# naked eye equivalent?



## Rocguy (Mar 23, 2013)

I can't seem to find the answer to my question, which is what lens could I buy for my T4i (or any crop camera) that would give me an equivalent to what the naked eye sees? 24mm? 35mm? Sorry if this has been asked a million times but I'm just curious. I recently got a 50mm, 1.8, and am loving it. I wish my camera had come with this lens! But it has gotten me curious about other prime lenses and I want one that's close to the naked eye. 

Thanks for any help or info. 

P.S. Is the 50mm the naked eye equivalent for a FF camera?


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## Jim Saunders (Mar 23, 2013)

You might well hear different but as far as I know 50mm is pretty close to normal human vision.

50mm focal length is 50mm focal length as long as the lens matches the mount on your camera; Your EF 50mm f/1.8 on a Rebel will look like about 80mm because the Rebel has a smaller sensor. If you have an 18-55 you could set it to 50mm and compare it to the results from your 50mm f/1.4.

Jim


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## Sporgon (Mar 23, 2013)

It's generally considered that a 50mm on FF gives the same prospective as our vision, ie the magnification of the scene from a given distance, but the 35mm is closer to our conscious field of view. However some suggest that when we concentrate on an object close to us our prospective in lens terms becomes more like 85mm. 

In APS-c these become 32mm, 22mm and 54mm. They translate directly because they provide the same field of view as FF and as prospective is a result of distance it is the same with these lenses.

But it becomes more complicated as people often don't realise that we do not 'see' with our eyes, it is our brain which 'sees', our eyes are just like the lens on the camera. This is why a camera will never be able to really match what we can see in one exposure; we are seeing the world in what is in photographic terms a combination of HDR and focal length and focus stacking !


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## RS2021 (Mar 23, 2013)

As standards go, one can arbitrarily subscribe to either a" wide" or "normal" standard...very lose terms that are filled by the 35mm and 50mm respectively in the full frame world. The "real" normal would actually be a ~42mm for which there was no prime in the Canon full frame lens pantheon....until they released the EF 40mm pancake.

But you are lucky as in the crop field you actually have several primes that will fit all three slots....just pick one.

24mm is a ~38mm field of view (FOV) on crop (24LII, 24 f/2.8 discontinued, 24 f2.8 IS and the 24 TSE)
28mm is ~45mm FOV on crop (28 f/1.8, 28 f/2.8, 28 IS)
35mm is a ~56mm FOV on crop (35L, 35 f/2, 35 f/2 IS)

Cheers!


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## rs (Mar 23, 2013)

Jim Saunders said:


> 50mm focal length is 50mm focal length as long as the lens matches the mount on your camera; Your EF 50mm f/1.8 on a Rebel will look like about 80mm because the Rebel has a smaller sensor. If you have an 18-55 you could set it to 50mm and compare it to the results from your 50mm f/1.4.


To get the FoV that a 50mm gives on FF, use an EF-S 18-55 at 31mm. An 18-55 @50 gives an identical FoV as a 50/1.4 if they're both on a crop body.

In terms of primes, somewhere in the region of 28-35mm is close to that 31mm to give equivalent FoV of a 50mm on FF.

However, the human field of view is said to be nearer to a lens with a focal lens equal to the diagonal of the sensor - 50mm lenses are cheap and easy to manufacture, and very close to this length, hence their popularity - but 43mm on FF is the nearest match to the human eye. Which makes something close to 27mm lens on crop ideal.


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## c.d.embrey (Mar 23, 2013)

For Full Frame it's 43.3mm. AFAIK Pentax is the only camera company to make a 43mm lens. For a Canon APS-C it's 27.3mm and 28.4mm for a Nikon DX.

*"For still photography, a lens with a focal length about equal to the diagonal size of the film or sensor format is considered to be a normal lens."* http://en.wikipedia.org/wiki/Normal_lens


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## Pi (Mar 23, 2013)

The human eye(s) do not see uniformly. We can see almost like a fisheye lens http://en.wikipedia.org/wiki/Human_eye#Field_of_view. The quality of the periphery though is extremely poor by photography standards. It quickly degrades from the center, actually. We see by scanning the scene.

