wants to do it manually. It is always hit or miss and takes lot of patience.

The process basically involves to control the release of drop, detect the drop that is released and timer that is synchronised so that the camera / external flash can trigger at precise moment.
So I went on to develop :
Drop dispensing unit
Drop detection unit
SnapShot

A studio type framework which can integrate all these devices.

Drop dispensing unit : This can release either one or two drops in successive intervals. You can adjust drop size and the gap between two drops. The control unit actuates a Solenoid valve to release the drop.
Drop Detection unit: I use an optical detector to detect a falling drop. This detector can be connected to a timing device which can start timing. Sensitivity can be adjusted depending on ambient light condition.

Snapshot : SnapShot can be activated either by the the release of drop or by the drop detector. The device is connected to the camera at Remote trigger port.

I use Canon 550D camera with 18 – 135mm kit lens or with 50mm FD Macro lens (manual). The shots are taken in manual mode and under flash lighting only. Freezing of the water drop happens by flash triggering. I usually trigger the camera with release of drop and trigger the flash from the timing device. I use three external flashes and these are synchronised through wireless triggering device. With intelligent flashes you can adjust the flash timing / flash intensity. Camera shutter remains open till flash triggers. Shots are normally taken under low light conditions. The trick is faster the flash, sharper the picture.

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The complete Electronic Setup for High-speed water drop Photography.

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Snapshot Controller Board using PICAXE 40X2 microcontroller.

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Few Sample photos taken using Snapshot.