Focal Power

A short film I found whilst browsing Vimeo this morning, I recommend watching in HD and with some boomy speakers:

Although the aerial shots would be interesting in themselves, the film has been manipulated to give the impression of ‘miniaturisation’ which transforms the film into a collection of enchanting scenes. The miniaturisation of these scenes provides an interesting contrast against the true scale at which power generation and consumption occurs across the planet. The poetically conceived caption for the video describes the scenes as ‘examined, microscopically, zoomed in from afar. Dimensions without scale.’

If you look at the film closely you will see that there is a short depth of field with a narrow band of sharp focus running across the image. This false ‘miniaturisation’ effect can be obtained through a method known as tilt/shift (although it usually only involves tilt) and can be produced optically using specialist lens adaptations or through post-production trickery. In essence, it works by employing the Scheimpflug principle in which the lens plane is ’tilted’ relative to the image plane (e.g. the sensor on a digital camera) and produces images similar to those taken at close range with a macro lens.

Usually the point of focus lies parallel to the subject, which means that objects which lie at the same distance from the camera all appear in sharp focus (in other words these objects lie within the ‘plane of focus’). By employing the Scheimpflug principle it is possible to orientate the plane of focus so that it passes through the subject creating a much shallower depth of field, which reduces the area of the subject in focus. This can be achieved by ’tilting’ the lens (for example upwards) which moves the plane of focus relative to the image and subject plane; a much smaller region of the subject now exists in focus. The diagram below illustrates how the lens plane is no longer parallel to the image plane after the lens tilt.

Image sourced from Wikimedia commons

If you were to shoot a high-rise building face on, with the camera parallel to the building you would obtain an image in which all of the building within the frame was in focus. When employing the Scheimpflug principle and the camera lens is tilted (e.g. upwards), the camera lens and building are no longer parallel. The lower portion of the building is now closer to the lens and the higher portions are now further away, this creates a shallow depth of field and as the plane of sharp focus is tilted the lower and upper portions of the building fall out of focus.

The photo I took below demonstrates the effect of which tilt/shift photography attempts to achieve. This photo, with its shallow depth of field, is taken at close range and involves objects which are very small in size.

Image of a Dor beetle taken in Wales.

Tilt/shift photography is able to recreate this ‘miniature’ aesthetic in much larger compositions such as those involving stadiums, cities and landscapes. These types of images are most effective when taken at a high-angle and can be shot using specialist tilt lenses or created by applying a false focal gradient in post production (simply with the selective addition of blur).

-Ed

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3 thoughts on “Focal Power

  1. Ah, so that’s how it works! I’ve been meaning to investigate what’s behind this effect for a while. There’s a really cool series of live-action stop-motion (?) tilt shift clips by an Aussie called Keith Loutit, which are also on Vimeo… messes with your head!

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