1272:
1624:
3678:
409:
1205:
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43:
1183:
1171:
1159:
1147:
140:
588:
1607:, camera–lens combinations are often described in terms of their 35 mm-equivalent focal length, that is, the focal length of a lens that would have the same angle of view, or field of view, if used on a full-frame 35 mm camera. Use of a 35 mm-equivalent focal length is particularly common with
1275:
In this computer simulation, adjusting the field of view (by changing the focal length) while keeping the subject in frame (by changing accordingly the position of the camera) results in vastly differing images. At focal lengths approaching infinity (0 degrees of angle of view), the light rays are
624:
in the diagram above). The term "focal length" by itself is ambiguous in this case. The historical usage was to define the "focal length" as the EFL times the index of refraction of the medium. For a system with different media on both sides, such as the human eye, the front and rear focal lengths
399:
lens is somewhat more difficult. The focal length of such a lens is defined as the point at which the spreading beams of light meet when they are extended backwards. No image is formed during such a test, and the focal length must be determined by passing light (for example, the light of a laser
628:
The distinction between front/rear focal length and EFL is important for studying the human eye. The eye can be represented by an equivalent thin lens at an air/fluid boundary with front and rear focal lengths equal to those of the eye, or it can be represented by a
1588:; its angle of view is similar to the angle subtended by a large-enough print viewed at a typical viewing distance of the print diagonal, which therefore yields a normal perspective when viewing the print; this angle of view is about 53 degrees diagonally. For
833:
1600:(typically 85 mm and more, for 35 mm-format cameras). Technically, long focal length lenses are only "telephoto" if the focal length is longer than the physical length of the lens, but the term is often used to describe any long focal length lens.
226:
in which magnification is achieved by bringing the object close to the lens, a shorter focal length (higher optical power) leads to higher magnification because the subject can be brought closer to the center of projection.
1078:
of the mirror divided by two. The focal length is positive for a concave mirror, and negative for a convex mirror. In the sign convention used in optical design, a concave mirror has negative radius of curvature, so
1477:
1040:
952:
625:
are not equal to one another, and convention may dictate which one is called "the focal length" of the system. Some modern authors avoid this ambiguity by instead defining "focal length" to be a synonym for EFL.
1364:
330:
1066:
is negative if the second surface is convex, and positive if concave. Sign conventions vary between different authors, which results in different forms of these equations depending on the convention used.
691:
447:
of the system. The imaging properties of the optical system can be modeled by replacing the system with an ideal thin lens with the same EFL. The EFL also provides a simple method for finding the
1700:
are placed close together their powers approximately add. Thus, a thin 2.0-dioptre lens placed close to a thin 0.5-dioptre lens yields almost the same focal length as a single 2.5-dioptre lens.
1384:
To render closer objects in sharp focus, the lens must be adjusted to increase the distance between the rear principal plane and the film, to put the film at the image plane. The focal length
1592:
35 mm-format cameras, the diagonal is 43 mm and a typical "normal" lens has a 50 mm focal length. A lens with a focal length shorter than normal is often referred to as a
203:
must be located to form a collimated beam. For more general optical systems, the focal length has no intuitive meaning; it is simply the inverse of the system's optical power.
3646:
1118:
390:
339:
lens can be easily measured by using it to form an image of a distant light source on a screen. The lens is moved until a sharp image is formed on the screen. In this case
3593:
2014:
1611:, which often use sensors smaller than 35 mm film, and so require correspondingly shorter focal lengths to achieve a given angle of view, by a factor known as the
222:; conversely, shorter focal length or higher optical power is associated with lower magnification and a wider angle of view. On the other hand, in applications such as
1276:
nearly parallel to each other, resulting in the subject looking "flattened". At small focal lengths (bigger field of view), the subject appears "foreshortened".
584:
For an optical system in air the effective focal length, front focal length, and rear focal length are all the same and may be called simply "focal length".
1411:
957:
869:
3636:
3588:
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The focal length of a lens determines the magnification at which it images distant objects. It is equal to the distance between the image plane and a
255:), the focal length is negative and is the distance to the point from which a collimated beam appears to be diverging after passing through the lens.
400:
beam) through the lens, examining how much that light becomes dispersed/ bent, and following the beam of light backwards to the lens's focal point.
2238:
1381:, by the lens's focal length. Objects far away from the camera then produce sharp images on the sensor or film, which is also at the image plane.
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2028:
1997:
1960:
1898:
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1927:
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1596:(typically 35 mm and less, for 35 mm-format cameras), while a lens significantly longer than normal may be referred to as a
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Camera lens focal lengths are usually specified in millimetres (mm), but some older lenses are marked in centimetres (cm) or inches.
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126:
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3097:
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64:
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For an optical system in a medium other than air or vacuum, the front and rear focal lengths are equal to the EFL times the
107:
3185:
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456:
60:
79:
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more sharply, bringing them to a focus in a shorter distance or diverging them more quickly. For the special case of a
3729:
3714:
3618:
2895:
2397:
3037:
1084:
828:{\displaystyle {\frac {1}{f}}=(n-1)\left({\frac {1}{R_{1}}}-{\frac {1}{R_{2}}}+{\frac {(n-1)d}{nR_{1}R_{2}}}\right),}
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50 mm from the film plane, so that it is at the location of the image plane. To focus an object 1 m away (
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86:
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214:, where the subject is essentially infinitely far away, longer focal length (lower optical power) leads to higher
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2159:
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metre. A flat window has an optical power of zero dioptres, as it does not cause light to converge or diverge.
