Tag Archives: slow motion

I’ll stop the world

So, here’s a plan that I had the idea for ages ago, but only managed to assemble the relevant ingredients (a slam-door intercity train, a first class ticket, a daytime journey, some decent weather…) for this weekend.

In all my slow-motion work so far, I’ve used a static camera to capture a high-speed event. But, I wondered, what would happen if the camera was the fast-moving object? For instance, if you use a 210fps camera at 35mph, on playback at 30fps it’ll seem to the observer that they’re moving at walking pace- but everything observed will be operating at 1/7th speed.1

What I’d hoped to do was film the people on a railway platform from a train as it blasted past, but since the places they don’t stop at tend not to be listed in the timetables, this would be hard to co-ordinate. I figured that being at the very front of a fast train as it approached a stop would suffice; although the ‘frozen in time’ effect is less pronounced towards the end of the video, the platforms at non-stops tended to be mostly empty, so there’d be less to capture anyway. Helpfully, people don’t seem to move too much as their train arrives!

Here’s the most successful of my attempts, then- as it happens, the first stop, Bath Spa, had the best lighting. Youtube has, as usual, mangled things somewhat- it’s a lot smoother at the original quality, but vimeo does no better, so this’ll have to do.

Without a slow-motion camera you can achieve something similar by convincing a large group of people not to move! This improv-everywhere scene experimented with just that, which inspired a ‘big freeze’ flashmob in Edinburgh whilst I was living there. Portraying lack of motion in a photograph strikes me now as a fools errand, although like many others I did try, and the (annoyingly uncredited) photo in the BBC coverage is one of mine. The opposite problem, of compressing a block of time into a single frame, can give fantastic results, and is in some sense the inverse of what I’ve been trying here, which is to stretch a moment into an extended video. I find all this mucking around with time endlessly fascinating…


1 I’ve reworded this bit slightly as a lot of people have assumed the train was doing a mere 35mph- British rail isn’t that bad! I believe intercity services such as this can hit 125mph, although I don’t know whether they can build up that much speed between Bristol and Bath – or how fast you’re allowed to enter a station.

Water Balloons

Spring is slowly taking hold in Edinburgh, so I felt it would be good to take advantage of the sunlight and try some high-speed shooting outdoors. With a friend, Jaclyn, as glamorous assistant, I had a go at an old standard: capturing water balloons just as they burst. Caught at the right moment, the water retains the shape of its now-absent container before collapsing.

Burst 2a
(Flickr set)

It should be noted that sunny in Edinburgh needn’t mean warm… Next time I think it’d be a good idea to fill the balloons with hot water, as after a few soakings with cold water it’s hard to operate the camera! Still, at least the combination of 40fps and pre-record meant that we got the desired capture from each burst, although the shape and positioning wasn’t always ideal (I had hoped the balloons would be more spherical). The skin will end up on the opposite side to the puncture, so perhaps piercing at the bottom is best for a clear shot of the water- we discovered that simply dropping them onto a pin doesn’t work, however.

Bath Upchuck 2010


Created with Admarket’s flickrSLiDR.
Last weekend Gravity Vomit held a juggling and circus skills convention at the University of Bath (where I spent my undergrad years), so I headed east to the west country with the high-speed camera. The flickr set contains some individual grabs from burst mode, as well as a few experiments with capturing multi-motion images.

However, slow-motion video quickly turned out to be the real crowd-pleaser, so I concentrated on that: as well as the highlights reel above, there’s also a playlist of longer clips available on youtube.

Sublime


Created with Admarket’s flickrSLiDR.

My flatmate needed some dry ice for a vortex cannon demonstration which, even though we’re mathematicians, turns out to be surprisingly easy to get hold of through the university. In fact, she ended up with so much that I was able to use some of the excess for experiments of a photographic, rather than scientific, nature.

I quickly discovered that for seeing what’s going on, it’s better to add just a couple of pellets to plenty of water. That way you get to see individual bubbles of smoke before they burst – if you’re lucky, producing a smoke ring in the process. Carbon Dioxide is heavier than air, so it’s not a natural choice for smoke photography. But I did stumble on an approach that yielded an interesting set of abstract images. Placing a pellet in sufficiently shallow water prevents the gas forming large bubbles on the surface- instead, you get tiny streams of gas within the water, with the combined effect reminding me of magnetic field lines or iris patterns.

So what is actually going on here? I asked Dr Helen Maynard-Casely, the domestic scientist, for some insight:

These fantastic pictures are coming from the dry ice (solid carbon-dioxide) sublimating straight from its solid form to a vapour. This process of ‘cutting out the middle man’ (the liquid phase) happens when the atmospheric pressure surrounding it is insufficient to keep the solid together. When you expose molecules in dry ice to temperatures well above their melting point they vibrate: in the case of dry ice this is so vigorous that it is not contained by the air pushing in back. So instead of losing its crystal (solid) form and becoming a liquid the molecules fly off as a gas. The bigger the temperature difference the more vigorous the smoke will be (try putting dry ice in your tea….). Dry ice is only stable at -78°C so the large difference means you get more molecules flying off and a thicker ‘smoke effect’. Water ice often sublimates too, when sun shines directly on snow for instance. Also, this is how people who live in cold environments get their washing dry!

Sublimation may have also killed Napoleon Bonaparte. Arsenic also sublimates at the correct temperatures, and was used frequently as dye for wallpaper by British manufacturers in the 18th century. That was fine in Britain, where it was usually quite cold, but in a British-decorated house in St.Helena……

As well as photos, I captured a fair amount of slow-motion video too, which you can find in this playlist (the first few seconds of the first clip have unfortunately been mangled by youtube). For both stills and video, I was using a Casio Exilim FH20 camera, which is a bridge camera designed for high speed work. I’ve been playing around with this for several months, but was particularly pleased with this project: at high frame rates it suffers badly in low light conditions, rendering it all but useless indoors, so this time I borrowed a 500W floodlight which did wonders. So, not an expensive or sophisticated setup, nor all that complicated: camera stabilised on a tripod, either in super macro mode or manually focused, but otherwise making its own decisions about settings. Then it was just a case of sieving through 1300 photos and several GB of video for the best bits! Choosing between shots 1/30th of a second apart is near-impossible, but a set I’m happy with is up on flickr (and cycling through on the slideshow above).

Edinburgh Urbathon

Last week saw the first Edinburgh `Urbathon‘ – a 10K run with the added complication of obstacles and taking place in the less than flat Holyrood Park. The event was organised by Chest, Heart and Stroke Scotland as a fundraiser, if you’re wondering why anyone would subject themselves to such a thing on a Sunday morning, and you can donate online. I wasn’t competing, but probably racked up a comparable distance taking pictures and video- although not at pace! You can find a set of some of the better still captures on Flickr, and here’s the slow-motion video highlights courtesy of Youtube:

One of my shots also made it into the BBC’s Your Pictures of Scotland section this week, but the slideshow seems to be a bit broken…