- Base curve radius
No footnotes date June 2010 Base curve radius or simply base curve , abbreviated BCR or BC , is the measure of one important parameter of a Corrective lens lens in optometry . On a spectacle lens , it is the flatter curvature of the front surface and on a contact lens it is the curvature of the back surface. Typical values for a contact lens are from 8.0 to 10.0 mm. The base curve is the radius of the sphere of the back of the lens that the prescription describes. Contact lenses must fit well to the wearer s cornea in order to be comfortable and to facilitate tears tear exchange and oxygen transmission. In everyday practice, if lenses feel loose and slide easily a smaller base curve may work better. A large base curve may be needed if they feel tight. Lenses with smaller base curves are referred to as steep . See also Corrective lenses Lens shape Lens shape Radius of curvature optics External links http www.opticampus.com cecourse.php?url lens design base OptiCampus.com http www.allaboutvision.com contacts contact lens rx.htm Understanding contact lens prescriptions http www.eyetopics.com articles 112 1 Contact Lens Prescriptions Explained Contact Lens Prescriptions Explained detailed article about contact lens prescriptions http www.korean lens.com what lens base curve and it most important information know buying circle lens 68.html How to choose circle lenses Category Contact lenses ... more details
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- Minolta AF 50mm f/1.4 lens
Infobox photographic lenses name Minolta AF 50mm f 1.4 lens image caption maker Minolta , Sony feat is feat usm feat sbf feat macro feat special application Normal wide aperture prime type Prime flength 50mm fov 47 aperture f 1.4 f 22 groups 6 elements 7 diaphragm 7 circular close dist 450 mm max mag 1 6.66 max diameter 65 mm max length 43 mm weight 220 g filter 55 mm hood bayonet, circular av horiz av vert av diag start 2006 Sony stop replace Minolta versions 1985 and the 1990 RS restyled succeeded by Sony version in 2006 msrp US 350 category Minolta lenses Originally produced by Minolta , and currently produced by Sony , the 50mm f 1.4 is a normal lens normal wide aperture prime photographic lens compatible with cameras using the Minolta AF and Sony lens mount s. Sources http www.dyxum.com lenses detail.asp?IDLens 305 Dyxum lens data and http www.dyxum.com reviews lenses reviews.asp?IDLens 305 reviews External links http www.sony.co.uk view ShowProduct.action?product SAL 50F14&site odw en GB&pageType Overview&category DDL Standard Lenses Sony SAL 50F14 50mm F1.4 Fixed lens Category Minolta lenses Category Sony Alpha DSLR cameras photo stub ru Minolta AF 50mm f 1.4 ... more details
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- Varifocal lens
about varifocal camera lenses corrective eyeglass lenses Progressive lens A varifocal lens is a camera lens with variable focal length in which Focus optics focus changes as focal length and magnification changes, as compared to parfocal lens parfocal true zoom lens , which remains in focus as the lens zooms focal length and magnification change . Many so called zoom lenses, particularly in the case of fixed lens cameras, are actually varifocal lenses . ref cite web url http www.rogercavanagh.com helpinfo 30 parfocal.stm title Parfocal Lenses accessdate 2007 11 18 last Cavanagh first Roger date 2003 05 29 archiveurl http web.archive.org web 20071007070643 http www.rogercavanagh.com helpinfo 30 parfocal.stm Bot retrieved archive archivedate 2007 10 07 ref Image Varifocal example.jpg thumb 500px none A varifocal lens. Left image is at 2.8mm, in focus. Middle image is at 12mm with the focus left alone from 2.8mm. Right image is at 12mm refocused. The close knob is focal length and the far knob is focus. References Footnotes reflist Notations cite web url http www.tokina usa.com glossary.html title Lens Glossary accessdate 2007 11 18 work Tokina Industrial, Inc. optics stub Category Photographic lenses es Varifocal ja pt Lente varifocal ... more details
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- Sigma 10?20mm f/4?5.6 EX DC HSM lens
Infobox photographic lenses name 10 20mm F4 5.6 EX DC HSM image Sigma 10 20mm f4 5.6 EX DC HSM lens hood.jpg maker Sigma Corporation Sigma feat is n feat usm y feat sbf feat macro n feat special type z application Consumer Super Wide Angle Zoom for Digital SLRs flength 10 20mm fov 102.4° 63.8° aperture f 4 f 5.6 groups 10 elements 14 diaphragm 6 close dist 24cm 9.4in max mag 1 6.7 weight 465g 16.4oz max diameter 83.5mm max length 81mm filter 77mm hood y av horiz av vert av diag start msrp 730 USD category Sigma lenses The Sigma 10 20mm lens is an enthusiast level, Ultra wide angle lens ultra wide angle rectilinear lens rectilinear zoom lens made by Sigma Corporation specifically for use with small format digital SLR s. ref cite web author Sigma Corporation title 10 20mm f 4 5.6 EX DC HSM url http www.sigmaphoto.com lenses lenses all details.asp?id 3301&navigator 6 year 2007 quote accessdate 2008 07 02 ref broken link See also List of Nikon compatible lenses with integrated autofocus motor References references photo stub Sigma lenses zh 10 20mm ... more details
