Playing with Light

Light bottle

Light trail

The Christmas break this year gave me the opportunity to play around a bit with long exposure shots. The bottle picture on the right is the best of my experiments, and is a single 20 second exposure with minimal post-processing. The set-up was easy – just an empty bottle of wine, a darkened room, a blue wooden table, a tripod, and a blue LED penlight.

The idea was that once the shutter opened, I would move the penlight torch around the bottle in what would hopefully be a spiral shape. The movement produces the bright light trail, but also leaves enough light to illuminate the base and some of the bottle – in particular the label.

The trickiest part of the setting up is to determine the focus point. You can’t use the camera’s automatic focus as there is not enough light in the scene for the auto-focus system to work. While you could just switch to manual mode, on the basic SLR I used – a Canon EOS 350D – manual focusing aides are a bit limited. Instead I switched the main room light on, used the camera’s auto-focus to pick out the bottle, and then switched the lens to manual focus mode, being careful not to disturb the lens at all. I then killed the lights to start the shoot.

The next challenge is to determine good settings for aperture and shutter speed. This really is just down to trial and error. I decided upon f11 to try and retain a decent depth of field as the light circled the bottle. For the shutter speed, the main factor is how much time you need to move the torch through the air, while still leaving enough light to pick up the bottle. I also set the camera ISO to its lowest value of 100 to minimise image noise. Finally, setting the image type to RAW gave me more post processing control should I need it.

While the final 20 second image won’t win any competitions, I think it is quite cool. In fact, the blue enhances this! The photo has very little post processing applied to it – just a slight exposure tweak on the RAW file to brighten it up a fraction. But the experiment has given me some ideas to work on. For example, I would like to get a more symmetric light path as doing it by hand gave very wobbly and irregular results. But to do this I think I need to rig up some kind of pendulum for the light, and a smooth way of raising it up during the exposure. I also may try placing the bottle in a water-filled tray to see what reflection effects I can make.

Christmas Tree As part of the same photo session I took this photo of our Christmas tree. Again, I turned out all the room lights, leaving just the tree lights on as point light sources. I wanted to experiment with the effect of different apertures on long exposures.

This photo is using an aperture of f22 and a 30 second exposure time. I think the starbust effect on the lights is really effective, and is an artifact of the narrow aperture and the interaction with the optics within the lens.

The next image shows the difference between f11 and f22 on the same light. The narrower aperture really sharpens up the starburst effect. This effect is really worth considering when you are out and about taking night shots.

Effect of aperture

f11 vs f22

Shooting dark scenes with long exposures is certainly an interesting little photography project. In addition to trying to get nice photos, the need to switch to manual mode has the added benefit of really helping you to learn the subtle workings of your camera. Despite all the automatic modes that modern digital SLR’s provide, sometimes it is good to get back to basics and control everything yourself. Otherwise, why buy an SLR in the first place?

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2 thoughts on “Playing with Light

  1. Gosh Greg…it actualy sounds like you know what you’re talking about..I think the automated pendulum induced “smoother path” idea is the wrong way to’ll make the whole thing look too processed IMO…I like the wobbly effect…far more arty and authentic…

  2. Yeah, you could be right. Anyway, rigging up said device sounds like too much of a hardware problem for a software guy like me.

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