Who said that 50mm is the equivalent of the human eye?

Postmaster

Postmaster

Dark Side of the Camera
Who said that 50mm is the equivalent of the human eye?

While waiting for the UPS guy to arrive with my FS100, I played with my new Nikons.

Bering bored, I bolted them on my LEX and checking the lenses through the adapter (like an idiot - but what can you do, while waiting on the UPS guy?).

When I had the 50mm on it, I realized that the things I saw where much smaller than what I saw with my bare eye.

It took a 135mm, till the image on the GG and what I saw with my other eye are closely matched. Of course the FOV is much narrower with the lens.

Did I miss something or is that - age old saying " a 50 mil is like the human eye" a misconception?

Frank
 
In full frame still camera 50 mm is 50mm(CANON 5D M2),in the FS100 35MM is equivalent to 50mm because FS100 not a full frame ,fs100 is SUPER35MM motion picture frame size,full frame is 36x20.3 ,super 35mm is 24x14,so in FS100 35mm is a normal lens
thanks
 
Postmaster said:
Who said that 50mm is the equivalent of the human eye?

While waiting for the UPS guy to arrive with my FS100, I played with my new Nikons.

Bering bored, I bolted them on my LEX and checking the lenses through the adapter (like an idiot - but what can you do, while waiting on the UPS guy?).

When I had the 50mm on it, I realized that the things I saw where much smaller than what I saw with my bare eye.

It took a 135mm, till the image on the GG and what I saw with my other eye are closely matched. Of course the FOV is much narrower with the lens.

Did I miss something or is that - age old saying " a 50 mil is like the human eye" a misconception?

Frank
Click to expand...

Agree with you, i never believe that theory anyway, even 50mm on a correct sensor it looks to me tighter than my own field of view, in terms of DOF maybe. But my eyes FOV are mostly reminds me 28mm or 35mm.
 
The focal length of the human eye, AFAIK, averages 16-17mm. The radius or the retina (the equivalent of the sensor diagonal) is 11.5mm, which is a tad bigger than a 2/3" sensor (but is round, so the box that holds it is a bit bigger). The angle of view is therefore equivalent to a 59-61mm lens on a FF sensor (or around 55mm if you use the outer box of the circle).

Watching a monitor is not indicative, as the monitor is in a different location compared you your eye, and you see it from a certain distance that creates a different AOV.

But, the AOV of a single eye is much larger that a 55mm lens, below a 20mm equivalent. How is that possible is a mystery. It may have to do with the fact that your eye is constantly moving, and the actual image you see in your brain is a computation.
 
I don't think 50 mm (On 135 film) really is equivalent to the eye.
The "rule" was the a focal length equal to the frame diagonal was "normal" and roughly equivalent to what the eye sees.
On the 135 frame that is about 43mm, so the 50m is slightly long, I think it came about because that was what Oskar Barnack had available when he put together the Leica 0 prototype, It's also easier to design a good longer lens than shorter.
Dave
 
Frank, this is a great thread... it should be an article in Discover or something... starting with the question and then explaining the biology that gives an answer.

Since our eyes are aspheric and flexible, you know, full of jelly... and all that is under the manipulation of muscles, pressure, etc... I have to wonder if you could assign a focal length to them? Sure, there's a specific point of focus... i.e. my eyes are bad and a specific prescription does allow me to have sharp focus... but the experience of sight is something else. It's bigger... it's an edge to edge FOV where things at the sides are in pseudo-focus. If you tried to draw or somehow recreate all that side-information... you'd have a hard time doing it, because it's there, but it sort of isn't. Stare straight ahead at a point... and you still have a visual information in your periphery.

I think to properly evaluate an apparent focal length for your eyes, you have to first duplicate whatever you're using to judge the comparison... almost like Peter Griffin did when he made a TV frame to suspend in front of himself. If you're using a camera with a 3" LCD across the back, you need to be sure there's no magnification happening between the lens and the LCD... then, if you know you can count on that... grab a piece of cardboard and cut the same 3" rectangle out of that... now put both of those at the same distance from your eye... and see what lens gives you the same FOV through in the "matching" rectangles.
 
Post 2 nailed it

jonatha said:
In full frame still camera 50 mm is 50mm(CANON 5D M2),in the FS100 35MM is equivalent to 50mm because FS100 not a full frame ,fs100 is SUPER35MM motion picture frame size,full frame is 36x20.3 ,super 35mm is 24x14,so in FS100 35mm is a normal lens
thanks
Click to expand...

Edit:
Remember that aps-c cropped sensor is a digital thing. Once upon a time all still cameras and lenses were for full frame film and the phrase "Who said that 50mm is the equivalent of the human eye?" is from still photography
 
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I got distracted for a while cause

MY FS100 ARRIVED!

Yeeeehaw!

Back on topic:

Maybe I did not explain it clear enough.

I was looking - with one eye - trough my Letus 35mm adapter with a 50 mm lens attached at my kitchen lamp.
With the other (naked) eye I was looking at the same lamp.

