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Topic: Perspective distortion caused by lens focal length

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Perspective projection distortion

Perspective distortion

	Perspective projection distortion - Wikipedia, the free encyclopedia
		Figure 8 shows that the perspective projection of the horizontal top line of the wall intersects at the retina (actually, in true life, at the focal point slightly in front of the retina and from where it is inverted).
		Mathematically, the difference between artificial perspective projection (perspective projection onto a flat surface) and natural perspective projection (perspective projection onto a spherical surface) is a distortion resulting from the small-angle approximation which results from projecting onto a flat surface.
		In an artificial perspective projection, every car on the road would be drawn at the same size, even though it is clear in reality that the farther away from the center of the picture that a car is, the farther away from the viewer that car would be.
	en.wikipedia.org /wiki/Perspective_projection_distortion (2112 words)

	Photography - Wikipedia, the free encyclopedia
		The aperture is expressed by an f-number or f-stop (derived from focal ratio), which is proportional to the ratio of the focal length to the diameter of the aperture.
		In addition to the subject or camera movement that might vary depending on the shutter speed, the aperture (and focal length of the lens) determine the "depth of field," which refers to the range of distances from the lens that will be considered in acceptable focus.
		For example, using a long lens and a large aperture (f/2.8, for example), such as might be used with a large format camera, a subject's eyes might be in sharp focus while the tip of the nose is noticeably blurred.
	en.wikipedia.org /wiki/Photography (5288 words)

	Understanding Camera Lenses
		The focal length of a lens determines its angle of view, and thus also how much the subject will be magnified for a given photographic position.
		The focal length of a lens may also have a significant impact on how easy it is to achieve a sharp handheld photograph.
		A zoom lens is one where the photographer can vary the focal length within a pre-defined range, whereas this cannot be changed with a "prime" or fixed focal length lens.
	www.cambridgeincolour.com /tutorials/camera-lenses.htm (2050 words)

	Photography - Facts, Information, and Encyclopedia Reference article
		Focal length of the lens (telephoto, macro, wide angle, or zoom)
		The controls are usually inter-related, for example brightness is aperture multiplied by shutter speed, and varying the focal length of the lens will allow greater control over the depth of field.
		Len Bernstein has described the Aesthetic Realism understanding of photography as an art form in essays which have been published for example in Apogee Photo Magazine and in Photographica World: The Journal of the Photographic Collectors Club of Great Britain.
	www.startsurfing.com /encyclopedia/p/h/o/Photography.html (3083 words)

	Perspective (graphical) - Hutchinson encyclopedia article about Perspective (graphical) (Site not responding. Last check: 2007-10-13)
		In painting and drawing, the application of perspective to a single object or figure to create the illusion of projection or depth.
		It mimics the shortened appearance of a form when it is not perpendicular to the line of sight, for instance an arm held out to the viewer will look shorter, and the hand larger, than an arm held straight down by the side.
		Although the figures are very short, the use of perspective enables the viewer to recognize that in real life they would be taller.
	encyclopedia.farlex.com /Perspective+(graphical) (224 words)

	Handling Distortion and Perspective Errors in Imaging Systems - Archives - Quality (Site not responding. Last check: 2007-10-13)
		Distortion is an optical error or aberration, caused by the lens, which results in differences in magnification at different points in the image.
		Perspective also exists in conventional imaging systems, in which the magnification of the object changes with its distance from the lens.
		Perspective errors are most troublesome in measurement applications involving objects with depth or objects moving relative to the lens.
	qualitymag.com /CDA/Archives/f02e79be55c38010VgnVCM100000f932a8c0____ (568 words)

	Camera Equipment Forum: Is Perspective distortion dependent on Format or only on focal length ?
		Perspective depends only on where your camera is in relation to the subject.
		But if you shoot from the same position with a wide lens and then with a telephoto lens, you will see that the perspective is actually identical (you have to crop the wide-angle shot to match the field of view of the telephoto lens).
		As the lenght of a lens increases you go from "expansion" to "compression" with the "normal" lens being the one that gives a FOV appx equal to the human eye for the given film/sensor size.
	www.photo.net /bboard/q-and-a-fetch-msg?msg_id=00A5AU (1220 words)

