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Author Topic: Wide-Angle Lenses and perspective  (Read 1245 times)
Ray
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« on: September 04, 2009, 10:48:19 PM »
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I noticed a recent thread which gravitated towards this topic was closed because of rising tempers and inferred insults. This is my attempt to try to explain what's going on and why both sides of the argument could be considered correct, but each from its own perspective (pun intended).

There's no doubt that a wide-angle lens can create an appearance of an unnaturally enlarged foreground, compared with the size of the objects in the background. Likewise, a telephoto lens can create the opposite effect of appearing to exaggerate the closeness of objects in the background, such as a mountain immediately behind the subject that looks so close but is actually quite far away.

From a subjective point of view, perspective is all about the eye/brain attempting to work out the distances of objects in the picture by assessing their relative size to each other. In order to do this, one has to be able to recognise what the object in the picture actually is. A picture of unrecognisable objects becomes effectively an abstract and as a consequence perspective tends to become less of an issue, although it's alway apparent that any object which appears to be partially obscured by another object must obviously be behind and further away than the object which does the obscuring.

The following shot was a sort of joke snapshot of a fellow traveller in Nepal who seemed rather fascinated with the unusual shape and bulk of my Sigma 15-30mm zoom with protruding, bulbous front element. I explained it was an ultra-wide-angle lens, and took the following portrait with the front of the lens about a foot from his face, which he found rather amusing as you can see.

[attachment=16397:15mm_portrait1743.jpg]

I used a 5D. But supposing I had used a P&S camera with 15mm lens from the same distance. That would not have been wide angle, but medium telephoto. All I would have captured would have been the guy's nose. I would not be able to assess whether or not the guy's nose appears unnaturally large in relation to the rest of his face, and the background, because the rest of the face would not have been in the picture. Large and small are relative terms.

If I had had the patience to do a 20 image stitch with the P&S camera with 15mm lens, of this subject, (assuming the subject were able to remain perfectly still which of course would not have been possible), then the resulting stitch would have looked identical in terms of perspective as the single shot with the 5D and 15mm lens, ignoring lens defects such as distortion. It would differ, of course, in terms of DR, tonality, noise and resolution etc, but not in terms of perspective.

The question now arises, can both images, the single shot with the 5D and the stitched shot with the P&S, both using the same focal length of lens from the same distance, be considered as a distortion of perspective?

I would maintain that they can, from the subjective point of view, but not from the objective science of the principles of optics. In these examples of wide-angle or telephoto lens usage, the camera delivers results which the eye can never see, unaided. The perspective therefore appears distorted because in real life we simply don't get such a wide (or narrow) angle of view using our eyes. We're seeing something never seen before, until wide-angle lenses (and telephoto lenses) were developed.

Imagine you are making love to a beautiful lady with a perfectly shaped nose. You're lying on top of her with your face just 6 inches from hers. There's no sense at all that her nose has enlarged in relation to the rest of her face, because the closer you get the narrower your angle of view.

Suddenly, your eyesight is bestowed with the wide-angle capability of a 12mm lens on a 5D. You see everything in the room in clear detail. Your lover's nose appears huge. It's the same size as it was before, but now in relation to everything else you see, it appears relatively huge. Offputting, maybe?
« Last Edit: September 04, 2009, 11:02:34 PM by Ray » Logged
Rob C
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« Reply #1 on: September 05, 2009, 03:10:18 AM »
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Quote from: Ray
[attachment=16397:15mm_portrait1743.jpg]



Imagine you are making love to a beautiful lady with a perfectly shaped nose. You're lying on top of her with your face just 6 inches from hers. There's no sense at all that her nose has enlarged in relation to the rest of her face, because the closer you get the narrower your angle of view.

Suddenly, your eyesight is bestowed with the wide-angle capability of a 12mm lens on a 5D. You see everything in the room in clear detail. Your lover's nose appears huge. It's the same size as it was before, but now in relation to everything else you see, it appears relatively huge. Offputting, maybe?




Dear God, Ray!

Now, at last, I understand the fascination with oriental transvestites: you will never have to face (groan) that situation ever, never, again!

But from the photographic perspective - oh dear - the thing has nothing to do with wide-angle lenses nor any other kind of glass: perspective is totally due to the viewer's/camera's location vis a vis the subject. Exactly as you pointed out with your comparison between two cameras. In essence, you could only think of wides and perspective as distortions of the one caused by the other if you either did not know that lenses have nothig to do with it or were simply  trying to stoke fires within the tinder-dry forest of LuLa.

Devil's advocate, you!

Rob C
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Ray
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« Reply #2 on: September 05, 2009, 07:28:11 AM »
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Quote from: Rob C
Dear God, Ray!

Now, at last, I understand the fascination with oriental transvestites: you will never have to face (groan) that situation ever, never, again!

But from the photographic perspective - oh dear - the thing has nothing to do with wide-angle lenses nor any other kind of glass: perspective is totally due to the viewer's/camera's location vis a vis the subject. Exactly as you pointed out with your comparison between two cameras. In essence, you could only think of wides and perspective as distortions of the one caused by the other if you either did not know that lenses have nothig to do with it or were simply  trying to stoke fires within the tinder-dry forest of LuLa.

Devil's advocate, you!

Rob C

Rob,
First let me dispel any notion that I might have any sexual proclivities for transvestites. I have photographed them in Thailand because they wish to be photographed and because they are easy to photograph because they are so proud of their transformation from male into female and are not shy to show off the results. In a sense, transvestites, or perhaps more correctly, transexuals, are walking works of art; a product of the surgeon's knife and hormonal treatment. I make no moral judgement here. The idea might be repulsive to some. However, when I show my transexual shots to others, they often cannot believe that they are actually looking at a bloke, when I tell them. It's almost like, "I can't believe it's not butter"   .

To get back to perspective, it seems to me there is a lot of confusion about the naked eye's true focal length and field of view. I get the impression from a Google search that it's about 22-24mm with an FoV of 140-160 degrees. Some reports place it at 180 degrees, but the problem here is peripheral vision. If one includes peripheral vision in the field of view, human vision may be as wide as an ultra-wide-angle lens.

However, peripheral vision is only good for detecting movement and very rough degrees of light and shade. The angle of view of human vision that takes in full detail, or sufficient detail to make accurate perspective assessments, is actually quite narrow. At least mine is. Perhaps I'm abnormal.

There's also the psychological aspect of the brain being familiar with certain results, through habit. We are not objective creatures (or robots), automatically adjusting our perceptions precisely according to distance to subject.

Devil's Advocate or not, I still think that wide-angle lenses create an appearance of distorted perspective because they provide perspective detail in that peripheral area of human vision that normally lacks such detail.

If we turn to the telephoto effect, a similar principle applies, but to opposite effect. The naked eye takes in a wider FoV, in full detail and excluding peripheral vision, that the camera shot does not provide. We therefore get the impression from the photographic image that the distance between foreground and background has been compressed.
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