This link has been bookmarked by 215 people . It was first bookmarked on 08 Jan 2008, by Colton Telford.
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29 Dec 16
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smilex3md"Required Focal Length Calculator"
photography camera lenses tutorial lens reference calculator focal length focal length
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19 Jul 16
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Optical aberrations occur when points in the image do not translate back onto single points after passing through the lens — causing image blurring, reduced contrast or misalignment of colors (chromatic aberration). Lenses may also suffer from uneven, radially decreasing image brightness (vignetting) or distortion.
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Wide angle lenses have short focal lengths, while telephoto lenses have longer corresponding focal lengths.
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If one tries to fill the frame with the same subjects using both a wide angle and telephoto lens, then perspective does indeed change, because one is forced to move closer or farther from their subject. For these scenarios only, the wide angle lens exaggerates or stretches perspective, whereas the telephoto lens compresses or flattens perspective.
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Lens Focal Length* Terminology Typical Photography Less than 21 mm Extreme Wide Angle Architecture 21-35 mm Wide Angle Landscape 35-70 mm Normal Street & Documentary 70-135 mm Medium Telephoto Portraiture 135-300+ mm Telephoto Sports, Bird & Wildlife -
Telephoto lenses are more susceptible to camera shake since small hand movements become magnified, similar to the shakiness experience while trying to look through binoculars. Wide angle lenses are generally more resistant to flare, in part because the designers assume that the sun is more likely to be within the frame.
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Longer focal lengths require shorter exposure times to minimize blurring caused by shaky hands.
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one over focal length rule. This states that for a 35 mm camera, the exposure time needs to be at least as fast as one over the focal length in seconds. In other words, when using a 200 mm focal length on a 35 mm camera, the exposure time needs to be at least 1/200 seconds — otherwise blurring may be hard to avoid. See the tutorial on reducing camera shake with hand-held photos for more on this topic.
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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.
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Two Options Available with a Zoom Lens:
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Why would one intentionally restrict their options by using a prime lens?Prime lenses existed long before zoom lenses were available, and still offer many advantages over their more modern counterparts. When zoom lenses first arrived on the market, one often had to be willing to sacrifice a significant amount of optical quality. However, more recent high-end zoom lenses generally do not produce noticeably lower image quality, unless scrutinized by the trained eye (or in a very large print).
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The primary advantages of prime lenses are in cost, weight and speed. An inexpensive prime lens can generally provide as good (or better) image quality as a high-end zoom lens.
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For compact digital cameras, lenses listed with a 3X, 4X, etc. zoom designation refer to the ratio between the longest and shortest focal lengths.
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digital zoom is not the same as optical zoom, as the former only enlarges the image through interpolation
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f/# Light-Gathering Area
(Aperture Size)Required Shutter Speed Depth of Field Higher Smaller Slower Wider Lower Larger Faster Narrower -
The maximum aperture is perhaps the most important lens aperture specification, which is often listed on the box along with focal length(s).
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An f-number of X may also be displayed as 1:X (instead of f/X), as shown below for the Canon 70-200 f/2.8 lens (whose box is also shown above and lists f/2.8).
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some zoom lenses on digital SLR and compact digital cameras often list a range of maximum aperture, because this may depend on how far one has zoomed in or out. These aperture ranges therefore refer only to the range of maximum aperture, not overall range. A range of f/2.0-3.0 would mean that the maximum available aperture gradually changes from f/2.0 (fully zoomed out) to f/3.0 (at full zoom).
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Lenses typically have fewer aberrations when they perform the exposure stopped down one or two f-stops from their maximum aperture (such as using a setting of f/4.0 on a lens with a maximum aperture of f/2.0). This *may* therefore mean that if one wanted the best quality f/2.8 photograph, a f/2.0 or f/1.4 lens may yield higher quality than a lens with a maximum aperture of f/2.8.
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04 Feb 16
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16 Jan 15
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aperture range of a lens refers to the amount that the lens can open up or close down to let in more or less light
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larger aperture openings are defined to have lower f-numbers
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a smaller aperture means that objects can be in focus over a wider range of distance,
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27 Dec 14
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In the example below, the original position is shown along with two alternatives using a zoom lens. If a prime lens were used, then a change of composition would not have been possible without cropping the image (if a tighter composition were desirable)
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a larger zoom designation does not necessarily mean that the image can be magnified any more (since that zoom may just have a wider angle of view when fully zoomed out).
