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Anyone who has ever experimented with shutter speed knows that long exposures can yield some pretty interesting results. Whether it’s light painting at night or capturing the motion blur of a running river, long exposures can truly transform an image. A physiogram is a slightly different take on long exposure projects like light painting. It’s a technique that can easily be done in your living room, with no assistant required. Although the resulting images may look complex, the process to create a physiogram is actually very simple.
Physiography is actually a field of geography that studies the processes and patterns found in the natural environment. The name physiogram is apt because it is a photographic study of the patterns and movement of a suspended object. Imagine an object tethered to a string and suspended from a fixed point. If you push it, the object will swing around in a neat circular motion at first, completing each rotation in roughly the same place each time. However, as the object loses velocity, it will complete an orbit that is increasingly smaller than the last one.
The sequence of rotations that the object takes while it swings around isn’t visible to the naked eye. Fortunately, however, we can use photography to reveal these fascinating patterns. By attaching a light source like a flashlight or LED (don’t use a laser pointer – they can wreck your camera’s sensor!) to a rope or string and allowing the object to swing, we can view the entire path of the object in a single long exposure. The resulting photograph or physiogram reveals fascinating patterns and shapes.
Note: the tools in the Light Painting Brushes set can work as your light source for this and add color to your physiogram as well.
Take the LED and tie the length of string to it. Small LED lights on keychains are great because they won’t smash your lens if they fall. They also have a narrow light for better line definition and come with a key ring and chain for hanging perfectly vertical. You can usually pick one up at discount stores.
Take the other end of the string and attach it to the ceiling with a pin or hook. You want to fix the LED so that it will swing easily, about a meter and a half (5 feet) above the camera to start. Your camera will be positioned on the floor directly beneath the LED, so make sure each component is securely fastened. Having a UV filter fixed to the lens is a good idea, just in case something does drop on the camera.
To photograph nice clean lines of light, we will need to focus the camera on the head of the LED. This can be difficult when the camera is laying on the floor, and the LED is hard to define against the background of the roof. Instead, place your camera directly underneath the LED and place a piece of white paper beneath the camera to mark the spot (you may need to mark an X on the paper as your camera cannot focus on just white, it needs contrast). Then, take your camera and position it beside the hanging LED. Autofocus on the piece of paper and once it locks, turn the autofocus function off.
To start off, set your exposure time to 30 seconds at f/16 with 100 ISO. Position your camera beneath the LED, turn the LED on and turn out the room lights. Give the LED a good push, but be careful not to swing it so hard that it goes out of frame. Wait until the light settles into an even motion and press the shutter button.
Once your exposure is complete, have a look at the results! This project does require some trial and error to perfect, adjustments to your pushing technique, exposure time, and changing the length of the string or the light source are all ways you can refine the final image. A shutter release cable or remote trigger is handy too if you are experiencing camera shake.
Although you need a dark room to properly photograph a physiogram, you may find that part of the background still shows up in your photographs. This is caused by the light of the LED spilling around the room as it swings. The easiest way to fix this is by adjusting the black point in Photoshop. By adjusting the black point, you can reset what is interpreted as the blackest point in an image, without compromising the white light of the physiogram.
First, open your image in Photoshop and select Curves (in the adjustment layers panel or via Image > Adjustments > Curves). Click on the eyedropper tool with the black ink and the cursor will change to the eyedropper icon. Now click on an area in the background of the image, preferably a lighter tone that occurs consistently throughout the unwanted backdrop.
As soon as you click an area in the image, any tone up to the selected tone will be reset to read as completely black. It may take you a few tries to get the background uniformly dark (if you don’t like what it did, undo it click a different spot). This will also get rid of light fittings from your image as well as the hook that fixes the LED to the roof.
Once you get the hang of creating physiograms, switch it up a little! You can put layers of cellophane, glad wrap or glass over the lens for different textural and color effects. Change the light source, string length or zoom in and out during the exposure to create different pattern results.
This is a great opportunity to have fun and experiment, so enjoy! If you have kids they will love helping you with this project. Please give it a try and post your results in the comments below.