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683:
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31:
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A lens with a focal length about equal to the diagonal size of the film or sensor format is known as a
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lens (one which has a non-negligible thickness), or an imaging system consisting of several lenses or
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3256:
3251:
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will be positive if the first lens surface is convex, and negative if it is concave. The value of
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has the object distance, image distance, and focal length all as reciprocals. Additionally, when
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1993:
1956:
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1894:
1871:
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1668:
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425:
258:
When a lens is used to form an image of some object, the distance from the object to the lens
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of a positive (convex) lens, a negative (concave) lens, a concave mirror, and a convex mirror.
1989:
1952:
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1573:. This model leads to the simple geometric model that photographers use for computing the
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of a camera; in this case, the angle of view depends only on the ratio of focal length to
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474:
192:
100:
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1,000 mm), the lens must be moved 2.6 mm farther away from the film plane, to
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1709:
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equivalent thin lens that is totally in air, with focal length equal to the eye's EFL.
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196:
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An example of how lens choice affects angle of view. The photos above were taken by a
17:
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1978:
1945:
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1294:
1071:
860:
444:
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252:
244:
236:
219:
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1182:
199:, or alternatively a negative focal length indicates how far in front of the lens a
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200:
184:
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30:"Rear focal distance" redirects here. For lens to film distance in a camera, see
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For a thin lens in air, the focal length is the distance from the center of the
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42:
1204:
1133:
for more information on the sign convention for radius of curvature used here.
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The main benefit of using optical power rather than focal length is that the
432:), there are several related concepts that are referred to as focal lengths:
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2317:
2280:
2275:
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2213:
2196:
1697:
429:
211:
188:
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1779:
Simpson, Michael J. (24 February 2023). "Focal Length, EFL, and the Eye".
1388:, the distance from the front principal plane to the object to photograph
139:
3160:
2975:
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2402:
2270:
2191:
2186:
1719:
1604:
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3200:
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1627:
Illustration of the relationship between optical power and focal length
1472:{\displaystyle {\frac {1}{s_{1}}}+{\frac {1}{s_{2}}}={\frac {1}{f}}\,.}
247:), the focal length is positive and is the distance at which a beam of
1867:
1800:
1035:{\displaystyle {\mbox{BFD}}=f\left(1-{\frac {(n-1)d}{nR_{1}}}\right).}
947:{\displaystyle {\mbox{FFD}}=f\left(1+{\frac {(n-1)d}{nR_{2}}}\right),}
251:
will be focused to a single spot. For a diverging lens (for example a
2747:
2164:
2114:
1640:
191:
in air, a positive focal length is the distance over which initially
163:
system is a measure of how strongly the system converges or diverges
160:
27:
Measure of how strongly an optical system converges or diverges light
1397:, and the distance from the rear principal plane to the image plane
1377:
is separated from the sensor or film, which is then situated at the
587:
1524:), the rear principal plane of the lens must be located a distance
3415:
2830:
2290:
1652:
1622:
1270:
1203:
586:
407:
164:
138:
1846:
Simpson, Michael J. (28 March 2022). "Nodal points and the eye".
1675:, 1 dioptre = 1 m. For example, a 2-dioptre lens brings parallel
1581:. In general, the angle of view depends also on the distortion.
1359:{\textstyle \mathrm {FOV} =2\arctan {\left({x \over 2f}\right)}}
2073:
325:{\displaystyle {\frac {1}{f}}={\frac {1}{u}}+{\frac {1}{v}}\ .}
179:
light, while a negative focal length indicates that the system
2069:
1208:
Images of black letters in a thin convex lens of focal length
36:
443:
of an optical system, and is the value used to calculate the
1561:
distant objects the same size as the lens in question. For
522:) is the distance from the front focal point of the system (
1889:
Hecht, Eugene (2017). "6.1 thick Lenses and Lens systems".
1297:(FOV) of a lens are inversely proportional. For a standard
1074:
in air, the magnitude of the focal length is equal to the
839:
is the refractive index of the lens medium. The quantity
1569:), the imaging of distant objects is well modelled as a
1373:
When a photographic lens is set to "infinity", its rear
1307:
1212:
are shown in red. Selected rays are shown for letters
962:
874:
541:). Some authors refer to this as "front focal length".
357:
is negligible, and the focal length is then given by
183:
light. A system with a shorter focal length bends the
1414:
1087:
960:
872:
694:
580:). Some authors refer to this as "back focal length".
366:
279:
1126:
is the radius of curvature of the mirror's surface.
243:) of the lens. For a converging lens (for example a
3629:
3576:
3481:
3424:
3330:
3214:
3126:
3078:
2818:
2585:
2385:
2107:
451:without tracing any rays. It was previously called
67:. Unsourced material may be challenged and removed.
1977:
1944:
1471:
1358:
1112:
1034:
946:
827:
384:
324:
175:. A positive focal length indicates that a system
439:The effective focal length is the inverse of the
1267:) has a double-size, virtual and upright image.
1235:) has an equal-size, real and inverted image;
606:of the medium in front of or behind the lens (
591:Sketch of human eye showing rear focal length
493:is the distance from the rear principal plane
2085:
1742:
1740:
1738:
1736:
8:
1976:Stroebel, Leslie; Zakia, Richard D. (1993).
1370:is the width of the film or imaging sensor.
1198:camera at a fixed distance from the subject.
3637:Conservation and restoration of photographs
1499:must be increased. For example, consider a
469:is the distance from the front focal point
3374:Comparison of digital and film photography
2092:
2078:
2070:
866:The corresponding front focal distance is:
262:, the distance from the lens to the image
3594:Photographs considered the most important
1465:
1455:
1444:
1435:
1424:
1415:
1413:
1336:
1331:
1308:
1306:
1224:in blue, green and orange, respectively.
1097:
1086:
1015:
985:
961:
959:
927:
897:
873:
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808:
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768:
757:
748:
737:
728:
695:
693:
562:) is the distance from the vertex of the
365:
306:
293:
280:
278:
127:Learn how and when to remove this message
1812:
1810:
1732:
1514:50 mm. To focus a distant object (
1893:(5th ed.). Pearson. p. 257.
