[Walky]

I guess most of you guys must know (of have experimented with) long exposure photography. One of the possible applications of this is what people call "light drawing" or "light painting", which consists on having a usually pretty long exposure picture "track" the movements made by one or more light sources (most of them moved by hand).

I was surprised to find out that no one seems to have tried this with their CNC machines, so I decided to try.

I remembered that I had done some (really crappy) long exposure stuff a few years ago, so I searched my old folders and found a few samples that might give you a good idea of what I'm talking about. That's me moving an LED keychain around.









This one is different, but I though it would be fun to show (change position, blink flashlight on my face, repeat...):





And now the CNC stuff, the brighter pictures had longer exposure times:


Who needs software based 3D toolpath previews when you can have real life toolpath postviews?


Work time was longer than expected, so I only got half the work on the first try. I got that sorted out later by carefully planning timings.







The light part is really simple, make of scrap parts I had around: just an LED, a resistor (10Kohm, so the light wasn't as bright as to brighten parts of the machine), some batteries and double sided tape to temporally fix all of it to the machine's Z axis. As you can see it's really on a budget, the good thing about this is that almost anyone with a CNC and a suitable camera can try it. I won't elaborate on the "DIY CNC how-to" part of this project since most people here already have that sorted out, and for the rest there's have an enormous amount of information on this forum which will outweight any kind of info I could possibly include here.




I used a quite convenient 3x AAA battery holder from an LED flashlight to supply power to the LED.


With some good planning it would be possible to do two sided drawings, and even use different colors.

What about "dot printing"?, turning the led on and off by software while building a volumetric image (a 3D camera would come handy, but hey!, we could just run the job twice, once for each eye, and just move the camera inbetween! (actually, this would for any kind of cnc controlled light drawing).
I bet anyone good with microcontroller programming could come out with a way to turn an image file into step/dir signals plus the correct PWM handling for an RGB led, so they could actually "print" a full color image pretty much like a CRT. Damn, what about doing that with a 3D model and a really high Z axis (I'm looking at you, RepRap/Makerbot people).

What about mounting the camera on the machine instead?

I'm looking at more stuff to do with it using parts I have around (budget is not really on my side this time), this thing has a lot of possibilities, really. I'm considering making some animations with this, making one frame at a time, then we'll see what it's like to put stop motion along with time lapse in a blender! How should I call this aberration?. I might as well make a looping animation, since a 10+ minutes setup/run time by frame means it will take a few hours to make a 30 frames animation.

The camera used was a Canon A560 with the custom CHDK firmware (this is actually needed to get longer exposure times with consumer-grade cameras).

Get it if you own a Canon point and shoot camera!, it's a crime not to.

CHDK Wiki


Any comments and suggestions are welcome!

[doorknob]

The creativity behind this is great...

You have reminded me that I haven't played with my CHDK-assisted camera in ages - I'll have to resurrect it ASAP...

[RomanLini]

That is very cool! Especially for something as simple as a LED a battery and a cable tie!

Thanks for the great photos.