Human Eye Focal Length
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boojum
Ignoble Miscreant
I observe this effect with an effective 43mm with one eye at the EVF and the other open: binocular vision. Nice. This is so on the X2D + XCD 55V but not so on the M240 + CV 40mm f/1.2 and EVF. With the M240 + EVF the image is smaller and does not match the image of the seeing eye not on the EVF. This is with both cameras at the same position viewing the same scene.
agentlossing
Well-known
This is also relative to the magnification in the viewfinder, isn't it?
boojum
Ignoble Miscreant
Yes, this is the case in this instance and I would guess in all cases.
JohnGellings
Well-known
Well, not all EVFs are the same size, so you are right that will make a difference in using both eyes. However, it should not change the push or pull I am talking about.
Mos6502
Well-known
When I didn't understand what "perspective" really is, and how it works, I used to think that ultrawide angle lenses were more "natural". After all, our field of view is, it seems, very wide. However, I quickly noticed that images taken with wide lenses, 20, 24mm, didn't actually look natural when printed. When I took a drawing class, the reasons why became readily apparent the first time I had to draw a cramped interior, a stairwell. It was quickly demonstrated, in a practical manner, that a lot of how wide we see is a result of us moving our eyes, in other words our natural perspective is not fixed. And if you have to draw it, as you see it, you have to abandon straight lines. Aside from the fact that the wide angle of view we "think" in is not fixed, the other more obvious difference is we (well most of us anyway) see out of two eyes, our natural perspective is actually two very slightly different perspectives.
If you have to see the world through a fixed point, without moving your head, and without moving your eye - indeed the angle of view you can clearly, and comfortably see becomes much narrower. Within the confines of linear, single point perspective, your eye sees something that's more or less equivalent to a 40-45 mm lens on 35mm film.
What's particularly interesting about this is we can see it in action. Next time you're at an art museum, pay attention to where people stand to take in paintings. It is almost always at a distance roughly equal to the diagonal of the painting. The bigger the painting, the further people stand to take it all in. Sure you can walk right up, zoom your eyes around and get the whole thing in your vision, but try that again and again, and you very quickly realize that you do not see as wide as you think you do!
If you have to see the world through a fixed point, without moving your head, and without moving your eye - indeed the angle of view you can clearly, and comfortably see becomes much narrower. Within the confines of linear, single point perspective, your eye sees something that's more or less equivalent to a 40-45 mm lens on 35mm film.
What's particularly interesting about this is we can see it in action. Next time you're at an art museum, pay attention to where people stand to take in paintings. It is almost always at a distance roughly equal to the diagonal of the painting. The bigger the painting, the further people stand to take it all in. Sure you can walk right up, zoom your eyes around and get the whole thing in your vision, but try that again and again, and you very quickly realize that you do not see as wide as you think you do!
pgk
Well-known
Hmmmmm. Despite this 50mm lenses are far more popular as 'standrad' lenses except for those of us who prefer 35mm. Despite many makers producing 40~45mm lenses these have never usurped either 50mm or 35mm in terms of popularity so again, I'm not sure that the 'equivalence' of what we might see has anything much to do with our choice of camera lenses.
JohnGellings
Well-known
Mos6502
Well-known
Popular, or simply most common? 50mm of course is easier to design for a variety of reasons... increasing the focal length is an easy way to increase corner sharpness. As well, 50mm affords space for a swinging mirror in an SLR. It was difficult, if not impossible, to make a 40, or even 45mm lens faster than f/3.5 for early 35mm SLRs. So 50 it was.
We should not forget however, that for several decades 45mm was the most common FL for fixed lens rangefinders, and possibly even the most popular FL for 35mm cameras overall given such cameras as a group greatly outsold SLRs and interchangeable lens RFs.
TenEleven
Well-known
You are not wrong, but I think it's a bit much to insinuate that 50mm was developed for "swinging mirrors" for SLRs when basically the first 35mm camera ever - the Leica null series and then later the Contax after it came out with 50mm lenses.
