LeonardLeo Loc: Warren Michigan

And
... Is photography art or science?

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Matters verrrrry slightly as to who you ask. Matters greatly as to who’s asking.

IOW, the question is worth about zero, and an answer is worth somewhat less.

David in Dallas Loc: Dallas, Texas, USA

Art. I agree that the length of the diagonal of a rectangle 24x36 is 43, but I don't see why the length of the diagonal should be the size designated as "normal" or "standard". I'm guessing that the lens size that seems to depict what the eye sees just happens to be close to that value, so that rule was adopted--not that there was any good physical reason to do so. The structure of the eye certainly does not give a reason for that rule.

The fovea (small circle of greatest detail) is only 1.5mm in diameter. Since it's circular, 1.5mm is also it's diagonal. The macula (area of high definition) is 5mm. It has been posted that the eye's FL is about 17mm, which is about 1/3 that of 50mm ("normal"). If we were to expand the macula in proportion to that FL we'd get a diameter of about 15mm, and that, in turn is about 1/3 of the diagonal of a 35mm film frame. That would suggest that a 150mm lens would put on a 35mm frame an image that more or less corresponded with what is intercepted and recorded by the macula. Obviously, that flies greatly in the face of the common "wisdom", and so there must be more to the matter. In reality, the number of rods (B&W vision) declines from that in the macula in a relatively smooth manner--the total field of view (FOV) of an eye is about 155° wide by 130° tall, but a lot of that has only limited definition (fewer rods--the cones are almost all in the macula). The way the brain interprets the signals from the eyes has a lot to do with perception.

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R.G. Loc: Scotland

Exactly, and one of the main factors is depth perception. Field of view is one of the more irrelevant factors because our total field of view includes the wide area of low resolution and low detail perception. Thinking in terms of our mentally focused perception puts us in search of a "normal" field of view which doesn't exist - one reason being that it varies considerably between individuals and another reason is that it varies considerably depending on the degree to which we're focusing our attention mentally.

While the changeover from distance compression to distance expansion is very gradual and doesn't have a clearly defined crossover point, it's probably one of the more consistent factors that affect our perceptions and that are dependent on lens focal length (and format).

Bankshot Loc: Henderson, NV, USA

The simple answer to this question is found by experimentation with YOUR camera and lens. Not all cameras and lenses and eyes are the same. Put a zoom lens on your camera that allows for focal lengths around 50-70mm. Put the camera to one eye in such a way that you can view the same scene with your other eye, and zoom the lens until you see the same thing (one focused image) with both eyes, and look to see what the focal length is on your camera. My Tamron zoom on my D7200 says 55-60mm. Your results may vary! My old Ricoh 35mm with the 55mm lens was just about perfect at eye equality.
Bill

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You are waaaaaaay off-topic. You’re not discussing FoV or FL or even the vague notions of perception and attention. You are discussing viewfinder design. Thaz a very hot topic for some other thread but absolutely meaningless here.

If some lens for some format could be accepted as rendering close to human vision, it wouldn’t matter in the least what sort of viewfinder is used to help aim it at a subject. The lens renders exactly the same whether aimed by squinty peephole, open wire frame, or five foot tethered monitor.

Bankshot Loc: Henderson, NV, USA

Sorry, but the question was What MM lens to capture an image the way our eye sees it.

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Quite so. Which has nothing to do with the viewfinder image that a camera delivers to your eye. Whatever FL lens captures an image as our eye sees it will be that FL lens even when used with no viewfinder at all.

The question all along is “What FL lens sees most like a human” ... and NOT “What FL lens sees just like the VF in bankshot’s old Ricoh”.

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Thaz a very vague experiment.

Just look at your results. You have about 300% discrepancy in fields of view that are supposed to each be like human vision. You have both mild wide angle (Ricoh 35, film) and short telephoto (ASPC dslr).

Using FF as a common denominator, you have both a 35 and a 90 as similar to human vision. There is value in that. 35 represents a human looking around casually, attention not focused. Same human paying attention to a face or object of interest would be well represented by the 90.

While any human easily scans much wider than 35mm, lenses that wide do not render images with a human-vision-similar look. The “wide lens look” can start to creep in around 28mm.

Likewise a human will easily narrowly focus their attention in a manner much narrower than a 90mm lens. But again you cannot render that photographically in a manner similar to human vision. Lenses longer than the 90 or “portrait” lengths tend deliver that “tele lens look”.

So avoiding the long lens or short lens “look” keeps you between about 35 and 90. Human field of visual attention, casually wide or more attentively narrowed, is pretty well represented within that 35 to 90 FL range. Clearly our typical “normal” FL lenses really are verrrrrrry normal. Acoarst thaz why eager noobies avoid them ... and that is also very “normal” :-)

Bankshot Loc: Henderson, NV, USA

A guy with no name, no location, and no birthday want's to argue with me! OK, USER ID , you win, is that what you want F-off!

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Seems you’ve been snagged by an AI bot. Remarkably careless. Beautiful specimen.