1980:The Focal encyclopedia of photography
1774:
1772:
7:
636:For the case of a lens of thickness
65:adding citations to reliable sources
3589:Museums devoted to one photographer
3136:Timeline of photography technology
1651:of the focal length, expressed in
1315:
1312:
1309:
457:35 mm-equivalent focal length
395:Determining the focal length of a
25:
2046:Field Guide to Geometrical Optics
1749:Field Guide to Geometrical Optics
1243:) has its image at infinity; and
195:(parallel) rays are brought to a
3687:
3677:
3676:
1181:
1169:
1157:
1145:
513:The front focal distance (FFD) (
41:
3688:
1113:{\displaystyle f=-{R \over 2},}
52:needs additional citations for
1507:camera with a focal length of
1000:
988:
912:
900:
783:
771:
720:
708:
1:
3186:Painted photography backdrops
3118:Golden triangle (composition)
2393:35 mm equivalent focal length
2044:Greivenkamp, John E. (2004).
1747:Grievenkamp, John E. (2004).
1603:Due to the popularity of the
954:and the back focal distance:
678:, the effective focal length
385:{\displaystyle f\approx v\ .}
2013:Stroebel, Leslie D. (1999).
1131:Radius of curvature (optics)
436:Effective focal length (EFL)
2896:Intentional camera movement
573:) to the rear focal point (
547:Back focal distance (BFD) (
335:The focal length of a thin
3746:
3584:Most expensive photographs
2941:Multi-exposure HDR capture
1947:Practical astrophotography
510:Front focal distance (FFD)
239:to the principal foci (or
29:
3672:
2048:. SPIE Field Guides vol.
1943:Charles, Jeffrey (2000).
1072:spherically-curved mirror
544:Back focal distance (BFD)
455:(not to be confused with
3518:Digital image processing
1048:used here, the value of
500:to the rear focal point
462:Front focal length (FFL)
3191:Photography and the law
483:Rear focal length (RFL)
465:The front focal length
453:equivalent focal length
404:General optical systems
266:, and the focal length
231:Thin lens approximation
3725:Science of photography
3538:Gelatin silver process
2562:Science of photography
2547:Photographic processes
2525:Perspective distortion
1914:Hecht, Eugene (2002).
1817:Hecht, Eugene (2002).
1698:relatively thin lenses
1628:
1473:
1360:
1277:
1268:
1114:
1036:
948:
829:
599:
486:The rear focal length
413:
386:
326:
152:
18:Effective focal length
2996:Schlieren photography
2535:Photographic printing
2458:Exposure compensation
2016:View Camera Technique
1951:. Springer. pp.
1679:of light to focus at
1626:
1474:
1406:are then related by:
1361:
1274:
1207:
1115:
1037:
949:
859:is also known as the
830:
657:), and surfaces with
590:
532:first optical surface
411:
387:
327:
142:
32:Flange focal distance
2780:Straight photography
2418:Chromatic aberration
2023:. pp. 135–138.
1922:. pp. 244–245.
1671:, equivalent to one
1571:pinhole camera model
1412:
1305:
1085:
958:
870:
692:
684:Lensmaker's equation
564:last optical surface
364:
277:
61:improve this article
3647:photographic plates
3332:Digital photography
2510:Hyperfocal distance
2423:Circle of confusion
2052:. SPIE. p. 7.
1860:2022ApOpt..61.2797S
1793:2023ApOpt..62.1853S
1661:unit of measurement
1605:35 mm standard
1559:pinhole that images
1076:radius of curvature
3730:Optical quantities
3715:Geometrical optics
3151:Autochrome Lumière
3146:Analog photography
2971:Pigeon photography
2760:Social documentary
2239:discontinued films
1629:
1565:(that is, with no
1563:rectilinear lenses
1469:
1356:
1278:
1269:
1110:
1032:
966:
944:
878:
825:
659:radii of curvature
600:
414:
412:Thick lens diagram
382:
322:
153:
3702:
3701:
3503:Collodion process
3439:Chromogenic print
3426:Color photography
2936:Multiple exposure
2911:Lo-fi photography
2438:Color temperature
2030:978-0-240-80345-6
1999:978-0-240-51417-8
1962:978-1-85233-023-1
1900:978-1-292-09693-3
1868:10.1364/AO.455464
1854:(10): 2797–2804.
1801:10.1364/AO.481805
1762:978-0-8194-5294-8
1694:thin lens formula
1669:reciprocal length
1645:physical quantity
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877:
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426:photographic lens
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147:and focal length
137:
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129:
111:
16:(Redirected from
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3690:
3680:
3679:
3558:Print permanence
3508:Cross processing
3466:CMYK color model
3451:Color management
3404:Foveon X3 sensor
3399:Three-CCD camera
3043:Miniature faking
3001:Sabattier effect
2613:Astrophotography
2468:Zebra patterning
2094:
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2080:
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2041:
2035:
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2010:
2004:
2003:
1984:(3rd ed.).
1983:
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1967:
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1933:
1918:(4th ed.).
1911:
1905:
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1821:(4th ed.).
1814:
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1787:(7): 1853–1857.
1776:
1767:
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1755:. pp. 6–9.