	Telephoto
		In photography and cinematography, a telephoto lens is a lens where the focal length is significantly longerthan the focal length of a normal lens.
		For a 35 mm camera with a 36 mm by 24 mm format, the normal lens is 50 mm and a lens of focal length 70 mm or more is considered telephoto.
		This effect is similar to moving closer to theobject, but is not the same; see perspective distortion caused by lens focal length.
	www.lottery-news.net /dust29431-telephoto.html (276 words)

	Frequently Asked Questions Regarding Lenses
		A 50mm lens produces an image of a distant object on the film that is the same size as would be produced by a pinhole 50mm from the film.
		The focal length of the lens divided by the diameter of the aperture (as seen from the front).
		Light passing through the edge of the lens is focused at a different distance (closer in simple lenses) than light striking the lens near the center.
	www.graflex.org /lenses/lens-faq.html (3582 words)

	Hitchcock zoom - TheBestLinks.com - Alfred Hitchcock, Martin Scorsese, Robert De Niro, Special effect, ... (Site not responding. Last check: 2007-10-13)
		In the Hitchcock zoom, the setting of a zoom lens is used to adjust the field of view at the same time as the camera moves towards or away from the subject in such a way as to keep the subject the same size in the frame throughout.
		Thus, during the zoom, there is a continuous perspective distortion caused by lens focal length, the most directly noticeable feature of which is that the background "changes size" relative to the subject.
		As the human visual system uses both size and perspective cues to judge the relative sizes of objects, seeing a perspective change without a size change is a highly unsettling effect, and the emotional impact of this effect is much greater than the description above can suggest.
	www.thebestlinks.com /Hitchcock_zoom-bp-redirect-v-no-ep-.html (360 words)

	Perspective distortion (caused by camera to s... - Wikipedia, the free encyclopedia
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	en.wikipedia.org /wiki/Perspective_distortion_(caused_by_camera_to_s... (184 words)

	Epinions.com - Fixed Focal length Lenses are Glorious, The Best Zoom Lenses are Divine!!!
		All the major camera makers have made many of them in various focal lengths in years past but there are even differences in quality between FFLLs with different maximum apertures from the same manufacturer.
		Rectilinear means that the lens is well corrected not to distort when held parellel to a building face or perpendicular to the floor as a reference.
		The 17 mm lens on a partial-frame digital SLR will equate to a 24 mm wide angle lens on a full-frame 35 mm format, but 17 mm glass is much more affordable than 14 mm glass.
	www.epinions.com /content_2591072388 (2229 words)

	Lens Faults Hierarchy (Site not responding. Last check: 2007-10-13)
		When the lens is stopped down this haziness dissapears, due to the reduction in spherical aberration from the outer parts of the lens, and the point of best focus seems to move toward the lens by a little.
		The Mamiya 50mm non-"C" lens is indeed a single-coated lens.
		Also, because each element in a wide angle lens have to bend the light at such a radical angle the bigger the front lens element is, the less of the edge of the element you have to use and the edge of the lens elements are optically the worst.
	medfmt.8k.com /bronfaultsp.html (19636 words)

	Canon 50/1.8 Lens
		The lens is plasticky, it has no distance scale (I wonder how often people use it though, I know I will miss it only for flash photos in manual), no metal mount, and no proper focus ring.
		The operation has had no discernable effect on my lens performance other than to improve clarity, but a disclaimer nonetheless: Do not try this at home if you are fumble-fingered, mechanically-challenged, or this is the only lens you own and can not afford a replacement.
		Lens Quality Part 2: Normal Lenses (50 mm)- This site compares the optical performace of the EF 50mm f1.4 USM and the EF 50mm f1.8 II lenses.
	photo.net /photo/canon/canon-50-1.8.html (4901 words)

