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I've been looking to do some high speed strobe photography for a while, because the shots are cool and technically challenging. Last week, Bartel, my PI, told me that a dealer was in the Whitehead lobby trying to sell a strobe photo of a shattering vase of flowers for $22,000. He told me I should consider a career change.
So I decided to take that comment in the most positive light possible, and went and purchased a component kit from a teacher in North Carolina, who has some relatively simple trigger circuits and delay strategies based on the 555 timer IC. I actually got two circuit kits, one which is sound-triggered; the other is beam-break triggered. Decided to start with the sound trigger, since the possibilities are potentially more spectacular.
The ad-hoc timeline is something like this. Impact of something generates sound --> sound pickup goes through two transistors and triggers delay circuit --> delay circuit triggers my ebay flash transmitter --> two flashes go off. Meanwhile the camera (with 100/2.8 macro) is set to ISO100, f/11, 5" exposure. In my living room in semi-darkness, these settings pick up very little ambient light. What provides the light is the very very fast flash burst. I haven't measured its duration, but it should be much faster than 1/5000 second, which is the maximum shutter speed of the rebel xt (assuming zero shutter delay). Thus the "frozen" look of the photos.
The attempts from last night weren't that spectacular. What I really need is a place where I can leave a giant mess, and do shit like have a friend hit mini-watermelons with a baseball bat or something. Or a dry-ice bomb exploding. Or a shotgun and an expensive vase of flowers (please visit Whitehead Institute lobby for more details). Or LN2 and just about anything. Or cheap glassware being destroyed.
Back to the Bartel story. When he said this to me, I went and explained to him how such an image could be taken, and that in principle it wasn't let's say a year's salary's worth of amazing secrets to do. In fact, I told him, MIT has a 12 unit course in the spring, I believe from Course 6 (EE/CS), which teaches both electronics and strobe photography. How fitting that one would take a strobe course at the home institution of Doc Edgerton.
Bartel did not seem enthusiastic about letting me take a 12-unit photo course. Maybe he'll be ok with me taking the shorter intro course, 6.51s, which is a full-time, one-week workshop. They appear to make extensive use of bullets.
Anyway, I swiped a bunch of lab stuff and have been systematically destroying them in the dark.
First, credit due to Raymond, who drove me to Home Depot and helped me hunt down the pieces to build a pelxiglass enclosure to do all these experiments in (for <$15!!!). It consists of a large piece of scrap plywood, with three 1/8" plexiglass walls, and a hinged plexiglass roof. The thing works great. It lets me set up in my bathroom (no windows), let's say, an eppendorf secured with an adjustable wrench and filled with dry ice. I close the door and go do something else until the thing explodes, then hurry back to see the result. Meanwhile, pieces of shrapnel don't go flying everywhere (only in one direction). Another good application was balloon-popping. The balloon is filled with flour in order to make the pop more spectacular, and the enclosure keeps the flour cloud from drifting too much (which is why it is currently coated with white dust).
But the real highlight is the
destruction of borosilicate glass tubes with a slingshot and 3/8" BBs.
The original plan was to get a BB gun (and people still ask me why I
didn't do that). The simple answer is that BB guns either come as
serious BB rifles, or they come as airsoft guns. So airsoft guns are
interesting -- developed in Japan, where there are strict gun laws, they
are meant to allow a young, moderately wealthy, bored population of men
to act as if they were soldiers, swat teams, hit men, etc. Towards
this end, they are relatively good replicas of existing pistols,
submachine guns, assault rifles, etc. For a small additional fee, one
can purchase an airsoft gun without the bright orange paint that marks
it as a fake gun. I did not want to have to explain why I have an MP5
sitting on my dinner table while my face is planted on the floor. I
substituted a slingshot, which has considerably less reproducibility and
accuracy, but has other applications too -- like firing napkin balls at
people during group meeting.
All in all I had a
great time making these photos and practicing making these photos.
There are sheets of paper all over the place with a dozen BB-sized holes
all over them (as opposed to the center of them). I spent two nights
firing BBs at glass tubes and glass bottles in the dark (piece of advice
- don't try to destroy a winebottle with a BB slignshot. The glass is
thick and the BB just bounces off. That one nearly brained me). The
only problem is that now there are large pieces of broken glass inside
the enclosure, and tiny shards on the floor everywhere that I keep
pulling out of the soles of my feet, even though I've vacuumed the floor
three times.
To remind him of his advice to
me, I left an 8.5x11 print of the cover photo here in Dave Bartel's
in-box. He was suitably impressed. Sue-Jean and Huili also took a
print down to the Whitehead lobby and hung it up next to its $22,000
sibling. The photo lasted a day before it was taken down by public
affairs, but rumor from Dave is that they want to put it back up and
publicize it somehow.
For the future, we've got
to figure out how to make something explode without dry ice. The
problem right now is that the dry ice cools the inside air to below the
dew point, so that when the tube explodes, there is an instantaneous
cloud of condensation that obscures the exploding tube. Have tried
using backlighting to mitigate, to no avail. On the other hand, the
condensation plume that develops when the cap is allowed to pop is
pretty cool.