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1673:reciprocal metre
1567:image distortion
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1299:rectilinear lens
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1188:210 mm lens
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846:
838:
834:
832:
831:
826:
821:
817:
816:
814:
813:
812:
803:
802:
789:
769:
764:
762:
761:
749:
744:
742:
741:
729:
704:
696:
682:is given by the
681:
677:
668:
656:
639:
623:
614:
604:refractive index
597:
596:
579:
578:
572:
561:
559:
553:
540:
525:
521:
506:
505:
499:
498:
492:
491:
479:
472:
468:
391:
389:
388:
383:
376:
356:
354:
353:
348:
345:
331:
329:
328:
323:
316:
315:
307:
302:
294:
289:
281:
249:collimated light
171:of the system's
143:The focal point
132:
125:
121:
118:
112:
110:
69:
45:
37:
21:
3745:
3744:
3740:
3739:
3738:
3736:
3735:
3734:
3705:
3704:
3703:
3698:
3668:
3625:
3572:
3563:Push processing
3484:
3477:
3471:RGB color model
3420:
3326:
3210:
3122:
3088:Diagonal method
3074:
2814:
2718:Photojournalism
2581:
2413:Black-and-white
2381:
2360:Slide projector
2355:Movie projector
2234:available films
2103:
2098:
2068:
2067:
2060:
2043:
2042:
2038:
2031:
2012:
2011:
2007:
2000:
1975:
1974:
1970:
1963:
1942:
1941:
1937:
1930:
1913:
1912:
1908:
1901:
1888:
1887:
1883:
1845:
1844:
1840:
1833:
1825:. p. 168.
1816:
1815:
1808:
1778:
1777:
1770:
1763:
1746:
1745:
1734:
1729:
1706:
1685:
1681:
1680:
1621:
1609:digital cameras
1594:wide-angle lens
1551:
1545:
1541:
1535:
1531:
1525:
1521:
1515:
1508:
1497:
1491:
1488:
1482:
1440:
1420:
1410:
1409:
1404:
1398:
1395:
1389:
1385:
1375:principal plane
1367:
1341:
1332:
1303:
1302:
1290:
1287:
1284:
1260:
1257:
1252:
1251:
1249:
1248:
1240:
1229:
1209:
1202:
1201:
1200:
1199:
1191:
1190:
1189:
1186:
1178:
1177:
1176:70 mm lens
1174:
1166:
1165:
1164:50 mm lens
1162:
1154:
1153:
1152:28 mm lens
1150:
1139:
1123:
1083:
1082:
1064:
1058:
1055:
1049:
1046:sign convention
1011:
1007:
987:
978:
974:
956:
955:
923:
919:
899:
890:
886:
868:
867:
850:
847:
844:
843:
841:
840:
836:
804:
794:
790:
770:
753:
733:
727:
723:
690:
689:
679:
676:
670:
667:
661:
654:
647:
641:
637:
622:
616:
613:
607:
594:
592:
576:
574:
571:
567:
566:of the system (
560:
557:
551:
548:
539:
535:
523:
520:
514:
503:
501:
496:
494:
489:
487:
477:
475:principal plane
470:
466:
406:
362:
361:
349:
346:
343:
342:
340:
275:
274:
270:are related by
233:
218:and a narrower
133:
122:
116:
113:
70:
68:
58:
46:
35:
28:
23:
22:
15:
12:
11:
5:
3743:
3741:
3733:
3732:
3727:
3722:
3717:
3707:
3706:
3700:
3699:
3697:
3696:
3685:
3673:
3670:
3669:
3667:
3666:
3661:
3656:
3651:
3650:
3649:
3644:
3633:
3631:
3627:
3626:
3624:
3623:
3622:
3621:
3616:
3611:
3606:
3596:
3591:
3586:
3580:
3578:
3574:
3573:
3571:
3570:
3565:
3560:
3555:
3550:
3545:
3540:
3535:
3530:
3525:
3520:
3515:
3510:
3505:
3500:
3495:
3489:
3487:
3479:
3478:
3476:
3475:
3474:
3473:
3468:
3463:
3458:
3448:
3443:
3442:
3441:
3430:
3428:
3422:
3421:
3419:
3418:
3413:
3408:
3407:
3406:
3401:
3396:
3391:
3381:
3376:
3371:
3366:
3365:
3364:
3359:
3354:
3353:
3352:
3340:Digital camera
3336:
3334:
3328:
3327:
3325:
3324:
3319:
3314:
3309:
3304:
3299:
3294:
3289:
3284:
3279:
3274:
3269:
3264:
3259:
3254:
3249:
3244:
3239:
3234:
3229:
3224:
3218:
3216:
3212:
3211:
3209:
3208:
3203:
3198:
3193:
3188:
3183:
3178:
3173:
3168:
3166:Camera obscura
3163:
3158:
3153:
3148:
3143:
3138:
3132:
3130:
3124:
3123:
3121:
3120:
3115:
3110:
3108:Rule of thirds
3105:
3100:
3095:
3090:
3084:
3082:
3076:
3075:
3073:
3072:
3067:
3062:
3057:
3052:
3047:
3046:
3045:
3035:
3030:
3029:
3028:
3018:
3013:
3008:
3003:
2998:
2993:
2988:
2983:
2978:
2973:
2968:
2963:
2958:
2953:
2948:
2943:
2938:
2933:
2928:
2923:
2918:
2913:
2908:
2903:
2898:
2893:
2888:
2883:
2878:
2876:Harris shutter
2873:
2871:Hand-colouring
2868:
2863:
2858:
2853:
2848:
2843:
2838:
2833:
2828:
2822:
2820:
2816:
2815:
2813:
2812:
2807:
2802:
2797:
2792:
2787:
2782:
2777:
2772:
2767:
2762:
2757:
2756:
2755:
2745:
2740:
2735:
2730:
2725:
2720:
2715:
2710:
2705:
2700:
2695:
2690:
2685:
2680:
2675:
2670:
2665:
2660:
2655:
2650:
2645:
2640:
2635:
2630:
2625:
2620:
2615:
2610:
2605:
2600:
2595:
2589:
2587:
2583:
2582:
2580:
2579:
2574:
2569:
2564:
2559:
2557:Red-eye effect
2554:
2549:
2544:
2543:
2542:
2532:
2527:
2522:
2517:
2512:
2507:
2502:
2497:
2492:
2491:
2490:
2485:
2475:
2470:
2465:
2463:Exposure value
2460:
2455:
2450:
2448:Depth of focus
2445:
2443:Depth of field
2440:
2435:
2430:
2425:
2420:
2415:
2410:
2405:
2400:
2395:
2389:
2387:
2383:
2382:
2380:
2379:
2374:
2373:
2372:
2362:
2357:
2352:
2347:
2342:
2341:
2340:
2335:
2330:
2325:
2320:
2315:
2310:
2300:
2299:
2298:
2293:
2288:
2283:
2278:
2273:
2268:
2263:
2258:
2248:
2243:
2242:
2241:
2236:
2231:
2226:
2221:
2216:
2206:
2201:
2200:
2199:
2194:
2184:
2183:
2182:
2177:
2172:
2167:
2162:
2157:
2152:
2147:
2142:
2137:
2132:
2127:
2122:
2111:
2109:
2105:
2104:
2099:
2097:
2096:
2089:
2082:
2074:
2066:
2065:
2058:
2036:
2029:
2005:
1998:
1968:
1961:
1935:
1929:978-0805385663
1928:
1920:Addison Wesley
1906:
1899:
1881:
1848:Applied Optics
1838:
1832:978-0805385663
1831:
1823:Addison Wesley
1806:
1781:Applied Optics
1768:
1761:
1731:
1730:
1728:
1725:
1724:
1723:
1722:or focal ratio
1717:
1712:
1710:Depth of field
1705:
1702:
1620:
1617:
1598:telephoto lens
1554:52.6 mm.