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- Leica R bayonet
and film is 47 mm. The modern apochromatic manual focus Leica R lenses are especially notable for their world ... of its R Series manual focus SLR and lenses. Variants 1 cam 1 cam lenses have a sloped cam ... ROM contacts. 1 cam lenses may be modified to work fully on later cameras. 2 cam 2 cam lenses have ... mode. As with 1 cam lenses, Leica does not recommend that they be used on the R8 R9 although they can be modified as with 1 cam lenses. 3 cam 3 cam lenses have a third stepped R Cam fitted that communicates ... all three mechanical connections. R only These lenses only have the stepped R cam and only ... have the stepped R cam plus electrical contacts allowing the lenses to communicate additional information ... the lenses are fully compatible with earlier R cameras. The additional information is used in flash ... other systems lenses can be adapted to fit on a Leica R and retain infinity focus, but R lenses can ... R bayonet mount to take R lenses Citation needed date April 2011 . A number of manufacturers have produced adapters to allow Canon EOS cameras to take R lenses, these operate only in stop down ... more details
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- Nikon S-mount
S , Nikon S2 , Nikon SP , Nikon S3 , Nikon S4 . The lenses were sold under the name Nikkor . The mount ... mean that although Carl Zeiss AG Zeiss wide angle lenses can be used on the Nikon cameras and vice versa, the longer lenses 50 mm and above , if used, will not be able to focus at both close range ... length lenses specifically designed to focus properly when mounted on a Contax. These were the 85mm, 105mm, and 135mm lenses. Each was marked with a C on the side of the lens barrel. This is not to be confused ... that the lenses were Optical coating coated . The mount itself has two bayonets, one inside the camera and another outside. Lenses that use the bayonet inside the camera need have no focusing ... only. Focusing of such lenses could be done by rotating the toothed wheel on the top front of the camera ... bayonet is used to mount longer and heavier lenses where the built in helicoid would not be strong enough to rotate the lens barrel. Such lenses are focused using a focusing ring and distance scale on the lens just like typical SLR lenses the distance scale on the camera body will be covered by the lens flange and thus not visible . Nikon produced a very large range of Nikkor lenses for these cameras ... including Fuji now Fujifilm , Komura photography Komura and Zunow made S mount lenses at the time ... Bessa R2S as well as several lenses for the Nikon S mount. Further reading Rotoloni, Robert, Nikon ... cameras and Nikkor Voigtlander lenses in S mount. Category Lens mounts Category Photographic lenses Category Nikon S Category Rangefinder cameras Category 135 film cameras ... more details
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- Vision Rx Lab
used in the production of ophthalmic lenses. Most new progressive lenses are machined using this technique ... Lenses Polycarbonate was developed in the 1970s for aerospace applications, and is used for the helmet visors of astronauts and for space shuttle windshields. Eyeglass lenses made of polycarbonate were introduced in the early 1980s in response to a demand for lightweight, impact resistant lenses. Since then, polycarbonate lenses have become the standard for safety glasses, sports goggles and children s eyewear. Because they are less likely to fracture than regular plastic lenses, polycarbonate lenses also are a good choice for rimless eyewear designs where the lenses are attached to the frame components with drill mountings. Trivex Lenses Despite its many advantages, polycarbonate isn t the only ... Pittsburgh, Penn. introduced a rival lens material called Trivex. Like polycarbonate lenses, lenses ... lenses.Trivex lenses, however, are composed of a urethane based monomer and are made from a cast molding process similar to how regular plastic lenses are made. This gives Trivex lenses the advantage of crisper optics than injection molded polycarbonate lenses, according to PPG. References Reflist ... site http www.youtube.com visionrxlab Vision Rx Lab YouTube Channel Category Lenses ... more details
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- List of lens designs
Technology related lists Lens designs Category Lenses List optics stub ... more details
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- Circle contact lens
