The people at [Hobby Robotics] decided to build a trigger circuit for lightning photography. There are more complex ways to do this, but they just used a photo transistor and an Arduino. The Arduino watches the photo transistor’s value and compares it to the previously captured one. If the difference is above a certain threshold, it means a rapid change in the amount of light has occurred, which triggers the shutter. An earlier post covered how to directly control the Canon 30d using an Arduino. All of this works because the shutter lag and code execution together are less than lighting’s 100ms duration.
dslr87 Articles
TI-83 Intervalometer
The headline How to Make Time Lapse Video With Your DSLR didn’t really grab us. Honestly, you pay that much for a camera and it can’t do time lapse out of the box? Well, we nearly missed the real story: [Chris Martino] was using a TI-83 to act as the intervalometer for the camera. The calculator has a 2.5mm audio jack for it’s data port and the camera has an identical port for the shutter trigger. The TI-83 runs a program with a FOR loop to act as the timer. When the loop completes it sends data to the port, and the voltage triggers the shutter. The rate isn’t very exact and varies depending on the charge left in the batteries. [Chris] estimated 10000 program iterations ends up being about 26 seconds between pictures. This technique has been tested on 84, 86, and 89 series calculators too. There are a couple example time lapse videos embedded after the break.
How-To: Expand Your Camera With CHDK
As anyone who has lusted over the technical specifications for Canon’s new Digital Rebel XSi knows, the capabilities of the average point and shoot camera are severely limited. Using the CHDK firmware hack, the features of Canon point and shoot cameras can be significantly expanded, allowing for ultra-high speed photography, very long exposures, time lapse photography, and RAW capture. This How-To provides a guide to our experiences using the CHDK firmware, and shows just how easy it is to get more out of a point and shoot than ever thought possible.