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11 Dec 14
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19 Nov 14
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06 Nov 14
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For compact digital cameras, lenses listed with a 3X, 4X, etc. zoom designation refer to the ratio between the longest and shortest focal lengths. Therefore, a larger zoom designation does not necessarily mean that the image can be magnified any more (since that zoom may just have a wider angle of view when fully zoomed out). Additionally, digital zoom is not the same as optical zoom, as the former only enlarges the image through interpolation. Read the fine-print to ensure you are not misled.
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13 Apr 14
akenkengood for lens distortion theory
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20 Feb 14
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the wide angle lens exaggerates or stretches perspective, whereas the telephoto lens compresses or flattens perspective
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medium and telephoto lenses generally yield better optical quality for similar price ranges
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for a 35 mm camera, the exposure time needs to be at least as fast as one over the focal length in seconds.
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For users of digital cameras with cropped sensors, one needs to convert into a 35 mm equivalent focal length.
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06 Feb 14
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16 Jan 14
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04 Oct 13
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CAMERA LENSES
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add more creative control
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focal length
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prime vs. zoom
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aperture or f-number
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The goal is to minimize aberrations, while still utilizing the fewest and least expensive elements.
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points in the image do not translate back onto single points after passing through the lens
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aberrations
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image blurring, reduced contrast or misalignment of colors (chromatic aberration)
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suffer from uneven, radially decreasing image brightness (vignetting) or distortion
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when a lens is referred to as having lower optical quality than another lens, this is manifested as some combination of the above artifacts.
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FOCAL LENGTH
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Wide angle lenses have short focal lengths
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telephoto lenses have longer corresponding focal lengths
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perspective of an image
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perspective only changes with one's location relative to their subject.
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the wide angle lens exaggerates or stretches perspective
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telephoto lens compresses or flattens perspective
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powerful compositional tool
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Perspective control
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choice in focal length
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what focal lengths are required to be considered a wide angle or telephoto lens,
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*Note: Lens focal lengths are for 35 mm equivalent cameras.
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susceptible
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Other factors may also be influenced by lens focal length
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binoculars
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Wide angle lenses are generally more resistant to flare, in part because the designers assume that the sun is more likely to be within the frame
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medium and telephoto lenses generally yield better optical quality for similar price ranges.
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FOCAL LENGTH & HANDHELD PHOTOS
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how easy it is to achieve a sharp handheld photograph.
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shorter exposure times to minimize blurring caused by shaky hands
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Longer focal lengths
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estimating how fast the exposure needs to be for a given focal length
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common rule
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one over focal length rule
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exposure time needs to be at least as fast as one over the focal length in seconds
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35 mm camera
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when using a 200 mm focal length on a 35 mm camera, the exposure time needs to be at least 1/200 second
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otherwise blurring may be hard to avoid
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this rule is just for rough guidance
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some may be able to hand hold a shot for much longer or shorter times
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ZOOM LENSES vs. PRIME LENSES
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A zoom lens is one where the photographer can vary the focal length within a pre-defined range
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cannot be changed with a "prime" or fixed focal length lens
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zoom lens
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easier to achieve a variety of compositions or perspectives
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often critical for dynamic subject matter
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photojournalism and children's photography
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using a zoom lens does not necessarily mean that one no longer has to change their position; zooms just increase flexibility
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If a prime lens were used, then a change of composition would not have been possible without cropping the image
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Prime lenses existed long before zoom lenses were available
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primary advantages of prime lenses are in cost, weight and speed
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compact digital cameras, lenses listed with a 3X, 4X, etc. zoom designation refer to the ratio between the longest and shortest focal lengths.
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INFLUENCE OF LENS APERTURE OR F-NUMBER
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the amount that the lens can open up or close down to let in more or less light
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aperture range of a lens
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Apertures
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f-numbers
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larger aperture openings are defined to have lower f-numbers
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the rest of this tutorial refers to lenses in terms of their aperture size
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larger apertures
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"faster," because for a given ISO speed, the shutter speed can be made faster for the same exposure
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smaller aperture means that objects can be in focus over a wider range of distance, a concept also termed the depth of field.
