Closest lens to human eye experiment

[Disastrous]

You know that old discussion about which lens is closest to the human eye, and how everyone says 50mm on a FF is the one?

Well, try this:

I just fitted my 18-200 zoom and then put my usual right eye to the viewfinder but kept my left eye open. Then I zoomed until with both eyes open I could see a clear image, as if instead of looking down a lens, I just had a frame round one eye.

The focal length on the barrel? 50mm. But on my 60D, so by my reckoning a real life 80mm.


So is 80mm really closest to human eye field of view? Is my experimental logic sound, even??

Anyway, I'm clearly not busy enough this afternoon but was curious to see if others had tried this?

[Glosphil]

You have just proved that a 50mm lens is closest to the human eye view.

Clue? - 60D's 1.6x "focal length crop". 80/1.6 = 50 .

[MysteryLemon]

No its the other way round, 50mm equivalent on a canon crop body would be more like 31mm indicated on a zoom lens designed for that system.

If the OP has his lens set to 50mm, then he is indeed looking at an 80mm full frame equivalent through the viewfinder. If he set his lens to 31mm, he would be seeing roughly a 50mm full frame equivalent.

Would viewfinder magnification and crop not come into play as well here?

Edited by MysteryLemon on Tuesday 29th September 16:39

[fido]

MysteryLemon said:

Would viewfinder magnification and crop not come into play as well here?

Yep, I was thinking the same - you have to compare what is in the framed image (or liveview) with what you eyes sees - though your eye can move around so the human field-of-view seems larger. I thought the general consensus was 50mm (for 35mm FF), or 35mm if you include the periphery.

[Disastrous]

Glosphil said:

You have just proved that a 50mm lens is closest to the human eye view.

Clue? - 60D's 1.6x "focal length crop". 80/1.6 = 50 .

Wrong - it's as MysteryLemon puts it.

My lens is set to 50mm on a crop body. So you multiply by 1.6 to get the FF equivalent. Hence 80mm.


I'm not sure about viewfinder magnification and so on - what's the story there? I thought the whole point of SLRs was that you see what the camera sees?

[PorscheGT4]

One eye without moving can see greater than 16mm field of view, I have no wider lens to get the correct figure.

So depends what you are asking, but you did say field of view, if that's the case your eyes are broken if your field of view is only 80mm.

[Disastrous]

PorscheGT4 said:

One eye without moving can see greater than 16mm field of view, I have no wider lens to get the correct figure.

So depends what you are asking, but you did say field of view, if that's the case your eyes are broken if your field of view is only 80mm.

I'm not really sure what I'm asking but I suppose it is 'what lens is closest to what we see?'

My thinking was working through the zoom with both eyes open, will lead to a point of magnification where the right eye through the viewfinder's image overlaps with the left's perfectly, meaning that say horizontal lines etc continue across your field of view uninterrupted.

Would this not equate to 'closest to human eye'?

[ExPat2B]

I find that with an 85mm lens on full frame I get the same magnification and perspective that my other eye gets.

I think that's why 85mm is so good for portraits, just seems to get the face right at normal viewing distance.

[Disastrous]

ExPat2B said:

I find that with an 85mm lens on full frame I get the same magnification and perspective that my other eye gets.

I think that's why 85mm is so good for portraits, just seems to get the face right at normal viewing distance.

That would concur with my courageous and scientific 'research' this afternoon

[Mr Will]

Disastrous said:

PorscheGT4 said:

One eye without moving can see greater than 16mm field of view, I have no wider lens to get the correct figure.

So depends what you are asking, but you did say field of view, if that's the case your eyes are broken if your field of view is only 80mm.

I'm not really sure what I'm asking but I suppose it is 'what lens is closest to what we see?'

My thinking was working through the zoom with both eyes open, will lead to a point of magnification where the right eye through the viewfinder's image overlaps with the left's perfectly, meaning that say horizontal lines etc continue across your field of view uninterrupted.

Would this not equate to 'closest to human eye'?

What do you think would happen if you put your lens on a camera with a larger or smaller viewfinder? You'd need a different focal length to achieve 1:1 magnification, even if the sensor size was exactly the same. You'd end up with .different images as a result.

1:1 viewfinder magnification is pretty easy to narrow down though - it's just a mathematical formula - but closest to the human eye is a much more difficult question. Our eyes don't work like a camera. We have an extremely wide angle of view, but only high resolution over a part of that. There are blind spots directly in front of us and only parts of our vision are in colour. You don't notice any of this because your brain is constantly "cheating" and filling in the information based on what it has scanned with your eyes previously.

There's a good article on the differences here: http://www.cambridgeincolour.com/tutorials/cameras...

[Disastrous]

Mr Will said:

Disastrous said:

PorscheGT4 said:

One eye without moving can see greater than 16mm field of view, I have no wider lens to get the correct figure.

So depends what you are asking, but you did say field of view, if that's the case your eyes are broken if your field of view is only 80mm.

I'm not really sure what I'm asking but I suppose it is 'what lens is closest to what we see?'

My thinking was working through the zoom with both eyes open, will lead to a point of magnification where the right eye through the viewfinder's image overlaps with the left's perfectly, meaning that say horizontal lines etc continue across your field of view uninterrupted.

Would this not equate to 'closest to human eye'?

What do you think would happen if you put your lens on a camera with a larger or smaller viewfinder? You'd need a different focal length to achieve 1:1 magnification, even if the sensor size was exactly the same. You'd end up with .different images as a result.

1:1 viewfinder magnification is pretty easy to narrow down though - it's just a mathematical formula - but closest to the human eye is a much more difficult question. Our eyes don't work like a camera. We have an extremely wide angle of view, but only high resolution over a part of that. There are blind spots directly in front of us and only parts of our vision are in colour. You don't notice any of this because your brain is constantly "cheating" and filling in the information based on what it has scanned with your eyes previously.

There's a good article on the differences here: http://www.cambridgeincolour.com/tutorials/cameras...

Intersting article - thanks.

I see what you mean about the viewfinder but I'd always assumed that due to them showing the 'whole frame' (or close to) then somehow any physical size difference wouldn't matter.

You reckon then, that on a different viewfinder, I might find an entirely different focal length provides the same effect?

I also take the article's point about our much wider FOV with more detail in the middle and how a 50mm seems a good tradeoff between view and distortion. Interesting.

[Mr Will]

Disastrous said:

I see what you mean about the viewfinder but I'd always assumed that due to them showing the 'whole frame' (or close to) then somehow any physical size difference wouldn't matter.

You reckon then, that on a different viewfinder, I might find an entirely different focal length provides the same effect?

Yes - your viewfinder will have a level of magnification as well as your lens: https://luminous-landscape.com/understanding-viewf...