Down to the action

As you probably noticed from yesterday's photo looking down along Odori Park, the Snow Festival stretches over a few city blocks. Twelve to be exact, with different sculptures and events on each block.

At the very foot of TV tower was my first stop - the skate rink. One of the wonders of digital photography is the ability to change your ISO on the fly depending on the light levels.

As soon as I got down here I needed a faster shutter speed to stop the skaters and so that required a faster ISO. In this case I got away with ISO 400 which gave me a shutter speed of 1/15 second. Not particularly fast you might say, but plenty for stumbling skaters.

That and a bit of flash. When you use a flash with a slow shutter speed you get a really interesting effect. The slow shutter speed gives you movement blur while the flash freezes movement. Many flashes have what's called second curtain sync. What this means is that the flash fires at the end of the exposure, rather than at the start which is standard.

So what happens is you push the shutter and the camera takes the photo (and the subject is blurred) and then just before the shutter closes again the flash goes off freezing the moving person. So you get a lovely combination of blur and frozen movement. By having the flash fire at the end of the exposure you ensure that the blur happens behind the clear, frozen part meaning that it's clear and easy to see. If you fire the flash at the start of the exposure your clear, frozen person gets covered over by blurry person making it very hard to see.

The other technique here is very technical - orange cellophane. The lights I was shooting under were a kind of halogen type which record an orangey colour in the camera. By putting a bit of orange cellophane over the flash you ensure that the flash fires at a similar colour temperature and doesn't look too out of place. If you don't gel the flash you get a big, ugly white light on the person and it just looks really weird.

The other point to look out for is the tree with the lights on it. The lights were flashing on and off and running through different sequences. It was really important to try and take a shot when the tree was well lit, hoping that that coincided with somebody photogenic coming in to the frame who moved at just the right speed to give a nice effect with the slow sync flash.

Who said documentary photography is just pointing and shooting?