Saturday, March 1, 2014

Experiments in movement

I last wrote about the trigger kit that I assembled with a friend over a couple of weekends.

This weekend I finished a second trigger sensor - the one that reacts to sound.  Of course once I had done this I spent Friday evening trying to capture a balloon bursting.

Even with the shortest delay, the force of a balloon bursting is so great that I was not able to capture the balloon with no motion.

I also completed the soldering of a flash trigger so that now the kit allows me to use remote shutter or a flash trigger.

I used the flash trigger for the balloon photographs thinking that I'd get better speed from the flash of light than from the shutter speed.  This meant working in a dark room with a few second's exposure and  letting the duration of the flash light take care of freezing the action.

I read somewhere that the regular speedlite flashes produce a burst of light that can go up to 1/50 000th of a second which is considerably more than the fastest shutter speed of the camera (1/4000th of a second) but I guess I should have done more research on this because even when I reduced the power of my flashes they were not able to stop the balloon in motion.

The few times the balloon was caught in frame did create interesting effects but I am really looking to freeze the motion completely.  The web site that I bought the trigger kit from has a manual that I am going to have to read to get more information on this.

After (running out) giving up on balloons I went back to experimenting with the sound trigger/remote shutter release combination with light bulbs.

I remembered once seeing a bare light bulb get shattered in a storm when water was blown onto it and I imagined that the popping sound of a bulb breaking like that could be a worth exploring with the kit.

During the week I had bought a few small appliance light bulbs and experimented with breaking them with drops of water.

The first try resulted in little more than a fizzle and the bulb filling up with smoke as the air came into the vacuum through a crack.

I realized that I needed more than a few drops and had some success dropping a large spoonful of water from a cup onto the hot bulb.  Of course there are all sorts dangers inherent in using water near electricity like this so I don't recommend that you try this at home!

As the glass breaks, the air coming into the light bulb usually causes the bulb to flare and does give a loud enough pop to trigger the sensor.

I got a few really satisfying images from this experiment before giving up for the night.  It turns out that for these photographs the sensor and trigger are more of a convenience than a necessity.  It allows you to work alone setting things up and taking the images.  I think that you could as easily capture these with a willing assistant.

One thing that is key with the light bulb is getting the exposure right so that the camera is not overwhelmed by the light.  This is fairly simple - you just expose on the lit bulb as if that is all you are photographing.  In my case I also had flashes that fired to light up the bottom of the bulb.  The photograph below was taken without flash.

I was also frustrated during the balloon experiments because the "instant" trigger switch wasn't working on the gizmo.  I was only able to use the trigger that has a delay between the sensor activation and the camera or flash trigger being fired.  I opened up the box to see if I could figure out what was wrong in there.  After examining the photographs on the web site with instructions, I discovered that I (oops) had not soldered the wire from that switch to the board - in fact it was tucked in and not connected to anything!  Another demonstration of how miraculous it is that it worked at all!  Imagine if the loose wire was critical to the central components!

After fixing that this morning I was back using the photo gate trigger.  I was curious about the distance that the trigger can tolerate between the sensors.  As they are wired, they end up being pretty closed together but by making them parallel I was able to point them at a mirror and get a much wider area through which I could drop larger objects than the ice cube in my original experiments.

So I pulled out a rather uninteresting casserole disk (I guess I am going to have to find something a little more elegant) and brought an apple and an orange to the party


  1. The link you provide is most useful since it mentions "fooling" the automatic setting of a flash by setting a large aperture to shorten the time

    1. Going to have to keep experimenting. This is a lot more fun than the hit and miss of burst mode shooting. It is easier to adjust timings etc.