Human Eye Focal Length

[boojum]

Most of us have two eyes with overlapping fields of view, and peripheral vision.
And my eyes don't take still photos; do yours?

Chris

Only if I close one eye and blink. ;o)

I am not sure we are trying to reproduce normal vision but to give a good version of it. Cinerama fooled us, those who saw it and can remember it, by reproducing the wide field of vision. It was amazing. But it also took three cameras. So we can make a compromise at best. As I just posted I understand the ~43mm on a 35 to reproduce what the eye sees even if not in its entirety but as a subset of the entire field of view.

With an effective 43 or with an actual 40 I get pretty much what I see in the eye which is not on the viewfinder. Through the M240 EVF the image is small but has the right field of view. I do not get binocular vision but I do know I see the same thing with both eyes

 

[TenEleven]

There seems to be what is approaching consensus that ~43mm on a 35mm camera yields very close to what we see. But it does not yield all of what we see. So I am going to make a leap here and suggest that if we could get a panoramic view with this 43mm lens we could recreate what we see. However what we do get is the perspective in a subset of the entire view. Does this make sense to the rest of you?

Please say "yes" as I am sitting here thinking I am pretty damned smart and would hate to have the illusion disturbed. ;o)

Again this is based on the (very simplified) premise that we see like a camera sees, which - as others have already abundantly highlighted - we do not. If I had to compare the way our vision works to a machine then perhaps a scanner (flatbed or film) would come to mind. We scan a scene with our pupils and in the process a composite is formed in our mind. What we focus on gets the most attention and thus resolving power. In recent years we have even learned that not everything we see is actually fully congruent with "factual reality", as our brain applies substitutions and shortcuts in order to expedite this very response-time sensitive process. (If you ever reached for the milk in your fridge only to find there was no milk you have experienced this yourself.)

You don't need to see every detail of the tiger in the bush, but certain patterns of color and motion will trigger your visual cortex to "say" tiger and then put one there because every millisecond counts.

Then what constitutes for you as the "valid" field of view? Is it what we see in front of us? The part we see the clearest, which is resolved on the fovea centralis? (Covering a mere 1° to 2° - or in 35mm camera terms a 1000mm lens!) Monocular or binocular vision? Your entire peripheral vision? Just the part we see in color? (Which, mind you does not even include color vision - the color we see in our periphery is a based on a sort of best-effort basis - a guess made by your mind. You can test this by having a friend slowly move colored pencils into your peripheral view as you look ahead. Go ahead and try to guess the color!)

Basically you have to get reductive to a point where I do not think there is much value in attaching a focal length number to your vision (Again what part of it?). And even if you do, then that number may be valid for you and for you at this certain point in time and age, since everyone is going to see the world slightly differently and our vision undergoes changes as we grow and age...

 

[boojum]

Again this is based on the (very simplified) premise that we see like a camera sees, which - as others have already abundantly highlighted - we do not. If I had to compare the way our vision works to a machine then perhaps a scanner (flatbed or film) would come to mind. We scan a scene with our pupils and in the process a composite is formed in our mind. What we focus on gets the most attention and thus resolving power. In recent years we have even learned that not everything we see is actually fully congruent with "factual reality", as our brain applies substitutions and shortcuts in order to expedite this very response-time sensitive process. (If you ever reached for the milk in your fridge only to find there was no milk you have experienced this yourself.)

You don't need to see every detail of the tiger in the bush, but certain patterns of color and motion will trigger your visual cortex to "say" tiger and then put one there because every millisecond counts.

Then what constitutes for you as the "valid" field of view? Is it what we see in front of us? The part we see the clearest, which is resolved on the fovea centralis? (Covering a mere 1° to 2° - or in 35mm camera terms a 1000mm lens!) Monocular or binocular vision? Your entire peripheral vision? Just the part we see in color? (Which, mind you does not even include color vision - the color we see in our periphery is a based on a sort of best-effort basis - a guess made by your mind. You can test this by having a friend slowly move colored pencils into your peripheral view as you look ahead. Go ahead and try to guess the color!)