1549:
1539:
1529:
1519:
1495:
1490:is decreased,
1486:
1468:
1462:
1459:
1454:
1447:
1443:
1439:
1434:
1427:
1423:
1419:
1402:
1393:
1353:
1347:
1344:
1340:
1335:
1330:
1327:
1324:
1321:
1317:
1314:
1311:
1193:
1192:
1187:
1180:
1179:
1175:
1168:
1167:
1163:
1156:
1155:
1151:
1144:
1143:
1142:
1141:
1140:
1138:
1137:In photography
1135:
1109:
1104:
1101:
1096:
1093:
1090:
1062:
1053:
1031:
1027:
1018:
1014:
1010:
1005:
1002:
999:
996:
993:
990:
984:
981:
977:
973:
970:
943:
939:
930:
926:
922:
917:
914:
911:
908:
905:
902:
896:
893:
889:
885:
882:
824:
820:
811:
807:
801:
797:
793:
788:
785:
782:
779:
776:
773:
767:
760:
756:
752:
747:
740:
736:
732:
726:
722:
719:
716:
713:
710:
707:
702:
699:
674:
665:
652:
645:
632:
620:
611:
582:
581:
569:
555:
545:
542:
537:
518:
511:
508:
484:
481:
463:
460:
437:
405:
402:
393:
392:
381:
375:
372:
369:
333:
332:
321:
313:
310:
305:
300:
297:
292:
287:
284:
232:
229:
135:
134:
76:"Focal length"
49:
47:
40:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
3742:
3731:
3728:
3726:
3723:
3721:
3718:
3716:
3713:
3712:
3710:
3695:
3686:
3684:
3675:
3674:
3671:
3665:
3662:
3660:
3657:
3655:
3652:
3648:
3645:
3643:
3640:
3639:
3638:
3635:
3634:
3632:
3628:
3620:
3617:
3615:
3612:
3610:
3607:
3605:
3602:
3601:
3600:
3599:Photographers
3597:
3595:
3592:
3590:
3587:
3585:
3582:
3581:
3579:
3575:
3569:
3566:
3564:
3561:
3559:
3556:
3554:
3551:
3549:
3546:
3544:
3541:
3539:
3536:
3534:
3531:
3529:
3526:
3524:
3521:
3519:
3516:
3514:
3511:
3509:
3506:
3504:
3501:
3499:
3496:
3494:
3493:Bleach bypass
3491:
3490:
3488:
3486:
3480:
3472:
3469:
3467:
3464:
3462:
3461:primary color
3459:
3457:
3454:
3453:
3452:
3449:
3447:
3446:Reversal film
3444:
3440:
3437:
3436:
3435:
3432:
3431:
3429:
3427:
3423:
3417:
3414:
3412:
3411:Image sharing
3409:
3405:
3402:
3400:
3397:
3395:
3392:
3390:
3387:
3386:
3385:
3382:
3380:
3377:
3375:
3372:
3370:
3367:
3363:
3360:
3358:
3355:
3351:
3348:
3347:
3346:
3343:
3342:
3341:
3338:
3337:
3335:
3333:
3329:
3323:
3320:
3318:
3315:
3313:
3312:United States
3310:
3308:
3305:
3303:
3300:
3298:
3295:
3293:
3290:
3288:
3285:
3283:
3280:
3278:
3275:
3273:
3270:
3268:
3265:
3263:
3260:
3258:
3255:
3253:
3250:
3248:
3245:
3243:
3240:
3238:
3235:
3233:
3230:
3228:
3225:
3223:
3220:
3219:
3217:
3213:
3207:
3204:
3202:
3199:
3197:
3194:
3192:
3189:
3187:
3184:
3182:
3179:
3177:
3174:
3172:
3171:Daguerreotype
3169:
3167:
3164:
3162:
3159:
3157:
3154:
3152:
3149:
3147:
3144:
3142:
3139:
3137:
3134:
3133:
3131:
3129:
3125:
3119:
3116:
3114:
3111:
3109:
3106:
3104:
3101:
3099:
3096:
3094:
3091:
3089:
3086:
3085:
3083:
3081:
3077:
3071:
3068:
3066:
3063:
3061:
3058:
3056:
3053:
3051:
3048:
3044:
3041:
3040:
3039:
3036:
3034:
3031:
3027:
3024:
3023:
3022:
3019:
3017:
3016:Stopping down
3014:
3012:
3009:
3007:
3004:
3002:
2999:
2997:
2994:
2992:
2989:
2987:
2984:
2982:
2981:Rephotography
2979:
2977:
2974:
2972:
2969:
2967:
2964:
2962:
2959:
2957:
2954:
2952:
2949:
2947:
2944:
2942:
2939:
2937:
2934:
2932:
2929:
2927:
2924:
2922:
2919:
2917:
2916:Long-exposure
2914:
2912:
2909:
2907:
2904:
2902:
2899:
2897:
2894:
2892:
2889:
2887:
2884:
2882:
2879:
2877:
2874:
2872:
2869:
2867:
2864:
2862:
2859:
2857:
2854:
2852:
2849:
2847:
2844:
2842:
2839:
2837:
2834:
2832:
2829:
2827:
2824:
2823:
2821:
2817:
2811:
2808:
2806:
2803:
2801:
2798:
2796:
2793:
2791:
2788:
2786:
2783:
2781:
2778:
2776:
2773:
2771:
2768:
2766:
2763:
2761:
2758:
2754:
2751:
2750:
2749:
2746:
2744:
2741:
2739:
2736:
2734:
2731:
2729:
2726:
2724:
2721:
