While reading the confidently self-assured comments surrounding stories like that of Klavs Bo Christensen and his images, which were recently disqualified from the Danish Press Photography Union Press Photo Awards for excessive photoshop manipulation, I have to remind myself that this intersection of technology, vision, culture, representation, and perception is torturously complicated. I've become a little weary of the many strongly worded, but optimistically simple statements about reality and photography, so I've started keeping an inventory of simple observations to explore this abyss of uncertainty. No perspicacious profundities, just some ideas to think about for perspective.
differences in the way I see a scene compared to what is captured in a photograph:
- My eyes have a higher dynamic range than both film and digital camera sensors.
- The border of my field of vision is not crisp and well defined.
- I don't see in black and white or infra-red.
- Moving things don't get blurry the way they do in a photo.
- On the other hand when things are moving very fast my eyes don't stop the motion—I can't see the individual blades of a turning propeller, but a photo with a fast enough shutter speed shows them clearly as though they aren't moving at all.
- The world is not flat; I see in three dimensions.
- The depth of field of my eyes is different than that of a photograph; I can never see an entire scene in focus when it involves objects close to my eye.
- My perceptual system is very good at filtering out insignificant objects that I am not focused on, but in a photograph those same objects become distracting.
- An object on which I focus can appear quite significant in the viewfinder, but appear surprisingly small in the print.
- Related to the above, a photograph does not capture the large moon illusion.
- When I tilt my head and look up at buildings, they do not appear to tilt backwards—my eyes don't suffer from a key-stoning effect.
- My eyes don't come in different focal lengths.
- White looks white under different temperatures of light, but film and digital sensors record bluer whites in shadows and yellower whites under incandescent light.
- My eyes seem to correct for a reasonable amount of atmospheric haze and other interference which reduces the contrast in a scene, but photos of the same scene appear washed out and dull.
Differences in the way my eyes record a scene and what I perceive:
- My retinas are not sensitive to color at the periphery, yet I see color throughout my entire field of vision.
- Each of my eyes has a blind spot where the optic nerve connects to the retina, but I see a seamless scene before me.
- Like film, my retinas capture light indiscriminately, but I don't normally perceive everything they record.
Differences between what I see and what I can measure empirically:
- Light has features that we can measure but can't see such as wavelengths outside the visible spectrum and the direction of polarization.
My color vision is trichromatic; my retinas contain three types of cone receptors that are sensitive to different parts of the spectrum. The interaction of these cone cells define the gamut of colors I can see. Through a genetic mutation some people known as tetrachromats have four receptors providing an additional channel of color information. Although not much is known about the perceptual characteristics of tetrachromacy, it is likely that these people see color differently than I do, just as I see color differently than people with dichromatic vision, also known as color blindness. Incidentally, many birds are tetrachromats with a fourth receptor that is sensitive in the ultraviolet range. The purple spot mantis shrimp (Gonodactylus smithii), with some of the most advanced eyes in the animal kingdom enjoys not only infra-red and ultra violet light within its visible spectrum, but it can also simultaneously see the direction of linear and circular polarized light.
- Illusions like the fraser spiral (above left) and the Müller-Lyer illusion (above right). There is no spiral in the fraser illustration—those lines that look like a spiral are actually concentric circles. I can't see them as circles even when I trace them with my finger. The Müller-Lyer illusion, although not as baffling as the fraser spiral is especially interesting because it is not universally perceived. It has been demonstrated people in some cultures don't see this illusion. It makes one wonder what else we think we know through direct observation that is in fact an effect of our cultural surroundings.