Basically you have to get reductive to a point where I do not think there is much value in attaching a focal length number to your vision (Again what part of it?). And even if you do, then that number may be valid for you and for you at this certain point in time and age, since everyone is going to see the world slightly differently and our vision undergoes changes as we grow and age...

What you have written may all be true. Strangely it calls to mind the argument between Boswell and Johnson about the rock. The two were out for a walk and there was a rock in their path. Boswell opined that Johnson could not make a philosophical proof of the rock's existence. Johnson kicked the rock and said, "It is there."

There may be a lot of apparent academic argument about this but I am just interested in what I seem to see. With the one camera it is almost exactly binocular vision. That works for me whether I understand the scientific underpinnings or not. Sort of like the old adage of asking what time it is and being told how to build a watch.

Your position is very interesting but way above my pay grade. I am only speaking for myself.

 

[Mos6502]

Hold on a minute. Not an odd choice at all. It was the standard choice. The standard lens for the Tenax II is 40mm. It gives the same perspective as the 50mm lens does for 24x36. But also note the "normal" lenses for the Olympus Pen series which started at 38mm and went up to 42mm—way narrower than the equivalent in 24x36.

The standard lens for the Pen was 28mm, not 38mm (I'm not sure where the 38mm figure comes from, I've never seen it). As well, almost every half frame camera from every other manufacturer came with a lens shorter than 38mm. Just for example: Fujica Mini 25mm, Fujica Half 1.9 33mm, Petri Half 25mm, Ricoh Auto Half 25mm, Yashica Half 17 32mm. So I'm not sure what the basis is for the claim that 38mm and 42mm would have been considered "standard" for the half frame format.

Tenax cameras are also hardly typical, if anything, I think most of us would consider the Tenax an unusual camera.

 

[TenEleven]

The standard lens for the Pen was 28mm, not 38mm (I'm not sure where the 38mm figure comes from, I've never seen it). As well, almost every half frame camera from every other manufacturer came with a lens shorter than 38mm. Just for example: Fujica Mini 25mm, Fujica Half 1.9 33mm, Petri Half 25mm, Ricoh Auto Half 25mm, Yashica Half 17 32mm. So I'm not sure what the basis is for the claim that 38mm and 42mm would have been considered "standard" for the half frame format.

Tenax cameras are also hardly typical, if anything, I think most of us would consider the Tenax an unusual camera.

Wes is talking about the Tenax which is a square camera. Other such square examples (many which came per default with a 40mm lens!) are the Taxona, the Mamiya Sketch (35mm lens), The Robot series (Original, Star, Royal 24).. After which he talks about the olympus pen he very clearly means the Pen F Single lens reflex system, and that indeed did come with a 38mm lens as the standard option and the faster 42mm as a premium option.

First of all the Petri Half is 28mm not 25mm. Also, neither The Ricoh Auto Half nor the Fujica mini, which I also possess and have shot extensively possess the ability to focus. These are fixed focus cameras. The wide angle is a very obvious choice here to maximize the apparent depth of field in order to avoid customers being unhappy with unsharp pictures. The same rationale follows for some half-cameras, especially those without a focus aid (scale focus) opting for wider focal lengths. Or with very rudimentary (3 step) autofocus system such as the Konica Recorder (24mm).

Lastly the Yashica Half 17 at 32mm is pretty much a 50mm view with 32x1.44 = 46mm. 32mm, 30mm or even 35mm is also a very common focal length on Canon (Demi EE17) Olympus (Pen, Pen D, Pen EED, Pen D3, etc etc.) half frame cameras as well, especially the faster lensed models.

What exactly do you think the "W" in the 25mm lensed Onlympus Pen-W denotes? It's a wide angle (aka not normal view) camera

 

[TenEleven]

I don't know what you are trying to achieve here by arguing against the historical fact that 50mm was the de-facto standard for several decades to the point that these lenses are ... drum roll.. called "standard lenses" for that very reason. Crack open any 40ies all the way to the 2000s Popular Photography or other such photo magazine in any laguage and you will find 50mm lenses referred to by that term.