The "standard" AOV/FL is usually accepted to be somewhere between 40mm and 50mm on FF but there cannot be exact definition (despite what wikipedia claims). If you want to replicate a portion of what you see, you need to measure the width of the picture on your monitor at a typical viewing distance, and the distance to it. If that picture is, say 36cm wide, and you view it from 45cm, then you need a 45mm equivalent lens. Not that any other lens will produce poor images.


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## c.d.embrey (Mar 24, 2013)

Pi said:


> The "standard" AOV/FL is usually accepted to be somewhere between 40mm and 50mm on FF but there cannot be exact definition (despite what wikipedia claims).



The frame diagonal is the standard used by photographers since the beginning of time. I learned this rule way back in the 1960s, well before anyone thought of starting Wikipedia. People were using a 150mm as a standard lens for 4x5 well before Oskar Barnack inverted the 24x36mm still film camera.


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## Pi (Mar 24, 2013)

c.d.embrey said:


> The frame diagonal is the standard used by photographers since the beginning of time. I learned this rule way back in the 1960s, well before anyone thought of starting Wikipedia. People were using a 150mm as a standard lens for 4x5 well before Oskar Barnack inverted the 24x36mm still film camera.



And what is the rational behind this "rule"?

BTW, 150mm on 4x5 is about 8.4% below the "standard" 163mm; like 39.9mm on FF.


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## risc32 (Mar 24, 2013)

honestly, i've never really understood this. my vision is nothing like a 50, 43, or 35mm lens. more like a fish eye, that i scan around in with a varying area of focus. i'm sure what i'm not actually focusing on is a complete mess but my brain is pretty damn good at filling in the pieces, and getting right what it needs to get right. now that i think about it, it could be a method to ease the brain's workload to fight off fatigue. like the way a racer/ fighter jet pilot let's go of everything they see around them that they don't need.


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## c.d.embrey (Mar 24, 2013)

Pi said:


> And what is the rational behind this "rule"?



There are lots of concepts, like this and the Golden Rectangle (Google it) in the art world. They have been around for hundreds of years and you are ain't gonna change it. Have a nice day.


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## Barrfly (Mar 24, 2013)

you might be pleased with the 40mm pancake on a cropped camera, for the price ( under $200.00 ) it's quite nice.


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## TrumpetPower! (Mar 24, 2013)

First, as others have noted, the human visual system has a field of view approaching 180°, but acuity is limited to a very small central region. There's actually an excellent XKCD devoted to the subject.

The photographic definition of a "normal" focal length being equal to the diagonal of the sensor / film format has much more to do with perspective than anything else. It just so happens that a comfortable viewing distance varies with image size, such that you tend to preserve the same angle of view regardless of print size. That is, you'll stick your nose in a 4" x 6" print, you'll look at an 8" x 10" print from normal reading distance, you'll stand back to look at a 24" x 36" print, and you'll look at that billboard from a block away.

And, at that typical viewing distance, the perspective of a normal focal length lens is such that it pretty much matches the same perspective the photographer saw. That is, if you're using a normal lens, if you make an instant 8" x 10" print right there and hold it in front of you at reading distance, the print is going to match up very closely with the original scene.

You know how wide-angle lenses tend to give a distorted perspective? Well, stick your nose in the print, and it suddenly doesn't look so distorted. Same thing with telephoto lenses and their compression; stand back a ways, and it looks quite normal.

So...short version, is, there is no camera that duplicates human vision. Cameras and eyes are two radically different imaging systems. Each can do things the other can't.

I _would,_ however, encourage you to spend a lot of time experimenting with the matter. Pick some sort of still life and get really friendly with it. Shoot it from all different positions with all different lenses -- anything and everything you can get your hands on, even if only by borrowing and / or renting. Shoot at different apertures, while you're at it. And, most importantly -- though you might not realize it right now -- play with the light. Just a couple cheap task or work lights, a bulb with a reflector, will do -- and extra bonus points if you can dim them. Move the lights all around the scene as you move around the scene.

The purpose of this exercise, of course, isn't to create great art. Rather, it's to get a visceral, hands-on understanding of what the relationship is between perspective and position and focal length and how light plays together and all that stuff. Don't worry...once you see some of these things, you'll have more than one "ah-HA!" moment, and that'll inspire you to go do something truly creative.