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Required Shutter Speed
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Depth of Field
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(Aperture Size)
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The maximum aperture is perhaps the most important lens aperture specification
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Portrait and indoor sports/theater photography
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very large maximum apertures
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faster shutter speed
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capable of a narrower depth of field
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The narrow depth of field in a portrait helps isolate the subject from their background.
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Manual focusing is also easier because the image in the viewfinder has a narrower depth of field
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Minimum apertures for lenses are generally nowhere near as important as maximum apertures
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11 Feb 13
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Optical aberrations occur when points in the image do not translate back onto single points after passing through the lens — causing image blurring, reduced contrast or misalignment of colors (chromatic aberration).
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28 Jan 13
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the wide angle lens exaggerates or stretches perspective, whereas the telephoto lens compresses or flattens perspective.
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13 Dec 12
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Optical aberrations occur when points in the image do not translate back onto single points after passing through the lens — causing image blurring, reduced contrast or misalignment of colors (chromatic aberration).
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08 Dec 12
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29 Nov 12
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19 Nov 12
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31 Oct 12
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06 Oct 12
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complex trade-off between cost, size, weight, lens speed and image quality
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This tutorial aims to improve understanding by providing an introductory overview of concepts relating to image quality, focal length, perspective, prime vs. zoom lenses and aperture or f-number.
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directs the path of light rays to recreate the image as accurately as possible on the digital sensor
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The goal is to minimize aberrations, while still utilizing the fewest and least expensive elements
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misalignment of colors (chromatic aberration)
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decreasing image brightness (vignetting) or distortion.
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when a lens is referred to as having lower optical quality than another lens, this is manifested as some combination of the above artifacts
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The focal length of a lens determines its angle of view
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22 Jul 12
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05 Jul 12
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05 Apr 12
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The aperture range of a lens refers to the amount that the lens can open up or close down to let in more or less light, respectively. Apertures are listed in terms of f-numbers, which quantitatively describe relative light-gathering area
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The aperture range of a lens refers to the amount that the lens can open up or close down to let in more or less light, respectively. Apertures are listed in terms of f-numbers, which quantitatively describe relative light-gathering area
-
The aperture range of a lens refers to the amount that the lens can open up or close down to let in more or less light, respectively. Apertures are listed in terms of f-numbers, which quantitatively describe relative light-gathering area
-
The aperture range of a lens refers to the amount that the lens can open up or close down to let in more or less light, respectively. Apertures are listed in terms of f-numbers, which quantitatively describe relative light-gathering area
-
The aperture range of a lens refers to the amount that the lens can open up or close down to let in more or less light, respectively. Apertures are listed in terms of f-numbers, which quantitatively describe relative light-gathering area
-
Note that larger aperture openings are defined to have lower f-numbers (often very confusing). These two terms are often mistakenly interchanged; the rest of this tutorial refers to lenses in terms of their aperture size. Lenses with larger apertures are also described as being "faster," because for a given ISO speed, the shutter speed can be made faster for the same exposure. Additionally, a smaller aperture means that objects can be in focus over a wider range of distance, a concept also termed the depth of field
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04 Apr 12
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The following table provides an overview of what focal lengths are required to be considered a wide angle or telephoto lens, in addition to their typical uses. Please note that focal lengths listed are just rough ranges, and actual uses may vary considerably; many use telephoto lenses in distant landscapes to compress perspective, for example.
Lens Focal Length* Terminology Typical Photography Less than 21 mm Extreme Wide Angle Architecture 21-35 mm Wide Angle Landscape 35-70 mm Normal Street & Documentary 70-135 mm Medium Telephoto Portraiture 135-300+ mm Telephoto Sports, Bird & Wildlife -
A common rule of thumb for estimating how fast the exposure needs to be for a given focal length is the one over focal length rule. This states that for a 35 mm camera, the exposure time needs to be at least as fast as one over the focal length in seconds. In other words, when using a 200 mm focal length on a 35 mm camera, the exposure time needs to be at least 1/200 seconds — otherwise blurring may be hard to avoid. See the tutorial on reducing camera shake with hand-held photos for more on this topic.