The Leica even had a 50mm, or rather 5cm lens permanently fitted in its first few iterations. The Contax I similarly came not just with one but with 3 versions of a 50mm lens when it debuted. (The Tessars 3.5 and 2.8, as well as the Sonnar f2, the f1.5 came later) A fast semi-wide was available with the 40mm Biotar that got shortly replaced by the now-famous 35mm Biogon.
Thus, I think it is also worthwhile to check the language of period (1930s and such) photographic catalogues. You will see that they refer to 35mm lenses "wide angle" or even as a "large wide angle" and then, with the introduction of the first 28mm lens, refer to it as "ultra wide angle" or "extreme wide angle". One should also consider that large format and wide-angle lenses for LF had already existed for the better part of 50 years at this point in time. Retro-focal (as for SLR) construction had been known for a similarly long while, what made it difficult for SLRs was that the lens had not only to be retro-focal, but had to be sufficient bright with good contrast and little astigmatism in order to obtain a useful focusing screen image on ground glass.
In short, I think this is less down to technical reasons, although it is unarguably harder to make a fast wide-angle lens, and more due to how society as a whole was used to "see". Our collective perception of what constitutes "normal" perspective, has significantly shifted as time went on. Smartphones with their wide angle lenses probably also played a big role in "naturalizing" a 28mm and nowadays even wider perspective. IIRC recent iPhones even pushed the envelope of "normal" even further all the way down to 24mm.
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Mos6502
Well-known
I don't think I can agree. One only has to look at the endless assortment of "6x6" medium format cameras, made pre-WW2, and fitted with 75mm lenses (which are actually slightly wide, when compared to the diagonal of a square medium format frame). Indeed 85 and 90mm lenses are quite unusual for (square) medium format in any era.
I also have to point out, for clarity, that I never suggested 50mm lenses were developed as a result of SLRs, just that it is easier to design a fast 50mm lens that clears an SLR mirror than it is to design a fast 40mm lens that clears an SLR mirror. In all probability, had the consumer level SLR not caught on, 45mm would have been reigning champion of "normal" focal lengths for 35mm film, as 50mm appeared to be well on its way out by the start of the 60s. 50mm was relatively rare on anything except interchangeable lens systems.
I also have to point out, for clarity, that I never suggested 50mm lenses were developed as a result of SLRs, just that it is easier to design a fast 50mm lens that clears an SLR mirror than it is to design a fast 40mm lens that clears an SLR mirror. In all probability, had the consumer level SLR not caught on, 45mm would have been reigning champion of "normal" focal lengths for 35mm film, as 50mm appeared to be well on its way out by the start of the 60s. 50mm was relatively rare on anything except interchangeable lens systems.
TenEleven
Well-known
You appear to be completely have missed my argument, perhaps I was not being succinct enough:
I was arguing that the view which we accept as normal (due to being exposed to photography in advertisement, news, movies, media etc.) has gradually shifted towards more wide-angle centered way of seeing the world. I don't think that this is really debatable.
Lastly, I have not made mention of medium format anywhere in my post.
Regardless there were only very few makers of TLRs before the war (Namely Franke & Heidecke and belatedly Voigtlander from which they had come as well as some scant few Japanese and perhaps European copies thereof. The real deluge started after the war.) Also most of the 6x6 cameras before the war were folders, where 80mm as a focal length was just as, if not more common. Even so, 75mm or 80mm are both very close to the diagonal of the image circle, a focal length where Tessar lens designs (which most of these are) perform at their best. And as someone who has TLRs of both focal length -- besides the extra depth of field, which is welcome, I find the difference in view to be academic.
I was arguing that the view which we accept as normal (due to being exposed to photography in advertisement, news, movies, media etc.) has gradually shifted towards more wide-angle centered way of seeing the world. I don't think that this is really debatable.
Lastly, I have not made mention of medium format anywhere in my post.