Cheers,

b&

P.S. Your homework assignment: find out the actual dimensions of your camera's sensor, including the diagonal. It's in the manual and on the manufacturer's Web site, along with other places. Then, cut a hole in a piece of paper the same size as said sensor. Now, hold that paper up to your eye. Have a ruler handy so you can see how far the cutout is from your eye, and compare with the numbers on your camera's lens. b&


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## Pi (Mar 24, 2013)

c.d.embrey said:


> Pi said:
> 
> 
> > And what is the rational behind this "rule"?
> ...



So you cannot answer my question. Weird, no major manufacturer seems to take that "rule" seriously.


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## serendipidy (Mar 24, 2013)

From Wikipedia (the standard for all knowledge ) on the human eye:

Field of view

The approximate field of view of an individual human eye is 95° away from the nose, 75° downward, 60° toward the nose, and 60° upward, allowing humans to have an almost 180-degree forward-facing horizontal field of view.[citation needed] With eyeball rotation of about 90° (head rotation excluded, peripheral vision included), horizontal field of view is as high as 270°. About 12–15° temporal and 1.5° below the horizontal is the optic nerve or blind spot which is roughly 7.5° high and 5.5° wide.[6]

In photography and cinematography a normal lens is a lens that reproduces a field of view that generally looks "natural" to a human observer under normal viewing conditions, as compared with lenses with longer or shorter focal lengths which produce an expanded or contracted field of view that distorts the perspective when viewed from a normal viewing distance.[1][2] Lenses of shorter focal length are called wide-angle lenses, while longer-focal-length lenses are referred to as long-focus lenses[3] (with the most common of that type being the telephoto lenses).

For still photography, a lens with a focal length about equal to the diagonal size of the film or sensor format is considered to be a normal lens; its angle of view is similar to the angle subtended by a large-enough print viewed at a typical viewing distance equal to the print diagonal;

[edit]


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## serendipidy (Mar 24, 2013)

The answer is *42 * ;D


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## TrumpetPower! (Mar 24, 2013)

serendipidy said:


> The answer is *42 * ;D



You jest, of course...but the answer on 135 format ("full frame") is actually pretty close to that: about 43 1/4.

Now, if only somebody could tell me a decent place to have dinner that isn't at the End of the Universe....

Cheers,

b&


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## rpt (Mar 24, 2013)

serendipidy said:


> The answer is *42 * ;D


ROFL! ;D


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## rpt (Mar 24, 2013)

TrumpetPower! said:


> serendipidy said:
> 
> 
> > The answer is *42 * ;D
> ...


Forty second street


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## Zlatko (Mar 24, 2013)

RS2021 said:


> As standards go, one can arbitrarily subscribe to either a" wide" or "normal" standard...very lose terms that are filled by the 35mm and 50mm respectively in the full frame world. The "real" normal would actually be a ~42mm for which there was no prime in the Canon full frame lens pantheon....until they released the EF 40mm pancake.
> 
> But you are lucky as in the crop field you actually have several primes that will fit all three slots....just pick one.
> 
> ...



Of those, I think the 28mm would be the closest to a "true normal" on a 1.6x crop body, very close to what a 43mm would be on full frame. I have often used a 28mm on a crop body and it feels like a "normal" lens on that body.


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## Rocguy (Mar 24, 2013)

TrumpetPower! said:


> I _would,_ however, encourage you to spend a lot of time experimenting with the matter. Pick some sort of still life and get really friendly with it. Shoot it from all different positions with all different lenses -- anything and everything you can get your hands on, even if only by borrowing and / or renting. Shoot at different apertures, while you're at it. And, most importantly -- though you might not realize it right now -- play with the light. Just a couple cheap task or work lights, a bulb with a reflector, will do -- and extra bonus points if you can dim them. Move the lights all around the scene as you move around the scene.
> 
> The purpose of this exercise, of course, isn't to create great art. Rather, it's to get a visceral, hands-on understanding of what the relationship is between perspective and position and focal length and how light plays together and all that stuff. Don't worry...once you see some of these things, you'll have more than one "ah-HA!" moment, and that'll inspire you to go do something truly creative.
> 
> ...



I appreciate this suggestion very much. I'm right at the point in my learning where I get frustrated because I'm realizing how important the lighting is in my trying to capture what I want. But I haven't played around with it enough to know when/where/how to adjust lighting to get what I want/better photographs. 

