Oxford School of Photography

insights into photography

Cameras vs the human eye

I was teaching the first session of our Understanding Your DSLR Camera last night and in encouraging the students to explore their subjects and not to just take a picture from their standing position set me thinking about the difference between the human eye and a camera. Why can’t we just point a camera and capture what we see, how hard can it be? I am often told by those new to photography that what their cameras reproduce is not what they see so why is that. Doing a bit of research I found my way back to the ever excellent Cambridge in Colour website. This has to be the most technically correct site on photography, the detail and explanations are precise as a very precise thing, say an atomic clock….Here is a short bit of what is explained, go here for the full detail with pictures and diagrams, it is interesting

Dennis_Stock+_camera_eyesPortrait of Dennis Stock by Andreas Feininger

Our eyes are able to look around a scene and dynamically adjust based on subject matter, whereas cameras capture a single still image. This trait accounts for many of our commonly understood advantages over cameras. For example, our eyes can compensate as we focus on regions of varying brightness, can look around to encompass a broader angle of view, or can alternately focus on objects at a variety of distances…….

Our central angle of view — around 40-60° — is what most impacts our perception. Subjectively, this would correspond with the angle over which you could recall objects without moving your eyes. Incidentally, this is close to a 50 mm “normal” focal length lens on a full frame camera (43 mm to be precise), or a 27 mm focal length on a camera with a 1.6X crop factor. Although this doesn’t reproduce the full angle of view at which we see, it does correspond well with what we perceive as having the best trade-off between different types of distortion:…….

Most current digital cameras have 5-20 megapixels, which is often cited as falling far short of our own visual system. This is based on the fact that at 20/20 vision, the human eye is able to resolve the equivalent of a 52 megapixel camera (assuming a 60° angle of view)……

Taking the above into account, a single glance by our eyes is therefore only capable of perceiving detail comparable to a 5-15 megapixel camera….

Overall, most of the advantages of our visual system stem from the fact that our mind is able to intelligently interpret the information from our eyes, whereas with a camera, all we have is the raw image. Even so, current digital cameras fare surprisingly well, and surpass our own eyes for several visual capabilities. The real winner is the photographer who is able to intelligently assemble multiple camera images — thereby surpassing even our own mental image.  Go here for the full article on Cambridge in Colour

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