Sensor-triggered photography

Hello fellow photographers,

I have built an arduino-based trigger unit, with sound, light, motion and range detectors. These can be used individually or cascaded sequentially. There is also an intervalometer and a water solenoid controller.

I would like to start a discussion regarding the possible uses to which this unit can be put. I've done the usual balloon popping, with spectacular results, and water drop collisions, and now I'm looking to expand my horizons. There is also an auxiliary input and, since I am an electrical engineer, I can devise any type of sensing device to trigger the unit.

Please take a moment to offer your thoughts on what can be done to take even more satisfying images with this device.

Thank you in advance

Lightning trigger - should be fairly easy.

Trigger to capture insects in flight. The idea is to use two crossed lasers, prefocus on the point where they cross and fire the shutter when both beams are broken. The mechanical setup may be more trouble than the electronics and software. A camera with very fast shutter response may help too. If flash is used, flash response time may be an issue.

Thank you for those suggestions Craig66. For the lasers I will have to use the auxiliary input, however that should not be a problem. The lightning strike should be straightforward.

You are aware of CHDK, no?

Nope. What is CHDK?

I read up on it and now I am aware of it, but don’t see the relevance, to be honest.

craig66 wrote:

Lightning trigger - should be fairly easy.

Trigger to capture insects in flight. The idea is to use two crossed lasers, prefocus on the point where they cross and fire the shutter when both beams are broken. The mechanical setup may be more trouble than the electronics and software. A camera with very fast shutter response may help too. If flash is used, flash response time may be an issue.

The most professional solution I have ever seen is this one:

https://petapixel.com/2010/02/05/photo-grandpa-shoots-with-laser-rigs/

https://www.flickr.com/photos/fotoopa_hs/5312347017

https://www.flickr.com/photos/fotoopa_hs/sets/72157604620957208/

https://www.flickr.com/photos/fotoopa_hs/albums

Have fun with those construction and the results!

Best regards

Holger

Thank you for that contribution Holger. What I had in mind is a lot simpler, but probably won't be as effective. I will keep you updated with how it goes.

You can write a script (or download a re-written one from the CHDK Wiki site) to use the camera's own image sensor to trigger photography...think lightning strikes, movement, or other parameters...

Turbguy1 wrote:

You can write a script (or download a re-written one from the CHDK Wiki site) to use the camera's own image sensor to trigger photography...think lightning strikes, movement, or other parameters...

CHDK is of no use if you don't have a Canon camera or if your Canon camera is a DSLR. There is Magic Lantern for Canon DSLRs. I have every respect for what these developers have done, but there are advantages in using external devices for triggering - easily adapted to just about any camera with probably no more than a different cable. You also have a wider range of triggering sensors at your disposal.

Thank you for that information; it is most useful. One of the beauties of my system is that the sensor responses can be cascaded sequentially, in any number.

Thx, for reference only.  Bookmark not working?

Piranha215 wrote:

Thank you for that information; it is most useful. One of the beauties of my system is that the sensor responses can be cascaded sequentially, in any number.

Not to be cute, but that's worked with CHDK for nearly a decade. I have fleets of PowerShots that I use that way, from $70 20MP ELPH180 to $130 16MP 50x Zoom SX530HS, with various internal/external triggering. Of course, I'm a computer engineering professor, so perhaps it's not shocking that I and my group are pretty good at this stuff.

Anyway, there is still value in having a good external controller, and an Arduino nano makes a nice sub-$2 plaform.

The key issue I'd be concerned with is release timing. Most digital cameras have significant delays from shutter trigger to shutter fire -- often between 1/100s and 1/10s. Using USB-power-sense triggering with CHDK, you can easily sync to within 1/1000s (which is the internal OS scheduling jiffy in the cameras), and with some work can usually hit within 1/30000s for trigger of the mechanical leaf shutter (which, incidentally, can do shutter speeds up to 1/10000s or faster on some cameras under CHDK). BTW, the CHDK motion detect code module examines the rear LCD live feed, so it has a max of around 1/24s latency to grab a frame from the live feed, but triggers almost instantaneously when it has the frame. Overall, this makes CHDK PowerShots excellent cameras for use with external triggers too; in fact, you could also have the camera OUTPUT a trigger to an external device using USB, camera LEDs, etc.

What detect-to-trigger latencies do you measure on the cameras you're using?  Which cameras?