2719:
2716:
2714:
2711:
2709:
2706:
2704:
2701:
2699:
2696:
2694:
2691:
2689:
2686:
2684:
2681:
2679:
2676:
2674:
2671:
2669:
2666:
2664:
2661:
2659:
2656:
2654:
2651:
2649:
2646:
2644:
2641:
2639:
2636:
2634:
2631:
2629:
2626:
2624:
2621:
2619:
2616:
2614:
2611:
2609:
2608:Architectural
2606:
2604:
2601:
2599:
2596:
2594:
2591:
2590:
2588:
2584:
2578:
2575:
2573:
2570:
2568:
2567:Shutter speed
2565:
2563:
2560:
2558:
2555:
2553:
2550:
2548:
2545:
2541:
2538:
2537:
2536:
2533:
2531:
2528:
2526:
2523:
2521:
2520:Metering mode
2518:
2516:
2513:
2511:
2508:
2506:
2503:
2501:
2498:
2496:
2493:
2489:
2486:
2484:
2481:
2480:
2479:
2476:
2474:
2471:
2469:
2466:
2464:
2461:
2459:
2456:
2454:
2451:
2449:
2446:
2444:
2441:
2439:
2436:
2434:
2433:Color balance
2431:
2429:
2426:
2424:
2421:
2419:
2416:
2414:
2411:
2409:
2406:
2404:
2401:
2399:
2398:Angle of view
2396:
2394:
2391:
2390:
2388:
2384:
2378:
2375:
2371:
2368:
2367:
2366:
2363:
2361:
2358:
2356:
2353:
2351:
2348:
2346:
2345:Manufacturers
2343:
2339:
2336:
2334:
2331:
2329:
2326:
2324:
2321:
2319:
2316:
2314:
2311:
2309:
2306:
2305:
2304:
2301:
2297:
2294:
2292:
2289:
2287:
2284:
2282:
2279:
2277:
2274:
2272:
2269:
2267:
2264:
2262:
2259:
2257:
2254:
2253:
2252:
2249:
2247:
2244:
2240:
2237:
2235:
2232:
2230:
2227:
2225:
2222:
2220:
2217:
2215:
2212:
2211:
2210:
2207:
2205:
2202:
2198:
2195:
2193:
2190:
2189:
2188:
2185:
2181:
2178:
2176:
2173:
2171:
2168:
2166:
2163:
2161:
2158:
2156:
2153:
2151:
2148:
2146:
2143:
2141:
2138:
2136:
2133:
2131:
2128:
2126:
2123:
2121:
2118:
2117:
2116:
2113:
2112:
2110:
2106:
2102:
2095:
2090:
2088:
2083:
2081:
2076:
2075:
2072:
2061:
2059:0-8194-5294-7
2055:
2051:
2047:
2040:
2037:
2032:
2026:
2022:
2018:
2017:
2009:
2006:
2001:
1995:
1991:
1987:
1982:
1981:
1972:
1969:
1964:
1958:
1954:
1949:
1948:
1939:
1936:
1931:
1925:
1921:
1917:
1910:
1907:
1902:
1896:
1892:
1885:
1882:
1877:
1873:
1869:
1865:
1861:
1857:
1853:
1849:
1842:
1839:
1834:
1828:
1824:
1820:
1813:
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1807:
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1798:
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1790:
1786:
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1773:
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1701:
1699:
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1690:
1678:
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1666:
1662:
1658:
1654:
1650:
1647:equal to the
1646:
1642:
1638:
1634:
1633:optical power
1625:
1619:Optical power
1618:
1616:
1614:
1610:
1606:
1601:
1599:
1595:
1591:
1587:
1582:
1580:
1576:
1575:angle of view
1572:
1568:
1564:
1560:
1555:
1548:
1538:
1528:
1518:
1511:
1506:
1502:
1494:
1485:
1479:
1466:
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1425:
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1417:
1407:
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1376:
1371:
1351:
1345:
1342:
1338:
1333:
1328:
1325:
1322:
1319:
1300:
1296:
1295:field of view
1283:Focal length
1281:
1273:
1255:
1246:
1238:
1233:
1227:
1223:
1219:
1215:
1206:
1197:
1184:
1172:
1160:
1148:
1136:
1134:
1132:
1127:
1120:
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1094:
1091:
1088:
1080:
1077:
1073:
1068:
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1052:
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1042:
1029:
1025:
1016:
1012:
1008:
1003:
997:
994:
991:
982:
979:
975:
971:
968:
941:
937:
928:
924:
920:
915:
909:
906:
903:
894:
891:
887:
883:
880:
864:
863:of the lens.
