Lens (optics) - Wikipedia, the free encyclopedia
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A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens is a lens consisting of a single optical el...
en.wikipedia.org/wiki/Lens_(optics)
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To calculate the focal length needed: Formula:; ... Example:; What focal length is needed for an object be 20ft high at a distance of 200 feet using a 2/3" camera?; (Note: Formula will work using feet or meters for the variables);
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www.isorainbow.com/tech/formula.html
www.isorainbow.com/tech/formula.html
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This page is useful to calculate the required lens focal length to take a picture of an object of size yo at a distance xo in order to generate an image of size yi on the film (or the CCD/C-MOS imager). The film plane is located at a distance xi.
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www.giangrandi.ch/optics/lenses/focalcalc.html
www.giangrandi.ch/optics/lenses/focalcalc.html
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The formula for focal length is: ... = lens focal length in millimeters ... In order to keep the image within the imaging surface on both cameras, different focal length lenses must be used. By applying the correct camera scale factor for each camera (based on the imaging surface size), the correct lens focal length can...
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www.adept.com/main/ke/Data/V%20Plus/AdeptVision%20User/...
www.adept.com/main/ke/Data/V%20Plus/AdeptVision%20User/Lens_Select.focal.length.html
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This page has a CALCULATOR below to help you determine the focal length of the lens you need to order from us to fill up most of your CCD (or other image sensor types). We assume a C mount lens... ... Applying The Lens Formula:
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www.compumodules.com/image-processing/focal-length-calc...
www.compumodules.com/image-processing/focal-length-calculator.shtml
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In other words, focal length equals image distance for a far subject. To focus on something closer than infinity, the lens is moved farther away from the film. This is why most lenses get longer when you turn the focusing ring. ... The distances follow this formula:
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www.paragon-press.com/lens/lenchart.htm
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Module 5: Focal length of a lens ... Then the lens that adds minus vergence is a minus lens, the focal length is negative, and the power is 1 divided by the negative focal length in meters, so the power of this lens is negative.
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www.nfos.org/degree/opt11/module_05c.html
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Module 5: Focal length of a lens ... "What point on the lens do you measure from to get the focal length? Is it the same distance as the other focal length, the one that you would get from the primary focal point? Do you measure them from the same point?"
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www.nfos.org/degree/opt11/module_05b.html
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The principal focal length of a lens is determined by the index of refraction of the glass, the radii of curvature of the surfaces, and the medium in which the lens resides. It can be calculated from the lens-maker's formula for thin lenses.
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hyperphysics.phy-astr.gsu.edu/hbase/geoopt/foclen.html
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