Archive for the ‘Arduino’ Category

Microsecond air-gap flash photography

Sunday, October 2nd, 2011

To take photo’s of really fast events, you need a very short duration flash. A normal camera flash lasts about 1-3 milliseconds at full power. These pictures were taken using a home built microsecond flash, a thousand times faster.
Example: a bullet travels at 1000 feet per second (305 m/s), so in 1 millisecond it would be blurred out to a 1 feet (305 mm) long blur. Using a microsecond flash, the blur would be 1/1000 of a feet or 0.3 mm.

This card deck is incomplete now (AR15, 9mm bullet)

No flames like .44 magnum flames

Bullet just left the S&W 686 .38 Special at about a 1000 feet per second.

A classic: 1911 makes for a messy shot

Microflash has more "stopping power" than a hollowpoint. Measured at 329 m/s or 1184 km/h using a chronometer. It rotates at 80120 RPM, once ever 9.7 inch.

Small balloon collapses very fast, even compared to bullet speed.

Chronometer showing 9mm hollowpoint speed in m/s (1080 fps).

Another balloon hit.

.177 pellet exiting the muzzle of an air pistol

Soap bubble hit by pellet

The air-gap flash was built from readily available scavenged and new electronic components, very similar to the EG&G MicroFlash 549.
The flash was triggered by an Arduino microprocessor with user selectable delay of about 1 millisecond using a piezo microphone to detect the shot.
Main inspiration/information for (and warning against) building a similar flash unit can be found here.

Complete flash system with tubular flash housing, Arduino in a control box and microphone.

Flash stripped from drain tube showing from left to right: spark gap, capacitor, trigger bobbin, trigger circuit and flyback driver.

Business end of the flash

Close-up of the 20mm spark gap and trigger wire.

Arduino triggered lightning photography

Tuesday, June 28th, 2011

- Arduino
- a simple photodiode
- a cheap shutter release remote cord from Ebay to get a plug for the Nikon D90 remote port (2.60$)
- a major thunderstorm after sunset

- DSLR set to manual 1s exposure time, diaphragm wide open , ISO low
- Arduino waits for light flash detected by phototransistor
- On the detected light flash the port connected to the remote cord goes LOW
- Shutter opens after 69 ms (that is the Nikon D90 shutter lag)
- since lightning is not an instantaneous event you still catch the final discharge and/or afterglow