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There and back again: In-car timelapse experiments with CHDK

In Uncategorized on December 21, 2011 by Admin Tagged: , , , , , ,

Rain, plane and automobiles.

Here are a couple of timelapse video edits made from material I shot from in-car cameras, timelapse-enabled with the Canon Hack Development Kit (CHDK). The software is an amazing achievement and I use it regularly, although I only use a small part of its functionality. Installing it can be a bit fiddly and you need to spend some time with it, but I have found it extremely useful shooting timelapse and HDR.

Both videos were shot during car journeys that were at predetermined times so I had to accept the routes and weather conditions. One camera is on a suction mount on the inside of the windscreen on the passenger side. This position means that it is mostly in line-of-sight with the roof pillar and does not obscure the driver’s view. In the first video the other camera was mounted behind the passenger seat’s head rest, looking out of the rear passenger’s window.

Shooting through glass is always problematic, but there are ways of reducing the risks. Internal reflections can be reduced by masking internal features with blackout cloth, and/or mounting the cameras very close to the glass. Also, I use black cardboard masks to stop the camera seeing its own reflection. Cleaning the glass helps too. These two videos are just experimental and exhibit a lot of shooting faults.

I use CHDK on Canon Powershot cameras. I have several A560s and a few other models for various reasons. CHDK requires a different build of the software for each camera model so I mostly use several of the same model so that I can swap memory cards between them.

In unpredictable and and extreme conditions such as this, I mostly set the cameras to Program auto-expose and auto-ISO as it is impractical to change the settings during a shoot. This mostly works, particularly for video, as the movement hides a lot of the shooting faults.

I used the script Ultra Intervalometer and set the interval to 0 so the cameras shot as quickly as possible. This is about once a second for A560s. This depends on exposure time and they shoot slower in low light.

I performed various exhaustion tests on the batteries. I’m working on external battery boxes but running them on the two internal AA rechargeable batteries I get variable results depending on shooting period and interval.

Using fairly new Maplin 2,500 mAh rechargeable NiMH batteries (all numbers are approximate):

0 second interval – 9,000+ shots in about 4 hours.
5 second interval – 5,500+ shots in about 11 hours
10 second interval – 3,200+ shots in about 12 hours
20 second interval – 2,200+ shots in about 14 hours

To extend battery life I switch off the screen and this introduces a small problem that focus-lock is not preserved. This is not usually a problem for distant subjects but can be in some circumstances. Problems with the focus are apparent in the Jean Marc Calvet video, though not a big issue. When I’ve shot HDR timelapse, it is better to use external power so that I can lock exposure and focus in order to get higher quality results.

Canon Hack Development Kit (CHDK)
chdk.wikia.com/wiki/CHDK

The music for both videos is by Jason Shaw.
audionautix.com

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