862:
861:optical power
853:
822:
818:
809:
805:
799:
795:
791:
786:
780:
777:
774:
765:
758:
754:
750:
745:
738:
734:
730:
724:
717:
714:
711:
705:
700:
697:
687:
685:
673:
664:
660:
651:
644:
634:
630:
626:
619:
610:
605:
589:
585:
565:
554:
546:
543:
533:
529:
517:
512:
509:
485:
482:
476:
473:to the front
464:
461:
458:
454:
450:
446:
445:magnification
442:
441:optical power
438:
435:
434:
433:
431:
427:
423:
419:
410:
403:
401:
398:
379:
373:
370:
367:
360:
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358:
352:
338:
319:
311:
308:
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298:
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273:
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271:
269:
265:
261:
256:
254:
250:
246:
242:
238:
230:
228:
225:
221:
220:angle of view
217:
216:magnification
213:
209:
204:
202:
198:
194:
190:
186:
182:
178:
174:
173:optical power
170:
166:
162:
158:
150:
146:
141:
131:
128:
120:
117:November 2021
109:
106:
102:
99:
95:
92:
88:
85:
81:
78: –
77:
73:
72:Find sources:
66:
62:
56:
55:
50:This article
48:
44:
39:
38:
33:
19:
3659:Polaroid art
3553:K-14 process
3548:Instant film
3543:Gum printing
3498:C-41 process
3483:Photographic
3384:Image sensor
3379:Film scanner
3033:Sun printing
2966:Print toning
2753:space selfie
2723:Pictorialism
2653:Ethnographic
2633:Conservation
2505:Guide number
2500:Focal length
2499:
2049:
2045:
2039:
2015:
2008:
1979:
1971:
1946:
1938:
1915:
1909:
1890:
1884:
1851:
1847:
1841:
1818:
1784:
1780:
1748:
1691:
1630:
1602:
1583:
1556:
1546:
1536:
1526:
1516:
1509:
1492:
1483:
1480:
1408:
1399:
1390:
1383:
1372:
1282:
1279:
1253:
1244:
1236:
1231:
1225:
1221:
1217:
1213:
1128:
1121:
1081:
1069:
1059:
1050:
1043:
865:
851:
688:
671:
662:
649:
642:
635:
627:
617:
608:
601:
583:
563:
549:
531:
515:
452:
449:nodal points
417:
415:
396:
394:
350:
336:
334:
267:
263:
259:
257:
253:concave lens
241:focal points
240:
234:
205:
201:point source
167:; it is the
157:focal length
156:
154:
148:
144:
123:
114:
104:
97:
90:
83:
71:
59:Please help
54:verification
51:
3664:Stereoscopy
3528:E-6 process
3523:Dye coupler
3456:color space
3369:Digiscoping
3362:camera back
3277:Philippines
3206:Visual arts
3196:Glass plate
3181:Heliography
3080:Composition
3055:Ultraviolet
3011:Stereoscopy
3006:Slow motion
2991:Scanography
2906:Kite aerial
2846:Contre-jour
2738:Post-mortem
2728:Pornography
2708:Neues Sehen
2643:Documentary
2577:Zone System
2552:Reciprocity
2478:Film format
2408:Backscatter
2386:Terminology
2256:beauty dish
2155:rangefinder
2120:light-field
2101:Photography
2021:Focal Press
1986:Focal Press
1613:crop factor
1586:normal lens
1501:normal lens
1379:focal plane
245:convex lens
208:photography
3709:Categories
3654:Lomography
3485:processing
3434:Print film
3350:comparison
3317:Uzbekistan
3267:Luxembourg
3227:Bangladesh
3176:Dufaycolor
3156:Box camera
3113:Simplicity
3070:Zoom burst
3065:Xerography
3060:Vignetting
3050:Time-lapse
3038:Tilt–shift
2931:Mordançage
2921:Luminogram
2886:Holography
2881:High-speed
2861:Fill flash
2841:Burst mode
2819:Techniques
2800:Vernacular
2795:Underwater
2790:Toy camera
2770:Still life
2698:Monochrome
2688:High-speed
2638:Cloudscape
2628:Conceptual
2530:Photograph
2515:Lens flare
2495:Film speed
2377:Zone plate
2323:wide-angle
2308:long-focus
1988:. p.