In common theory, the size of the lamp should be roughly the same.
I´m not talking FOV or DOF - just size = focal length.

But with the naked eye the lamp was much bigger as with the 50mm lens on the 35mm ground glass.
I needed a 135mm lens to get the lamp in the Letus at the same size as I see it with my naked eye.

Of course the FOV was much tighter.

That leads me to the believe that the human eye has a focal length of roughly 135mm but FOV is as wide as a 13mm lens.


Frank
 
the phrase refers to field of view for still photography and it's an old phrase so back then it only referred to full frame.

Put a 50mm lens on an old film still camera or on a 5d m2 and you will see the field of view approximates that of your eye.

Similarly on a cropped digital sensor or an s35 size digital sensor the equiv lens For that feild of view would be a 35mm focal length
 
So it´s just FOV not focal length right?

......





did I mention that my

MY FS100 ARRIVED!

..just saying :beer:
 
What this is referring to is the "non distorted" image.

in Motion picture, the "normal lens" is a 32-40mm. It is neutral, neither wide nor telephoto. This length reflects what in our eyes is the foveon structure. The patch of rods and cones that make up our "active" vision segment of what we perceive. The border of where our vision goes peripheral is a similar frame to 50mm on Still, and 32mm on Motion picture roughly. I have a theory that this is why certain lens manufacturers, like cooke for example, make a 32mm instead of a 35mm lens. Its only 7mm jump from their 25mm lens, and then the next lens up is the 50mm. 7mm from 25mm? then a full 18mm jump up? but you know what, the 32mm just looks amazing. So lets do some math, 32mm x1.6 crop = 51.2mm; very very close to 50mm equivalent in full frame.
 
Fov and focal length are a directly connected ratio if the sensor size is a constant.

Hey did your fs100 arrive yet? :)
 
That's funny, I checked once in the D90 days and around 55mm my eye saw things as big as was in the vf.

I checked also by magnification. ie things being the same size both eyes open, one on vf one naked.
 
greymog said:
That's funny, I checked once in the D90 days and around 55mm my eye saw things as big as was in the vf.

I checked also by magnification. ie things being the same size both eyes open, one on vf one naked.
Click to expand...


someone didn't read my posts! :) the d90 is not full frame, its approx the same as s35 or aps-c.
you want a nikon FX camera like d3, d3x, d3s or d700
 
Interesting thread. I was trying to explain the 50mm thing to my fiance and didn't realize that the saying applied to old school film cameras.
Now I gotta try and explain it all over again...
*I wonder if the guy got his FS100...?*
 
TimurCivan said:
What this is referring to is the "non distorted" image.

in Motion picture, the "normal lens" is a 32-40mm. It is neutral, neither wide nor telephoto. This length reflects what in our eyes is the foveon structure. The patch of rods and cones that make up our "active" vision segment of what we perceive. The border of where our vision goes peripheral is a similar frame to 50mm on Still, and 32mm on Motion picture roughly. I have a theory that this is why certain lens manufacturers, like cooke for example, make a 32mm instead of a 35mm lens. Its only 7mm jump from their 25mm lens, and then the next lens up is the 50mm. 7mm from 25mm? then a full 18mm jump up? but you know what, the 32mm just looks amazing. So lets do some math, 32mm x1.6 crop = 51.2mm; very very close to 50mm equivalent in full frame.
Click to expand...

i think the reason you don't get the 40 and 65:

if it's a 5,6 lens set or package it can't cover the whole range
if you split it up for framing, 24/25,32 and 50,75/85-ish it's about the same difference (7 or 8mm at the wide-ish end is similar to 25mm at the telephoto-ish end), that's 4 lens already and you have to choose either go super wide or telephoto for the last 1,2 lens or split 2 lens and get
18
24,32
50,75/85
100/135

but it does cause a gap in the fov, a lot of people like the 40/42mm more than 50mm for interior shots.
 
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J Davis said:
someone didn't read my posts! :) the d90 is not full frame, its approx the same as s35 or aps-c.
you want a nikon FX camera like d3, d3x, d3s or d700
Click to expand...

Read that man sorry I passed for missing it, but I didn't consider that, I was looking at magnification. Isn't a 50 a 50 regardless of how much the sensor 'crops' out? I was holding the thing up to my eye, wasn't really seeing how far wide I could catch from end to end, just how big my subject was in the vf in comparison to what my other eye saw.

This sensor talk is confusing. :)
 
As I understand it, for any format the "normal" lens is the focal length roughly equal to the image circle diameter of that format.

But I understand what Frank is saying. "Normal" as far as magnification and perspective matching our vision, forget FOV, is pretty much unique to each of us. I am quite near sighted and for me focal lengths around 80mm produce equal magnification and perspective to what I see with corrected vision and this seems to be true regardless of format. It is the same for my 1/3" DV camcorder as it is for my FF35 and medium format still cameras.
Frank found his match at 135mm.
 
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