Using the N900 as a remote flash

UPDATE: How-to now online here!

So, I want to take a picture of my bonsai tree, but it’s pretty dark, and flat lighting’s a bit boring:

But hey, some off-camera flash can make things look pretty exciting, if only I had a flashgun and some wireless triggers, I could get something like this:

Much better! But wait, with my oh-so-hackable N900 I can use that as a remote flash, by having it trigger its own flash and my DSLR at the same time, lets pull back a bit from the above crop:

Brilliant! Lets see a quick video of that in action to illustrate it, note the photo being taken appearing on the back of the SLR:

So how did I make all this work? Well, mostly cos the N900 is open source, linux like and easy to hack. It’s got an IR transmitter, and Nikon SLRs (a D40 in this case) have an IR receiver for remote shutter release. First a quick overview of what’s happening:

Shutter is a python widget that uses LIRC to trigger a Nikon remotely. Flashlight lets you use the N900s LEDs as a low power torch. Both are open source, so I can easily get the source, edit it and create my own program. What I did here was use some of the code from flashlight to instead of drive the LEDs as a torch, emit a short high-power strobe like when taking a photo. I then combined this with Shutter, so that the strobe was triggered at the same time as the camera. So I set the camera to instant remote shutter mode, click the widget on my N900, which then strobes the LEDs and triggers the camera.

Why would I want to do this?

..after all the N900 has a fairly weak flash, and you need to manually control the exposure on the camera now etc. Well, cos it’s fun. And taking photos should be fun. And now I can try out some fun photos with interesting flash. Just using my N900.

The codes a bit of a messy hack, but if anyone wants the source to try this out or develop the idea further into an app, post in the comments and I’ll get it online.

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