1753:SPIE Press
1727:References
1649:reciprocal
1639:or curved
1590:full-frame
1505:35 mm
1196:35 mm
224:microscopy
193:collimated
87:newspapers
3604:Norwegian
3568:Stop bath
3513:Developer
3141:Ambrotype
3103:Lead room
3026:Slit-scan
2961:Photogram
2956:Panoramic
2866:Fireworks
2851:Cyanotype
2693:Landscape
2338:telephoto
2286:reflector
2281:monolight
2276:lens hood
2261:cucoloris
2197:safelight
2108:Equipment
1665:dimension
1579:film size
1329:
1095:−
995:−
983:−
907:−
778:−
746:−
715:−
631:different
526:) to the
430:telescope
371:≈
212:telescopy
189:thin lens
177:converges
3683:Category
3389:CMOS APS
3287:Slovenia
3215:Regional
3161:Calotype
3098:Headroom
2976:Redscale
2891:Infrared
2836:Brenizer
2810:Wildlife
2733:Portrait
2678:Forensic
2668:Fine-art
2603:Aircraft
2593:Abstract
2473:F-number
2453:Exposure
2428:Clipping
2403:Aperture
2271:hot shoe
2192:enlarger
2187:Darkroom
1876:35471355
1720:f-number
1704:See also
1366:, where
640:in air (
424:(e.g. a
210:and all
206:In most
181:diverges
3694:Outline
3630:Related
3322:Vietnam
3307:Ukraine
3242:Denmark
3222:Albania
3201:Tintype
3128:History
3093:Framing
2986:Rollout
2951:Panning
2901:Kirlian
2805:Wedding
2683:Glamour
2663:Fashion
2648:Eclipse
2618:Banquet
2540:Albumen
2350:Monopod
2328:fisheye
2296:softbox
2145:pinhole
2135:instant
2125:digital
1856:Bibcode
1789:Bibcode
1715:Dioptre
1684:⁄
1659:is its
1657:dioptre
1264:
1250:
1044:In the
856:
842:
598:and EFL
530:of the
422:mirrors
397:concave
355:
341:
169:inverse
161:optical
101:scholar
3720:Length
3692:
3681:
3614:street
3609:Polish
3302:Turkey
3297:Taiwan
3282:Serbia
3272:Norway
3247:Greece
3232:Canada
2826:Afocal
2785:Street
2765:Sports
2748:Selfie
2703:Nature
2658:Erotic
2623:Candid
2598:Aerial
2586:Genres
2488:medium
2365:Tripod
2333:swivel
2246:Filter
2224:holder
2219:format
2115:Camera
2056:
2027:
1996:
1959:
1926:
1916:Optics
1897:
1891:Optics
1874:
1829:
1819:Optics
1759:
1653:metres
1641:mirror
1503:for a
1326:arctan
1122:where
1070:For a
835:where
528:vertex
416:For a
377:
337:convex
317:
159:of an
103:
96:
89:
82:
74:
3619:women
3577:Lists
3533:Fixer
3416:Pixel
3345:D-SLR
3292:Sudan
3262:Korea
3257:Japan
3252:India
3237:China
3021:Strip
2946:Night
2926:Macro
2831:Bokeh
2775:Stock
2743:Ruins
2483:large
2313:prime
2291:snoot
2251:Flash
2229:stock
2204:Drone
2165:still
2150:press
2140:phone
2130:field
1955:–66.
1663:with
1643:is a
1635:of a
1291:)
1285:(
428:or a
418:thick
197:focus
165:light
108:JSTOR
94:books
3642:film
3357:MILC
2856:ETTR
2713:Nude
2673:Fire
2572:Sync
2370:head
2318:zoom
2303:Lens
2266:gobo
2214:base
2209:Film
2180:view
2054:ISBN
2050:FG01
2025:ISBN
1994:ISBN
1957:ISBN
1924:ISBN
1895:ISBN
1872:PMID
1827:ISBN
1757:ISBN
1677:rays
1655:. A
1637:lens
1631:The
1293:and
1247:(at
1239:(at
1228:(at
1220:and
1129:See
669:and
615:and
237:lens
185:rays
155:The
80:news
3394:CCD
2175:toy
2170:TLR
2160:SLR
1864:doi
1797:doi
1667:of
1522:≈ ∞
1481:As
964:BFD
876:FFD
655:= 1
63:by
3711::
2019:.
1992:.
1990:27
1953:63
1870:.
1862:.
1852:61
1850:.
1809:^
1795:.
1785:62
1783:.
1771:^
1751:.
1735:^
1615:.
1301:,
1216:,
686::
648:=
459:).
2093:e
2086:t
2079:v
2062:.
2033:.
2002:.
1965:.
1932:.
1903:.
1878:.
1866::
1858::
1835:.
1803:.
1799::
1791::
1765:.
1686:2
1682:1
1552:=
1550:2
1547:s
1542:=
1540:1
1537:s
1532:=
1530:2
1527:s
1520:1
1517:s
1512:=
1510:f
1496:2
1493:s
1487:1
1484:s
1467:.
1461:f
1458:1
1453:=
1446:2
1442:s
1438:1
1433:+
1426:1
1422:s
1418:1
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1400:s
1394:1
1391:s
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1368:x
1352:)
1346:f
1343:2
1339:x
1334:(
1323:2
1320:=
1316:V
1313:O
1310:F
1288:f
1261:2
1258:/
1254:f
1245:K
1241:f
1237:I
1232:f
1230:2
1226:E
1222:K
1218:I
1214:E
1210:f
1124:R
1108:,
1103:2
1100:R
1092:=
1089:f
1063:2
1060:R
1054:1
1051:R
1030:.
1026:)
1017:1
1013:R
1009:n
1004:d
1001:)
998:1
992:n
989:(
980:1
976:(
972:f
969:=
942:,
938:)
929:2
925:R
921:n
916:d
913:)
910:1
904:n
901:(
895:+
892:1
888:(
884:f
881:=
852:f
848:/
845:1
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823:,
819:)
810:2
806:R
800:1
796:R
792:n
787:d
784:)
781:1
775:n
772:(
766:+
759:2
755:R
751:1
739:1
735:R
731:1
725:(
721:)
718:1
712:n
709:(
706:=
701:f
698:1
680:f
675:2
672:R
666:1
663:R
653:2
650:n
646:1
643:n
638:d
621:2
618:n
612:1
609:n
595:′
593:f
577:′
575:F
570:2
568:S
558:′
556:F
552:′
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519:F
516:s
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504:′
502:F
497:′
495:H
490:′
488:f
480:.
478:H
471:F
467:f
380:.
374:v
368:f
351:u
347:/
344:1
320:.
312:v
309:1
304:+
299:u
296:1
291:=
286:f
283:1
268:f
264:v
260:u
149:f
145:F
130:)
124:(
119:)
115:(
105:·
98:·
91:·
84:·
57:.
34:.
20:)
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