File Circle contact lens.jpg right thumb A girl wearing circle contact lenses. A circle contact lens ... Circle contact lenses make one s eyes appear larger and come in a variety of colors and effects. They are a new ... contact lenses that are sold in the United States are on average 14mm 16mm, similar to the diameter of the cosmetic circle contact lenses citation needed date October 2011 . The difference between the two types of lenses is that circle contact lenses are tinted not only in areas that cover ... zone in the middle is transparent and it is large enough to provide clear vision. The lenses ... life style fashion lady gagastyle contact lenses put your health at risk 2021897.html title Lady Gaga style Contact Lenses Put Your Health At Risk publisher The Independent date 2010 07 08 accessdate 2010 07 17 location London ref Many people consider circle lenses to be a fashion accessory ... circle contact lenses can be bought in some stores. They can be purchased without a Eyeglass prescription ... ref Risks Many issues concerning the quality of these lenses have arisen when date October 2011 . Currently when date October 2011 there are still companies selling circle contact lenses without the approval of health services. Many circle lenses are manufactured in Asian countries where there are no guidelines or supervision over the production of the lenses. ref name CBS news The popularity of the lenses ... lifestyle beauty girls go gaga over big eyes but the fashion lenses may not be safe 20100709 1041f.html?autostart 1 title Girls Go Gaga Over Big Eyes, but the Fashion Lenses May Not Be Safe ... 3, 2010. Accessed July 4, 2010. ref noted that circle lenses were being worn around the country and were ... Lenses and the LAW url http www.mycandyeyes.com work Legality ref Legality United States In the United States decorative, non corrective contact lenses are considered medical devices by the Food ... Lenses publisher U.S. Food and Drug Administration date 2006 11 24 accessdate 2012 01 11 ref Additionally ... more details
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- Progressive lens
spectacle lenses , also called progressive addition lenses PAL , progressive power lenses , graduated prescription lenses , and varifocal or multifocal lenses , are corrective lens es used in glasses ... powered lenses the Minkwitz theorem Sheedy JE, Campbell C, Optom Vis Sci. 2005 Oct 82 10 916 22 ... ref Bennett A. 1973 Variable and Progressive power lenses. Manufacturing Optics Int ... later became part of Essilor in 1959. Early progressive lenses were relatively crude designs but modern sophisticated progressive lenses have gained greater patient acceptance and include special designs to cater to many separate types of wearer application for example progressive addition lenses may .... Progressive addition lenses avoid the discontinuities image jumps in the visual field created by the majority of Bifocals bifocal and trifocal lenses and are more cosmetically attractive. Since Bifocals ... on the lens surface of a progressive lens appears more youthful since the single vision lenses associated with younger wearers are free of segments or lines on the surface. Progressive lenses ... Progressive lenses suffer the disadvantage of the power progression creating regions of Aberration ... resolution blur , which varies in relation to the quality of the lens. As the lenses combine a range ... it is best to start wearing progressive lenses early in the development of presbyopia around ... vision, there is an inherent impact on peripheral vision with progressive lenses which is more obvious than that which is found in single vision lenses. This can affect the intermediate portion of the vision ... reading lens. File ClearVisionArea.jpg Fitting Progressive lenses require careful placement ... head position in order to see clearly. Cost Progressive lenses are generally dispensed at a higher ... lenses have different glazing restrictions, lens material availabilities, maximum and minimum ... end varifocal lenses is considerable. ref Progressive addition lenses measurements and ratings. Sheedy ... more details
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- Vario-Sonnar
The Vario Sonnar is a Carl Zeiss AG Carl Zeiss photographic lens design named in relation to the Zeiss Sonnar . This lens type has an infinitely variable focal length which can replace a whole series of lenses for a certain picture format. External links http www.pbase.com kkawakami image 61106437 Vario Sonnar diagram Category Zeiss lenses Photography stub ja ... more details
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- Gliding Mirror
The gliding Single lens reflex camera mirror is Hasselblad Hasselblad s solution to the problems experienced when using telephoto lenses on select 500 and 200 series SLR cameras. The mirror is able to glide backwards about 8mm before folding upwards, which allows it to clear the rear element of certain telephoto lenses while still providing 100 viewfinder coverage. Category Photography equipment photo stub ... more details
