6 ms·

I make two products [1] that both use AVR microprocessors (though not Arduino), and both rely on sub-microsecond accuracy. One is a high-speed LED camera flash.

I make two products [1] that both use AVR microprocessors (though not Arduino), and both rely on sub-microsecond accuracy. One is a high-speed LED camera flash. The pulse width needs to be exactly the same every time, and so does the latency, otherwise the shot will be missed. The other is a sound trigger for flahes and cameras. That has to both be as fast as possible, but also exactly the same every time. If you're lining up a photo of a bullet passing through a cherry, you need to know that the bullet will be in the same position every time. Incidentally, I've written a post[2] about high-resolution timers with Arduino. The normal timing functions are not accurate enough for my sort of work, but the nice thing about Arduino is that you can easily drop down to the native AVR code, or even assembly if you need. [1] https://www.vela.io/ https://www.vela.io/ [2] https://www.vela.io/posts/how-fast-is-your-flash https://www.vela.io/posts/how-fast-is-your-flash

jevinskie 10y ago
This post made my day! High speed photography prompted my true diving into the guts of computers. It introduced me to C, in very raw way, by my use of the AVR Butterfly demo board. Prior to that I had only tinkered around with Perl/PHP/Java. I was able to get pictures like this [1] with a $25 microcontroller board (even cheaper now), about $150 in camera equipment, and a $40 pellet rifle. The setup was simple [2], with just a regular camera flash under a plastic bag (cheap diffuser!) and a configurable delay. The firing of the timer was controlled by the AVR's ADC readout of an electret mic. I ended up delaying about 20 milliseconds for the shots I took. [3] The AVR triggered the flash via an optoisolator relay. Pretty simple, I was glad to find out that even just placing a coin across the contacts will trigger the flash. Now I'm excited to measure how fast that standard flash really was, with your article's advice. And then, for the cherry on top, compare it to my General Radio 1531-AB stroboscope. [4] It was the cheapest externally triggerable stroboscope that I could find on eBay at the time. I got that flash because it can produce strobes as short as 0.8 microseconds! I really want to recreate an old high speed shot and see the difference between the flashes first hand. But college happened and I haven't touched photography in about a decade. I haven't even taken a darn photo with the stroboscope, I've just turned it on and soothed myself with the rapid and loud clicking. :P I hope your post motivates me! Your Vela One... so tempting... [1]: https://www.flickr.com/photos/jevinskie/115619170/ https://www.flickr.com/photos/jevinskie/115619170/ [2]: https://www.flickr.com/photos/jevinskie/112758047/ https://www.flickr.com/photos/jevinskie/112758047/ [3]: https://www.flickr.com/photos/jevinskie/albums/72057594084380014 https://www.flickr.com/photos/jevinskie/albums/7205759408438... [4]: http://www.ietlabs.com/1531.html http://www.ietlabs.com/1531.html
- ascorbic 10y ago
  Nice shots! If you do it again, you might find the AVR's analog comparator is a better route than the ADC. I use an external comparator on an interrupt pin in my sound trigger, which gives more flexibility. Perhaps I can tempt you further with a discount. Use the code HACKERNEWS for 10% off. That's open to anyone else reading this too, and is valid until next week.

jevinskie 10y ago

This post made my day! High speed photography prompted my true diving into the guts of computers. It introduced me to C, in very raw way, by my use of the AVR Butterfly demo board. Prior to that I had only tinkered around with Perl/PHP/Java. I was able to get pictures like this [1] with a $25 microcontroller board (even cheaper now), about $150 in camera equipment, and a $40 pellet rifle. The setup was simple [2], with just a regular camera flash under a plastic bag (cheap diffuser!) and a configurable delay. The firing of the timer was controlled by the AVR's ADC readout of an electret mic. I ended up delaying about 20 milliseconds for the shots I took. [3] The AVR triggered the flash via an optoisolator relay. Pretty simple, I was glad to find out that even just placing a coin across the contacts will trigger the flash. Now I'm excited to measure how fast that standard flash really was, with your article's advice. And then, for the cherry on top, compare it to my General Radio 1531-AB stroboscope. [4] It was the cheapest externally triggerable stroboscope that I could find on eBay at the time. I got that flash because it can produce strobes as short as 0.8 microseconds! I really want to recreate an old high speed shot and see the difference between the flashes first hand. But college happened and I haven't touched photography in about a decade. I haven't even taken a darn photo with the stroboscope, I've just turned it on and soothed myself with the rapid and loud clicking. :P I hope your post motivates me! Your Vela One... so tempting... [1]: https://www.flickr.com/photos/jevinskie/115619170/ https://www.flickr.com/photos/jevinskie/115619170/ [2]: https://www.flickr.com/photos/jevinskie/112758047/ https://www.flickr.com/photos/jevinskie/112758047/ [3]: https://www.flickr.com/photos/jevinskie/albums/72057594084380014 https://www.flickr.com/photos/jevinskie/albums/7205759408438... [4]: http://www.ietlabs.com/1531.html http://www.ietlabs.com/1531.html

ascorbic 10y ago
Nice shots! If you do it again, you might find the AVR's analog comparator is a better route than the ADC. I use an external comparator on an interrupt pin in my sound trigger, which gives more flexibility. Perhaps I can tempt you further with a discount. Use the code HACKERNEWS for 10% off. That's open to anyone else reading this too, and is valid until next week.