Sue and I just returned from a trip to North Western Pennsylvania. We set out to find fall color, a large waterfall, a 20,000 year old glacial boulder field, and a truly dark sky with no light pollution. Happy to report we found all of that in addition to a few surprises along the way. We even made a video or two at some very awesome locations. Stay tuned for those in the days ahead. In the meantime, I wanted to share the details from this photo above.
On the long stretches of Pennsylvania highway, it was the perfect opportunity to test this technique out. The idea was to illuminate the car interior with the flash while using a slow shutter speed to capture streaks of lights from passing cars. First I needed a stable platform, so I wedged my tripod into the back seat of our little Nissan Sedan. I then mounted the Canon 40d and 17-40mm lens with a Pocket Wizard connected to the camera's hot shoe. The Canon 580 EXII flash was then attached to the other Pocket Wizard and set to ETTL. I angled the flash head straight up and held it in my left hand. This illuminated the cabin of the car nicely. With the flash taking care of the car interior, I selected a long exposure time of four seconds for the traffic. In essence there were two exposures happening in the same frame.
Since it was very dark, autofocus was not reliable, and I opted to set it manually using Live View. This turned out to be a great solution as it allowed me to view the dashboard at 5x and 10x magnification and micro focus. With everything in place, we got on the highway and started to shoot. I would warn Sue of the flash with a 3, 2, 1 countdown. I used a cable release to squeeze the shutter. After about 12 shots I got one that I was happy with.
Safety First Note: If you should try something like this, please be careful as the flash can be distracting to the driver. The key is communication, so be sure to let your driver know each time the flash is about to fire.