Design Elements

The design can be broken into four parts;

• camera
• controller
• rig and
• power

And at lest three interfaces;

• controller to camera (shutter/focus control)
• controller to rig (motor drive control) and
• human to controller (field programming)

These need to function together in order for the device to be useful on a shoot.

Camera

Ideally the camera used will be interchangable, with different camera interfacing cables available as required.  This should also enable multiple cameras to be fired at once, regardless of their make.

Controller

The rig and camera need to be driven by an autonomous device.  The most common solution is a microcontroller.  The most common microcontroller solution is the Arduino, however others are availabe.  Programs are written on a computer and then uploaded to the microcontroller via a serial cable (USB or RS232).

Rig

Various rigs could be contructed, as mentioned previously.

A focus on modular design should enable relatively simple interfacing, for instance the rig could be wired to accept logic inputs and power with onboard electronics translating the logic into pulses to drive stepper motors, servos, etc.

Power

Due to the variety of devices involved and their individual electrical requirements I beleive power supply deserves some consideration as an element in itself.

Controller/Camera interface

Assuming shutter and autofocus control is via a cable release with a push button, the interface can be done simply via an opto-isolator.  This isolates the logic and anologue circuits, protecting each device from the other.

Controller/Rig interface

A simple two wire output from the controller (direction/pulse) could be converted to stepper motor movement via another IC.  This logic would then need to be buffered through a transistor array to the motor coils.  This interface also needs to handle the voltage difference between logic and analogue input/outputs.

Human/Controller interface

The whole setup needs to be field programmable, in order to make changes to the program as required on location.  LCD screen(s) and buttons are probably the simplest way to get information in and out of the microcontroller, however other devices could be used.

Other Interfaces

As the design develops other interfaces may be required, such as light meters, vibration sensors, electrical compass, etc.