And I will do the homework assignment!


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## Dick (Mar 24, 2013)

Rocguy said:


> I can't seem to find the answer to my question, which is what lens could I buy for my T4i (or any crop camera) that would give me an equivalent to what the naked eye sees? 24mm? 35mm? Sorry if this has been asked a million times but I'm just curious. I recently got a 50mm, 1.8, and am loving it. I wish my camera had come with this lens! But it has gotten me curious about other prime lenses and I want one that's close to the naked eye.
> 
> Thanks for any help or info.
> 
> P.S. Is the 50mm the naked eye equivalent for a FF camera?



Do you have borders in your vision? I for sure don't and no matter how close I get to objects, no distortion happens either. 50mm on FF appears to be a tele indoors if compared to what your eyes see. Looking through the viewfinder only gives you a small fraction of the view you get when you move the camera off your face. This is what people claim as "naked eye equivalent" for some reason though. I don't think there is a lens that gives you the same framing as your eyes.


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## Rocguy (Mar 24, 2013)

shashinkaman said:


> Thank god there are only 6 million websites in existance where you easily can find the answer to such questions....! Jeez, some people are really laaaaaaaazy!



Actually I couldn't find the answer on the 6 million websites which is why I asked here. But thank you for being helpful by replying! I love the kindness of strangers.


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## Pi (Mar 24, 2013)

Dick said:


> I don't think there is a lens that gives you the same framing as your eyes.



Fisheye lenses get very close.


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## Rocguy (Mar 24, 2013)

Dick said:


> Rocguy said:
> 
> 
> > I can't seem to find the answer to my question, which is what lens could I buy for my T4i (or any crop camera) that would give me an equivalent to what the naked eye sees? 24mm? 35mm? Sorry if this has been asked a million times but I'm just curious. I recently got a 50mm, 1.8, and am loving it. I wish my camera had come with this lens! But it has gotten me curious about other prime lenses and I want one that's close to the naked eye.
> ...



I think part of the problem is the semantics. Obviously you aren't going to get a view exactly like what your eye sees when you look through a small rectangular hole in a box. That would have to be a pretty wide lens. And I think someone else mentioned our vision is more fisheye too. But I'm definitely not looking for a super wide fisheye lense. Lol 

What *I* mean when I say I'm looking for something "naked eye equivalent" is I'm looking for something that isn't zoomed. Maybe a better way of putting it is true focal distance? If an object is 3 feet in front of me when I look through the lens what will make it appear 3 feet in front of me. Not zoomed in and close up. 

But without knowing the exact wording of what I was looking for it seems other people know what I meant. And I appreciate the answers. It seems that the 24, 28, or 35mm lenses are what I am looking for, with slight variations on each of them as to exactly how close to "normal" vision they would give me. I know now what items I can start looking and adding to my wish list so I can start playing around. Thanks again for the helpful answers everyone. 

As someone that is new to photography and dslr photography the information on the 6 million websites can be daunting and confusing to sift through. I really appreciate forums like this where I can ask a question to people with more experience and knowledge than I have. It's easier and more helpful to sift through 30 or 40 answers then 6 million websites. ;D


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## agierke (Mar 24, 2013)

the field of view of the human eye is near impossible to replicate without introducing change in perspective and compression/expansion of space. the way a camera "sees" vs the way the human eye "sees" is remarkably different.

there is a neat little trick to find a focal length on a particular camera that replicates the "way you see" without consideration to field of view (which is unfair to try to compare). using a mid level zoom, place your camera in a vertical position and look through the viewfinder so that your other eye is not blocked. with both eyes open, zoom the lens in and out until what you see through the lens matches what your other eye sees. take note of what the final focal length was on the zoom. that is the focal length that matches your vision on that particular camera.

i have seen this number vary depending on the camera system used but it can fall between 45mm and 55mm. on my Mrk2 w 24-70mm attached it falls on 55mm. granted its a narrower field of view than human vision but so are most focal lengths depending on how you frame the argument. this method will match how we see spatial relationship of a scene though.


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## Pi (Mar 24, 2013)

Rocguy said:


> If an object is 3 feet in front of me when I look through the lens what will make it appear 3 feet in front of me. Not zoomed in and close up.



That is a different question and depends on the viewfinder of your camera but does not affect the photos you take. 