This is true in other languages such as English, Japanese ("標準レンズ"), French ("objectif standard") and German ("Standardobjektiv") as well by the way. Heck there's even a Wikipedia article about it.

 

[Mos6502]

This has already been addressed directly. There shouldn't be any confusion on the matter.

The vast majority, and I do really mean the vast majority of cameras, of all types, all formats, ever manufactured, use lenses with a wider angle of view than that given by a 50mm lens on 135. This is indisputable.

If you want to muddy the waters with semantics, there is a difference in definition between "normal" and "standard". Of course that discussion is beside the point.

 

[Mos6502]

Just for fun, anybody here can look up the most produced 35mm camera in history, and report back here with the focal length used on that camera. 🙂

 

[boojum]

Just for fun, anybody here can look up the most produced 35mm camera in history, and report back here with the focal length used on that camera. 🙂

The two most-produced 35mm cameras of all time? You've probably never heard of them

What were the most-produced 35mm cameras of all time, you ask? Perhaps the Argus C3, the Olympus Trip 35, or maybe the Nikon F? Not even close!

www.dpreview.com

 

[pgk]

Most of us have two eyes with overlapping fields of view, and peripheral vision.

And what we 'see' is actually a processed image which is de-distorted and heavily interploated.

As has been said, a simply experiment serves to illustrate how our actual optical vision is actually very different from what we think we see. Get a friend to stand behind you with a brighly coloured object but one which you don't know the colour of. As it is brought slowly into your field of vision try to work out what colour it is. Eventually it will move into the central, colour sensitive part of the eye and its colour will be revealed but up until that point it will not be possible to tell what colour it actually is. However, the exception is if you recognise the object andif it is of a 'known' colour, then it will appear to be coloured far sooner. This is true for most things we look at. The brain adds information based on its understanding of what is being seen. So here in the UK we may see a post box peripherally and the brain will recognise it and fill in the colour as they are always bright red.

Also, we have an extremely wide field of view based on not purely optical cosiderations but also on eye motion and experience. We must see straight lines optically as curved but our brain knows that they are not and we don't 'see' them as curves.

So the eye/brain system is complicated and has a large dose of image manipulation thrown in as standard. The 'raw' files sent from our eyes are probably very different from our perception.

Which is why I don't think that the optics of our eyes have anything to do with our favoured photographic focal lengths.

 

[raydm6]

I never equate my vision to what the camera sees; rather, I visualize - in my mind - what will be framed in the camera/lens/viewfinder: i.e, what the camera sees.

In the martial-arts, we use "soft-eye" gaze to take in more (especially peripherally). You need to see both the hands and feet of the aggressor while also being aware peripherally (we train through kata and bunkai - multi-attack scenarios from many directions and angles).

Peripheral vision is expanded a bit when you take your straight-ahead soft gaze, and lower your gaze to a point about 4-feet in front of you. You will notice you see a bit more to your your sides): your shoulders come more into view and perhaps you can perceive a bit more behind you. Good thing to know on the street when out and about and confronted with an aggressive situation.

Miyamoto Musashi and Vision In Martial Arts

Seeing is believing but can training help refine what we actually perceive?

www.psychologytoday.com

 

[JohnGellings]

There seems to be what is approaching consensus that ~43mm on a 35mm camera yields very close to what we see. But it does not yield all of what we see. So I am going to make a leap here and suggest that if we could get a panoramic view with this 43mm lens we could recreate what we see. However what we do get is the perspective in a subset of the entire view. Does this make sense to the rest of you?

Please say "yes" as I am sitting here thinking I am pretty damned smart and would hate to have the illusion disturbed. ;o)

I think we are overthinking something that doesn't matter. Our eyes do not see like a camera lens with a framing device cropping it.