Regardless there were only very few makers of TLRs before the war (Namely Franke & Heidecke and belatedly Voigtlander from which they had come as well as some scant few Japanese and perhaps European copies thereof. The real deluge started after the war.) Also most of the 6x6 cameras before the war were folders, where 80mm as a focal length was just as, if not more common. Even so, 75mm or 80mm are both very close to the diagonal of the image circle, a focal length where Tessar lens designs (which most of these are) perform at their best. And as someone who has TLRs of both focal length -- besides the extra depth of field, which is welcome, I find the difference in view to be academic.
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pgk
Well-known
Which of course leads onto the next question, being: "what format ration do we 'see' in?". I think that both focal length and format preferences are a result of exposure to numerous photographic images rather than anything else. I personally do not use and do not have any 40-45mm lenses as these are focal lengths which I have no use for (not even a zoom which covers them or their equivalent). I rarely use 50mm (I do have one) and my, by far, most used lens is 35mm. All this tells anyone is my personal preference, nothing more and nothing less, I'm afraid.
Mos6502
Well-known
This doesn't change anything. We're speaking of these matters in general terms. It doesn't matter whether we're talking about 16mm film, or 8x10 sheet film. We're discussing the field of view, which as a function of the focal length in relation to the diagonal of the frame can be applied to any format of any size.
If the 50mm angle of view on 135 film is the "normal" way of viewing things in the era that it first appeared, as you insinuated, then how does one reconcile that claim with the very simple fact that the majority of taking lenses on other formats afforded a wider angle of view? 50mm was very plainly an odd choice in the 1920s, and in the 1930s, and in the 1940s, and in the 1950s, and for most of the 1960s. If we're speaking generally. Only a small portion of cameras made used an equivalent focal length regardless of format. And even in the 1960s, despite the increasing popularity of the SLR, one should keep in mind that millions of Instamatic cameras left the factory with 38mm and 41mm lenses (the diagonal of the Instamatic frame is 39mm) so even then 50mm was still a bit weird, generally speaking, of course.
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Mos6502
Well-known
The aspect ratio is a matter of personal preference, of course. But here's the cool thing about that in reference to perspective: it really doesn't matter. Whether the image is square, or panoramic, the "natural" view will be obtained while viewing the image from a distance roughly equal to the diagonal of said image. And thus, the "natural" perspective within the image itself will be obtained with a lens of a focal length roughly equal to the diagonal of the frame the lens projects upon.
As regards your favored focal length, it is important to remember that perspective is a function of camera position. This is why people get the idea that wide angle lenses "force" perspective. Because to make up for a wider angle of view, the photographer moves the camera into a position closer to the subject. A wide angle lens used from the same position as a normal lens gives an identical perspective (as does a long lens).
It is actually too bad Roger Hicks is not here for this discussion, he wrote a good explanation in one of his books if I recall correctly.
titrisol
Bottom Feeder
This lens (besides being wonderful) is closer to how I see things (sharply)
Our eyes are much wider angle but the area that is sharp at all times is around a 40-45mm lens for me
jchfriis
Established
My most used focal length is 40 mm (on so-called full frame). And that is because my most used camera for many years was a Rollei 35. I got used to that focal length so I’m comfortable with it. I guess that’s what the sensor in my brain tells me.
boojum
Ignoble Miscreant
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)
Please say "yes" as I am sitting here thinking I am pretty damned smart and would hate to have the illusion disturbed. ;o)
wes loder
Photographer/Historian
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. Serious and professional 35mm cameras came with 50mm (or close) as their normal lenses [some SLRs used 55mm or even 58mm since it was easier to design a high-speed lens for a SLR with a longer focal length]. Later amateur and cheaper cameras used shorter focal lengths—not because that was a more "natural" focal length—but because the greater depth of field and easier framing compensated for lesser skills. There is a sweet spot for designing focal lengths that cover 35mm or larger formats. A 95mm lens on a 6X6 format camera would give a closer equivalent to the 50mm lens for 35, but now you are talking more weight and size if one wants higher speed. The 80mm focal length was a compromise of speed and size. It is simply easier to design a 50mm focal length for the 24x36 format and gain speed than go with focal lengths that are a lot shorter.
ChrisPlatt
Thread Killer
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
And my eyes don't take still photos; do yours?
Chris
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