I guess, what you really wanted to ask  is which FL will give you the same view when you look at the print or at the photo on your monitor. And that depends on the viewing distance, as simple as that. Stick your nose into a large print, and the answer is a 15mm fisheye. Hold a 4x6 print at 60cm viewing distance, not something unusual, and the answer would be 144mm.


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## TrumpetPower! (Mar 24, 2013)

agierke said:


> with both eyes open, zoom the lens in and out until what you see through the lens matches what your other eye sees. take note of what the final focal length was on the zoom. that is the focal length that matches your vision on that particular camera.



Eh, not so much.

All you're doing there is measuring the magnification of the viewfinder -- something that varies from camera to camera and has much more to do with viewfinder coverage area (only 100% in high-end models) and how far away from the viewfinder you can hold your eye and still see the whole thing.

Oh -- and modern viewfinders generally suck royally compared with the days of classic manual focus SLRs such as the Pentax ME-Super.

Cheers,

b&


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## Sporgon (Mar 24, 2013)

There have been some very good points made here, and some confused ones. The whole subject of " what the eyes see" is of great interest to me because we spent a long time at Building Panoramics creating a technique called "Eye's View" for our pictures which we generally take of ancient monuments, both preserved and ruinous.

As I said in my earlier post, the eyes do not see. The brain sees. The reason people can have hallucinations, or see ghosts is that the brain sees these things. To the people topping up on magic mushrooms what they see _is_ real - to them.

The eyes have a field of view, yes, but it is difficult to define as our peripheral vision is a little ill defined - literally. Because a camera ( normally ) takes one exposure with one lens to record a scene, it is in fact very limited when it comes to try and record the view we see, because we are looking around us, subconsciously mapping the info, so our brain then fills in the missing info - a little like the principle of how a tv cartoon works. 

You can test this for yourself. If someone takes you into a place strange to you with your eyes closed, and then, once there you open your eyes and look straight ahead you will find out that your actual field of vision is less wide than you have come to accept. Because you have no reference to what is on either side of you your brain cannot fill in the detail to your field of view. it's a bit weird actually, but in a view seconds you will involuntarily glance around. 

It the same thing with perspective. People say ' ah-ha, when I look at something really close up I don't get the distortion of an ultra wide lens. No you don't because your brain knows what it should look like, but again you can try and test this for yourself. Find something that sticks out such as a door knob or someone's nose etc. Put you eye right up to it real close, close your eyes and try and empty your brain of though. ( Some will find this easier than others - those who post about 6 million pages etc should find it real easy ). Now open your eyes and look at the object and you may briefly see the very distorted perspective from being so close.

The picture of Beverley Minster below is a good example of this. The nave and transept look like the angle between them is less than 45*, ie V shaped. 'This is perspective distortion from the wide angle lens ' you say. But actually we didn't use a wide angle but a 50mm, shot in our 'eye's view' technique. The V shape is the result of how close we had to be to the subject. When you go and stand there you don't see this V because you _know_ it's a 90* turn. However if you stand there with your eyes closed, let you mind go blank, and then open your eyes you will see the V before your brain adjusts to correct everything.

Digital has made it possible to replicate how we see things, but it takes a lot of post processing. The picture below was taken using our 'eyes view' technique, which was done by not only stitching, but also exposure and lens focal length stacking to get both the field of view and perspective the same as we see it.

I've added another copy with the 28mm framing added, so you can see just how wide a shot this is, as well as the 50mm framing which was done in various parts of the picture. This takes a lot of work in putting it together. ( Not these focal lengths refer to FF). The result is really like being there.

But to cut to the chase, as others have said: on your APS-c about 30mm will give the perpective as you see yourself, and about a 22mm will give a field of view close to your _direct_ vision.

Hope this is of interest: try and find this on 6 million websites ;D


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## rpt (Mar 25, 2013)

TrumpetPower! said:


> Oh -- and modern viewfinders generally suck royally compared with the days of classic manual focus SLRs such as the Pentax ME-Super.
> 
> Cheers,
> 
> b&


+1000

I would kill to get the AE1 viewfinder on my 5D3!


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## rpt (Mar 25, 2013)

Sporgon said:


> Hope this is of interest


Very informative. Also lovely pictures. I love your architectural shots. It feels like I am actually being there.


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