The Shutter Speed of Our Eyes

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A plein air painting of a swift creek.

Since the advent of photography, artists have been intrigued by its possibilities. Some find it an indispensable component in their work, while others curse its intrusion. One thing we can agree on is that it has had a major influence on representational artwork. Even the devoted plein air artist usually has a trusty camera at their side. Its ability to record a variety of information has made it easier for us to work within the comforts of our studios. It often provides security to those who doubt their abilities. We tend to accept a photograph as fact whereas a painting is held up to greater scrutiny. Confronting this prejudice and acquiring a basic understanding of how photography compares to the human eye, can prove invaluable when attempting to produce representational paintings.

The mechanics of a camera are very similar to the human eye. The retina acts as the film or sensor in digital photography, recording information and processing it into recognizable imagery. The cornea acts like the camera lens, bending light rays through the pupil. The pupil and iris act like the aperture, controlling depth of focus. The missing component is the shutter: that curtain that lets a flash of focused light through the lens to the focal plane of the film. We actually see more like a motion picture or video camera, which is capable of recording a series of quick flashes into constant action, versus the one-shot camera. Vision is a continuous process with the blink breaking the sequence. Science has shown us that the average shutter speed for this human movie picture is somewhere around 1/50th of a second. We are also capable of quickly moving our focus, similar to panning with a camera. This helps to keep things that are in motion in focus.

When photographing subject matter that is in motion, anything slower than 1/50th of a second can appear blurred, while faster shutter speeds can stop action, creating too much detail. Since most handheld photography relies on a faster shutter speed than 1/50th of a second, we can ascertain that we are not really recording a human perception. Instead, the reference photo has stopped action and produced a frozen image. In the landscape this issue often arises when photographing running water. If the camera records the water at anything above or below approximately 1/50th of a second, an artificial appearing reference is produced. To test this, mount a camera on to a tripod for stability, expose a swift running creek at a shutter speed of approximately 1/50th of a second, then lower the shutter speed to 2 seconds, and finally raise the shutter speed to 1/1000th or 2/1000th of a second. The aperture will have to be adjusted to create a good exposure, which will alter the depth of focus. The appearance of the running water will be very noticeably different between each exposure.

It is not that these lovely reference photos cannot be utilized for inspiration and detailed information, but a degree of manipulation needs to be applied to make the painting appear real. As a dear painting friend once said, “We must record the scenes in front of us on the emulsion of our minds.” Our job is to harness the photograph as a tool, instead of becoming its slave.

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4 thoughts on “The Shutter Speed of Our Eyes

  1. Richard McKinley

    Patricia and Joe, Thank you for the comments. The eye and mind are truly complex. As useful as the camera can be, it can never replace a "human perspective". Another interesting comparison between the eye and camera lens is the depth of focus. The aperture of the camera shares a relationship with the size of our pupils. In dim light our focus is much narrower than in bright conditions. I plan to discuss this further in the future posts. Concerning instructional DVD’s, There are some new things in the works – in fact, I am in Cincinnati this week working on a couple offerings for F&W’s Artist TV and hope to do a plein air pastel demo with Artist Productions later next summer.

  2. Joe Drexler

    Richard,thank you for sharing all of your observations and ideas.I always learn something new from you and your work and have frequently referenced your dvd which in itself is a wealth of information.Just the other night my wife and I were discussing painting goals and the main theme centered around painting the impression mood or feeling of a scene with less detail and having the viewer instantly get it.This article helps me to further understand the difference between what I call "Paint world" and "Photo world".Thanks again,Btw do you have any plans for another pastel dvd? Joe.

  3. Patricia Lindley

    THis is a very insightful observation and one that bears remembering. It is hard to put one’s finger on why a faithfully rendered scene with massive amounts of sharp detail just looks wrong, and I think you have hit on the fundamental reason. I think it may be a little more complicated than just shutter speed… most of the visual perception magic happens in our brain, (this is how we get the moving picture integration of normal sight). We ‘attend’ to only a small proportion of the information that is actually received by our eyes. Our brain deliberate reduces the ‘resolution’ of information at the margins of what our focal point of interest is. So when we see a painting rendered in high detail across its entire surface (which may represent a large expanse of landscape) we are attending to details (because the picture is smaller in scale)in a way that we never would when viewing the landscape itself. This is also why these pictures just look odd… even if they are technically accurate.

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