The Atlantic: How the 50-mm Lens Became ‘Normal’, by Allan Daigle

https://www.theatlantic.com/technology/archive/2018/05/how-the-50-mm-lens-became-normal/560276/

“… One lens in particular—the 50-mm lens—is often seen as the most objective of objectifs, and it is said to be the lens that best approximates human visual perspective. For example, the precision-lens manufacturer Zeiss states that its Planar 50-mm lens is “equal to the human eye.” Many artists have taken up 50-mm lenses to render ordinary, everyday experience….

… But the concept of “normal vision,” let alone the 50-mm lens’s ability to reproduce it, is hardly a given. The idea that a 50-mm best approximates human sight has more to do with the early history of lens production than any essential optical correspondence between the lens and the eye….

… Perhaps the 50-mm communicates an anxiety about whether an individual can understand someone else’s vision. Under the right circumstances, a 50-mm lens does create a perspectival relationship that, more or less, approximates the ways the majority of people see their everyday world. But it’s still relative….”

Commentary

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The legendary Minolta CLE 35mm analog film camera with 40mm f/2.0 perfect normal prime lens, photograph courtesy of Japan Camera Hunter.

The relevance of 50mm focal length in 35mm sensor format being “normal” or “standard” has long been in dispute with opponents often pointing out that the mathematical  definition of “perfect normal” in that sensor format makes it closer to 40mm, hence the 40mm “normal” lens supplied with the Leica CL and its successor, the Minolta CLE.

Viewing the world through the narrower 50mm focal length appears to be more a matter of habituation than human biology, as I deduced many times over when teaching art students new to photography.

Human binocular vision is capable of encompassing a view over 180-degrees when staring directly ahead and without moving the eyes, as indicated by the results of my tests with new photographers, and that instantly opened their eyes to seeing the world beyond the single prime object of interest, rapidly progressing into keenly observing the relationships between near and far, left and right, above and below.

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Photographed with Panasonic Lumix G 25mm f/1.7 Aspheric lens on Panasonic DMC-GX8 rangefinder-style camera with tilting electronic viewfinder. The 25mm focal length in Micro Four Thirds is equivalent to 35mm in APS-C and 50mm in the 35mm sensor format aka “full format” or “full frame”.

While the 50mm focal length and its equivalents of 25mm in Micro Four Thirds and 35mm in APS-C have their uses, especially in video and portraiture, I recommend considering focal lengths often described as “perfect normal” such as 40mm in 35mm format, 27mm in APS-C and 20mm in Micro Four Thirds, for the way they better embed their prime subject within a field of background relationships with objects, people and places.

I also recommend reading the analog film and digital sensor normal lens tables in Wikipedia at Normal lens for focal lengths derived from actual film and sensor sizes.

Some “Nifty Forty” lenses for 35mm format sensors

Links

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  • 40mm prime lensesB&H
  • APS-C Lenses, Focal Length: 35mmB&H – includes Fujifilm and Sony E-Mount
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