Architect1776 Loc: In my mind

Why is 50mm generally considered the transition point between what is considered wide angle and telephoto?
It seems that this would vary depending upon format and even to a greater extent the subjective opinion of someone.

ken_stern Loc: Yorba Linda, Ca

Here is my quick take --
Though the real pros in this forum will provide a more exact optical if not scientific explanation --
All of this is based on the 35mm format

The 50mm is generally considered the angle of view of human eyesight when the eye is at rest --
Even though it is not quite
So every angle of view below 50mm can be considered a wider angle of view while all above 50mm can be
& is considered telephoto

bsprague Loc: Lacey, WA, USA

Deleted. Ken_stern beat me to it.

Architect1776 Loc: In my mind

Is that truly the angle of view of human eyesight?
I believe not from personal experience.
So again why was that chosen? 35mm is much more recent than many other formats.

bsprague Loc: Lacey, WA, USA

I think it is a best guess going back to the introduction of 35mm SLR cameras where the camera makers needed a suggestion for the "kit lens".

Our peripheral vision, where we can detect motion, is nearly 180 degrees where the 50mm lens is about 40 degrees.

zug55 Loc: Naivasha, Kenya, and Austin, Texas

Two issues are conflated here: focal length and field of view.

The focal length refers to the optical qualities of a lens. This does not vary, regardless what sensor format you use. While definitions wary, I would consider anything wider than 35mm a wide-angle lens.

Field of view refers to how wide the angle is that your lens in combination with your sensor cover. A 40mm full-frame lens is thought to produce a field of view that roughly corresponds to the experience of the human eye--some think that this is closer to 50mm. However, if you use and APS-C system, you would achieve the same angle of view by using a 27mm lens.

So there isn't a straight answer to the question because the same lens strapped on a camera with a different sensor size will give you a different field of view.

But I suspect that OP already knew that. So many posts here are just click bait--the game is to generate the largest possible number of responses to a fairly silly question.

PHRubin Loc: Nashville TN USA

The standard is for a 50 mm (35mm equivalent), so the sensor size does matter. Actually, I believe, in reality, ~40-45mm is closer.

Ysarex Loc: St. Louis

No. The angle of view of human eyesight is more complicated.

Every format has it's "normal" lens focal length. There's a basic rule of thumb and it's applied with a good dash of convention thrown in; the normal lens for any film/sensor format is roughly the diagonal of the format rectangle (or square). So for 35mm (FF) film the diagonal is 43m. The dash of convention rounded that up to 50mm and most 35mm cameras came with 50mm normal lenses. There have always been outliers and so an occasional camera would be given a 40mm or a 45mm or a 55mm or even a 58mm as a normal lens.

With a normal lens on the camera the view through the camera is approx. the same magnification as you see with the unaided eye. Pentax took that the full distance with their 6x7 medium format film camera and delivered the camera with a 105mm normal lens and a viewfinder that would allow the user to look through the camera with one eye while keeping the other eye open and both eyes seeing the subject at the same magnification. Put a lens on the camera wider than normal and the subject appears smaller while with a lens longer than normal the subject appears larger.

Architect1776 Loc: In my mind

There was NO mention of field of view, only focal length.

Architect1776 Loc: In my mind

I never once mentioned "Normal" I said 50mm.

delder Loc: Maryland

In the [35 mm] Film Days, the 50mm fixed lens was often what was kit to your SLR. We would then acquire a wide angle &/or telephoto lens or 2 according to our BUDGET & needs.
ZOOM lenses were a luxury back then, & slower. With limited choices in Film ASA/ISO @ the time, this was more of a problem than today.

Ysarex Loc: St. Louis

50mm is most commonly considered the normal lens for 35mm(FF) cameras. You noted that it's position between wide and telephoto should vary by format. It does. On a 6x9 film camera 50mm is considered a super wide angle and not the middle point between wide/tele.

BebuLamar

I think it's close. You feel that you can see a much wider angle because your eye ball turns.

Architect1776 Loc: In my mind

Actually NOT.
Look it up.

Jersey guy Loc: New Joisey

My old Beseler Topcon (1958) had a 58mm lens. I think that somewhat longer focal length was imposed in that early SLR world because of the need to clear the mirroays what so eor when ti flipped. Later, I had a Konica FS with a 40mm as "normal". But my understanding was always that the accepted convention was that normal was the diagonal measurement of the format being discussed.