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The photographer often moves to keep the same image size on the film for a particular object. Observe in the comparison images below that although the foreground object remains the same size, the background changes size; thus, perspective is dependent on the distance between the photographer and the
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and the other with a long-focus lens, will show identical perspective, in that near and far objects appear the same relative size to each other. Comparing magnification by using a long lens to magnification by moving closer, however, the long-focus-lens shot appears to compress the distance between
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lens, 50 mm focal length for 35 mm film format, is conventionally regarded as a "correct" perspective, though a longer lens is usually preferred for a more pleasing perspective for portraits.
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exhibited by shorter focal length lenses where (when the photographer stands closer to the given subject) different portions of a subject in a photograph can appear out of proportion to each other.
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is the same; photographers will sometimes use this effect to defocus the background in an image to "separate" it from the subject. This background blurring is often referred to as
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around the field edges. Telescopes are normally intended for visual use, so they are not corrected to produce a large flat field like dedicated camera lenses and tend to show
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subject. The longer focus lenses compress the perception of depth, and the shorter focus exaggerate it. This effect is also used for
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that is longer than the diagonal measure of the film or sensor that receives its image. It is used to make distant objects appear
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objects due to the perspective from the more distant location. Long lenses thus give a photographer an alternative to the type of
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with magnification increasing as longer focal length lenses are used. A long-focus lens is one of three basic
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value written on the lens, for example: a 500 mm lens. The most common type of long-focus lens is the
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From the invention of photography in the 19th century, images have been captured using standard
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is a function solely of viewing location. Two images taken from the same location, one with a
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To use a telescope as a camera lens requires an adapter for the standard 1.25 inch tube
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102:. This effect is similar to moving closer to the object, but is not the same, since
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adapted as early portrait lenses. Besides being used in an astronomical role in
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Effect of different focal lengths on photographs taken from the same place:
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Long lenses also make it easier to blur the background more, even when the
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Designing a
Photograph: Visual Techniques for Making Your Photographs Work
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Applied photographic optics: lenses and optical systems for photography
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to make the physical length of the lens shorter than the focal length.
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Long-focus lenses are best known for making distant objects appear
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types classified by relative focal length, the other two being a
446:(2nd ed.). Delmar Thomson (Cengage) Learning. p. 71.
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Since the late 1990s compact digital cameras have been used in
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adjustment. The 1.25 inch mount is smaller than many film and
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Rudolf
Kingslake, A history of the photographic lens, page 33
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The manual of photography: photographic and digital imaging
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adapter, which in turn attaches to an adapter for the
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A 500 mm long-focus lens of non-telephoto design
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by photographers. Long lenses are often used with a
78:, which incorporate a special lens group known as a
318:since telescopes almost always lack diaphragms for
275:, telescopes are adapted as long-focus lenses in
473:(2nd ed.). Ayer Publishing. p. 537.
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94:Sports photographers using long-focus lenses
533:"Long-focus microscope with camera adapter"
392:(3rd ed.). Focal Press. p. 294.
419:(9th ed.). Focal Press. p. 93.
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470:Cassell's cyclopaedia of photography
191:The above photos were taken using a
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27:Camera lens with big focal length
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259:Telescopes as long-focus lenses
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547:"Astrophotography techniques"
500:. Amphoto Books. p. 14.
467:Bernard Edward Jones (1911).
287:and long-focus microscopy.
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367:Photographic lens design
413:R. E. Jacobson (2000).
386:Sidney F. Ray (2002).
113:perspective distortion
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440:Bruce Warren (2001).
326:so they tend to show
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267:including telescope
203:Constant object size
567:Photographic lenses
494:Bill Smith (2001).
362:Secret photography
339:afocal photography
332:optical aberration
277:nature photography
265:optical telescopes
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480:978-0-405-04922-4
453:978-0-7668-1777-7
426:978-0-240-51574-8
399:978-0-240-51540-3
294:mount, usually a
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60:photographic lens
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52:focal length
50:which has a
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443:Photography
357:Film format
344:digiscoping
253:135 mm
210:dolly zooms
186:210 mm
104:perspective
64:normal lens
48:camera lens
40:photography
373:References
328:vignetting
304:lens mount
269:objectives
241:50 mm
229:28 mm
174:70 mm
162:50 mm
150:28 mm
72:millimeter
100:magnified
56:magnified
561:Category
351:See also
320:aperture
292:eyepiece
316:filters
296:T-mount
86:Effects
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214:normal
128:tripod
66:and a
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193:35 mm
124:bokeh
46:is a
502:ISBN
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448:ISBN
421:ISBN
394:ISBN
312:gain
42:, a
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38:In
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