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Note that larger aperture openings are defined to have lower f-numbers (often very confusing).
-
Lenses with larger apertures are also described as being "faster," because for a given ISO speed, the shutter speed can be made faster for the same exposure.
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06 Dec 11
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30 Nov 11
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Lens Focal Length* Terminology Typical Photography Less than 21 mm Extreme Wide Angle Architecture 21-35 mm Wide Angle Landscape 35-70 mm Normal Street & Documentary 70-135 mm Medium Telephoto Portraiture 135-300+ mm Telephoto Sports, Bird & Wildlife -
Longer focal lengths require shorter exposure times to minimize blurring caused by shaky hands.
-
A common rule of thumb for estimating how fast the exposure needs to be for a given focal length is the one over focal length rule.
-
one often had to be willing to sacrifice a significant amount of optical quality.
-
However, more recent high-end zoom lenses generally do not produce noticeably lower image quality, unless scrutinized by the trained eye (or in a very large print).
-
The primary advantages of prime lenses are in cost, weight and speed. An inexpensive prime lens can generally provide as good (or better) image quality as a high-end zoom lens.
-
best prime lenses almost always offer better light-gathering ability (larger maximum aperture) than the fastest zoom lenses — often critical for low-light sports/theater photography, and when a shallow depth of field is necessary.
-
The aperture range of a lens refers to the amount that the lens can open up or close down to let in more or less light, respectively. Apertures are listed in terms of f-numbers, which quantitatively describe relative light-gathering area (depicted below).
-
Note that larger aperture openings are defined to have lower f-numbers (often very confusing).
-
depth of field
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18 Nov 11
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08 Oct 11
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24 Sep 11
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Keep in mind that using a zoom lens does not necessarily mean that one no longer has to change their position; zooms just increase flexibility.
-
3X, 4X, etc. zoom designation refer to the ratio between the longest and shortest focal lengths. Therefore, a larger zoom designation does not necessarily mean that the image can be magnified any more
-
Note that larger aperture openings are defined to have lower f-numbers
-
A range of f/2.0-3.0 would mean that the maximum available aperture gradually changes from f/2.0 (fully zoomed out) to f/3.0 (at full zoom).
-
-
09 Sep 11
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A zoom lens is one where the photographer can vary the focal length within a pre-defined range
-
The primary advantage of a zoom lens is that it is easier to achieve a variety of compositions or perspectives
-
This advantage is often critical for dynamic subject matter
-
An inexpensive prime lens can generally provide as good (or better) image quality as a high-end zoom lens.
-
Finally, the best prime lenses almost always offer better light-gathering ability (larger maximum aperture) than the fastest zoom lense
-
often critical for low-light sports/theater photography, and when a shallow depth of field is necessary
-
The aperture range of a lens refers to the amount that the lens can open up or close down to let in more or less light, respectively. Apertures are listed in terms of f-numbers, which quantitatively describe relative light-gathering area
-
(depicted below).

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05 Sep 11
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Linda C"This tutorial aims to improve understanding by providing an introductory overview of concepts relating to image quality, focal length, perspective, prime vs. zoom lenses and aperture or f-number."
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26 Apr 10
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13 Apr 10
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14 Mar 10
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10 Feb 10
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13 Jan 10
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11 Nov 09
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13 Oct 09
Ex3 oP"Understanding camera lenses can help add more creative control to digital photography. Choosing the right lens for the task can become a complex trade-off between cost, size, weight, lens speed and image quality. This tutorial aims to improve understanding by providing an introductory overview of concepts relating to image quality, focal length, perspective, prime vs. zoom lenses and aperture or f-number."
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12 Sep 09
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02 Sep 09
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20 Mar 09
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27 Feb 09
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26 Jan 09
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03 Nov 08
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03 Oct 08
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01 Oct 08
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12 Sep 08
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03 Aug 08
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23 Jul 08
Guhanath RajendranUnderstanding Camera Lenses
web learn lessons resource photo Online tutorial Links photography
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Understanding Camera Lenses
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Understanding Camera Lenses
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19 Feb 08
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08 Jan 08
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07 Jan 08

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