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This means a 400mm lens should be 400mm long. If you get out your ruler and measure it, you will find it is less than 400mm. That is because a camera lens really has many individual glass lenses inside, and this makes it behave as if it is longer than it really is. ... Lens Focal Length Char...
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www.paragon-press.com/lens/lenchart.htm
www.paragon-press.com/lens/lenchart.htm
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The focal length of a camera lens is the distance between the center of the lens and the film when an in-focus image is formed of an object very far away. The focal length of a camera lens is displayed on the barrel of the lens along with the measurement of the largest aperture and the maker.
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hypertextbook.com/facts/2002/MiriamJanove.shtml
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Focal length - Wikipedia, the free encyclopedia
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The focal length of an optical system is a measure of how strongly it converges (focuses) or diverges (defocuses) light. For an optical system in air, it is the distance over which initially collima...
en.wikipedia.org/wiki/Focal_length
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Focal length of the lens, which is often inscribed on the front or side of a lens in millimetres or inches (eg, f = 50 mm), is the distance to the film ... When wanting to increase that range (if the camera permits interchanging the lens), there are quite an array of lenses of different focal lengths for many modern cameras.
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www.weeno.com/art/0599/62.html
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Focal length is the distance from the film to the optical centre of the lens when the lens is focused on infinity. On most adjustable cameras it is marked in millimetres on the lens mount. On 35mm-format cameras, lenses with a focal length of 50mm are called normal or standard lenses.
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www.picture-newsletter.com/focal/index.htm
www.picture-newsletter.com/focal/index.htm
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A carrier mounting two or more different lenses of a camera can be selectively moved transverse to the optical axis of the camera so as to place any one of the lenses in operating position. The carrier can also be adjusted lengthwise of the optical axis to vary the focal length of the lenses. ... In other words:
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www.patentgenius.com/patent/4097882.html
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Security Camera Video Surveillance CCTV Systems & Security Camera Systems; ... Security Camera Lens Features: ... ; AutoIris Varifocal lens,Focal Length: 2.8-12mm, 95.6-22.1 Degrees...
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www.2mcctv.com/product_info-2MCCTV2M2812A.html
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Bright, large-diameter F1.4 25mm fixed focal length lens (35mm equivalent: 50mm) ... Focal Length f=25mm (35mm film camera equivalent 50mm) ... Overall Length 75mm / 2.95 inch (from the tip of the lens to the base side of the lens mount)
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www.panasonic.net/avc/lumix/systemcamera/dslr/lens/fixe...
www.panasonic.net/avc/lumix/systemcamera/dslr/lens/fixed_focal_length_lens.html
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Re: measuring exact focal length of camera lens Date: Fri Oct 23 10:23:34 1998; Posted By: Goulding Patrick, Undergraduate, Applied Physics, The University of Hull; Area of science: Physics; ID: 907951249.Ph...
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www.madsci.org/posts/archives/oct98/909161196.Ph.r.html
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