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Archive for Sunday, September 13, 2009

Behind the Lens: Photography can create optical illusions

A paraglider flies past the wind turbines on the mountain of Schauinsland, southern Germany, in this AP photo that was published in Tuesday's Journal-World.

A paraglider flies past the wind turbines on the mountain of Schauinsland, southern Germany, in this AP photo that was published in Tuesday's Journal-World.

September 13, 2009

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Using a telephoto lens to create perspective compression and a choosing a unique angle for the framing, I created a photograph that has elements of an optical illusion.

Using a telephoto lens to create perspective compression and a choosing a unique angle for the framing, I created a photograph that has elements of an optical illusion.

I had a phone message at work Tuesday from an observant reader who believed the Journal-World’s Image of the Day on Sept. 8, page 3A, titled “Airborne obstacle course,” was doctored.

I quickly grabbed an issue to checked it out. The Associated Press photograph showed a paraglider floating by two wind turbines in Germany. It appears that the blade of the turbine in the photo’s background is overlapping the blades of the one in the foreground.

Knowing this is impossible, I suddenly figured the photo was a fake also. I went online to see the image in color for further inspection. What I saw there revealed more definition between the blades. They were not overlapping. The photograph wasn’t doctored but was simply an interesting optical illusion like in an M.C. Escher print. The photographer may not have even been aware of his visual trickery.

But the caller had questioned another aspect of the photo that made him believe it was faked. “They don’t put those things that close together,” he exclaimed. Indeed, the wind turbines’ proximity appears to leave no room for the paraglider to slide by without hitting a propeller.

But here is where the photographer purposely managed a magician’s sleight of hand. By using a long telephoto lens, he created something known as perspective compression. This gives the illusion of the two turbines being closer to each other than they really are.

I researched a little about wind turbine placement and found that a minimum spacing between typical turbine towers is about 810 feet, or greater than the length of two football fields. Even if these were smaller towers spaced closer than average, I’m betting there’s more than a football field or two separating them. The choice of lens and the photographer’s perspective created an interesting image.

In the photo accompanying this article, I also used the visual tricks of optical illusion and perspective compression. While it might appear that there is a person flying above a tree, it is simply an ice skater gliding across a frozen, snow-covered pond. The pond is Potter Lake, and to create the image I positioned myself on the hill above the lake. From this perspective, looking down on the scene, I could fill the entire frame with the pond, which I knew would appear like a bright white sky. I incorporated the tree and a small portion of the shoreline to ground the image. I then kept my telephoto lens framed on the scene and waited until the skater reached a point “in the sky” or further out in the lake where he had the appearance of being above the ground.

Having knowledge of your equipment and acquiring an eye for unique framing can provide opportunities to create your own optical illusions with your photography.

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