	Lens for full length portraits [Archive] - Canon Digital Photography Forums
		My only concern is that there will be no distortion to the face, but as I am shooting the whole person and not just their face / shoulders I assume there wont be that effect to the face.
		If you need a lens shorter than about 31mm, I would expect to see some "distortion" because of the perspective caused by being close to the subject.
		I routinely use lenses in the normal focal range, or slightly longer, for full-length portraits, particularly at weddings where quarters are often cramped.
	photography-on-the.net /forum/archive/index.php/t-105738.html (1002 words)

	ihtchcock information,hitchcock (Site not responding. Last check: 2007-10-13)
		In the ihtchcock zoom, the setting of a zoom lens is used to adjust the field of view at the same time as the camera moves towards or away fromthe subject in such a way as to keep the subject the same size in the frame throughout.
		Thus, during the zoom, there is a continuous perspective distortion caused by lens focal length, the most directlynoticeable feature of which is that the background "changes size" relative to the subject.
		As the human visual system uses bothsize and perspective cues to judge the relative sizes of objects, seeing a perspective change without a size change is a highlyunsettling effect, and the emotional impact of this effect is much greater than the description above can suggest.
	www.vsearchmedia.com /ihtchcock.html (361 words)

	ImageAlign - Lens Distortion Correction Tool (Site not responding. Last check: 2007-10-13)
		Correcting both lens tilt and curvature distortions, it solves a problem that's as old as the camera, without expensive hardware and even on old photographs.
		The intractable problem of perspective distortion has never been completely solved, even with expensive hardware, so Grasshopper consider this a breakthrough that could well revolutionise two-dimensional imaging.
		When photographing a subject with vertical or horizontal lines, the film plane must be perpendicular to the centre of the subject to avoid converging lines, which make objects seem to lean away from or towards the camera, or make their height change unnaturally.
	www.imagealign.com /news.htm (2421 words)

	Lens for full length portraits - Canon Digital Photography Forums
		Since you have a lens that probably includes the focal length that would suit you best, why not try it and find that "magic" focal length.
		On a 1.6x crop camera the 24-70/2.8L is an extremely versatile studio lens for full length shots.
		Followed the sujestion of using my 18-55mm and different focal lengths, seems for the size of the rooms the best is a 28mm.
	photography-on-the.net /forum/showthread.php?p=857542 (1143 words)

	Perspective Adjustment Lens - ... - lenscrafters.seatbelts.be (Site not responding. Last check: 2007-10-13)
		When you're taking pictures of certain types of subjects, there is a desire to tilt the camera up or down from the horizontal.
		If your perspective control lens has an indicator telling the amount of the...
		The wider the focal length of the lens the greater the distortion (although there are...
	lenscrafters.seatbelts.be /.../perspective-adjustment-lens.html (353 words)

	hitchcoc information,hitchcock (Site not responding. Last check: 2007-10-13)
		In the hitchcoc zoom, the setting of a zoom lens is used to adjust the field of view at the same time as the camera moves towards or away fromthe subject in such a way as to keep the subject the same size in the frame throughout.
		The hitchcoc zoom is commonly used by film-makers to represent the sensation of vertigo, or to suggest that undergoing a realization that causes them to reassess everything they had previouslybelieved.
		A notable use of this effect is in Goodfellas, wheredirector Martin Scorsese uses the hitchcoc zoom in a scene duringthe climax of the film: Henry Hill (Ray Liotta) and Jimmy Conway (Robert De Niro) are sitting in a restaurant, talking.
	www.vsearchmedia.com /hitchcoc.html (361 words)

	David Ruether - SUBJECTIVE Lens Evaluations (Mostly Nikkors) (Site not responding. Last check: 2007-10-13)
		It is my opinion that a lens that is not sharp almost to the far corner of the frame at a particular stop should not be considered sharp at that stop.
		Though all major lens lines have their "gems", for a long time Nikon appeared unique in having the widest range of lens types and also the highest overall quality-level of offerings in its line (including top-quality lenses for all the important focal lengths and types likely to be in a good lens collection).
		Nikon appears to have confused their lens line with the "G" mount, which denotes both their cheapest lenses and their most expensive - and since it removes the aperture ring from the lens, these newer lenses cannot be used on most older camera bodies.
	www.ferrario.com /ruether/slemn.html (5640 words)

	Picture correction & photo distortion correction - digital photo editing software by ImageAlign (Site not responding. Last check: 2007-10-13)
		When you think about it, a lot of your effort in fashion photography is related solely to avoiding the dreaded lens distortion.
		No longer must colours or styles be chosen or avoided for their distorting effect on the subject.
		All the angles, people and architecture so unavoidable in wedding photography are distorted by lens-created aberrations and this single tool takes care of them all in one go.
	www.grasshopperonline.com (1130 words)

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