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- Field lens
In imaging optics, a field lens is a positive powered lens or group of lenses that comes after the objective lens and before the image plane or the eyepiece , serving to change the size of the image, ref http www.colorado.edu physics phys1230 phys1230 fa01 topic43.html Judah Levine, University of Colorado Physics 1230 Light and Color The Field Lens. Fall 2001 ref ref http spie.org x34410.xml SPIE Optopedia Field Lens ref or to provide image space telecentricity . References Reflist optics stub Category Lenses Category Microscope components de Feldlinse ... more details
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- Simple lens
Unreferenced stub auto yes date December 2009 In optics , a simple lens or singlet lens is a lens optics lens consisting of a single simple element. Typical examples include a magnifying glass or a lens in a pair of simple glasses reading glasses . Simple lenses are prone to aberration in optical systems aberrations , especially chromatic aberration . They cannot be used for precise imaging and make poor camera lens es. They are commonly used for laser applications, however, where the beams are both monochromatic minimizing chromatic aberration and narrow minimizing spherical aberration . Some camera s with Focus free lens fixed lenses have been made using a simple lens, usually a meniscus lens with the convex face facing outward. In such examples the lens aperture is made small and in some cases such as the Kodak Brownie camera Brownie 127 camera , the photographic film film plane is curved to reduce the impact of aberrations. See also Lens optics Doublet lens Aspheric lens DEFAULTSORT Simple Lens Category Photographic lenses Category Lenses Optics stub zh ... more details
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- Canon EF
Canon EF can refer to a specific product or a product line Canon EF camera A manual focus 135 film 35mm Single lens reflex camera SLR Canon EF lens mount A line of electro focus Photographic lens lenses disambig ... more details
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- Rayner
Rayner IPA en re n r may refer to Rayner company , a manufacturer of intraocular lenses and surgical equipment Rayner surname , people with the surname Rayner people with the firstname Rayner disambig de Rayner pt Rayner ... more details
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- Polyhydroxyethylmethacrylate
Image Polyhydroxyethylmethacrylate structural.svg thumb right structure of pHEMA Poly 2 hydroxyethyl methacrylate pHEMA is a polymer that forms a hydrogel in water. It was invented by Drahoslav Lim for use in soft contact lenses. Copolymers of pHEMA are still widely used today. pHEMA functions as a hydrogel by rotating around its central carbon. In air, the non polar methyl side turns outward, making the material brittle and easy to grind into the correct lens shape. In water, the polar hydroxyethyl side turns outward and the material becomes flexible. Pure pHEMA yields lenses that are too thick for sufficient oxygen to diffuse through, so all contact lenses that are pHEMA based are manufactured with copolymers that make the gel thinner and increase its water of hydration . ref name Biomaterials cite book last Ratner first Buddy D. title Biomaterials Science, An Introduction to Materials in Medicine publisher Elsevier Academic Press year 2004 isbn 0 12 582463 7 ref These copolymer hydrogel lenses are often suffixed filcon , such as Methafilcon , which is a copolymer of hydroxyethyl methacrylate and methyl methacrylate . References references Category Plastics ... more details
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- B&L
B&L is an abbreviation that may mean Boston and Lowell Railroad , a railroad line of the MBTA Commuter Rail system in Massachusetts, United States Bausch & Lomb , an American company specializing in optical applications, including corrective lenses disambig Category abbreviations ... more details
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- Hydron
Hydron has the following meanings Hydron chemistry , a positive hydrogen cation Hydron He Man , a character in the He Man universe Hydron medicine , a Chinese brand of eye drops for lenses disambig sr Hidron ... more details
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- Celor lens
Unreferenced date August 2009 A Celor lens is a highly corrected photographic lens lens of the Dialyt lens Dialyt type, designed for process photography , involving reproduction at or near 1 1 scale. DEFAULTSORT Celor Lens Category Photographic lenses optics stub ... more details
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- List of soft contact lens materials
unreferenced date February 2012 Alphafilcon A Asmofilcon A Balafilcon A Comfilcon A Enfilcon A Etafilcon A Galyfilcon A Hilafilcon A Hilafilcon B Hioxifilcon A Hioxifilcon D Lotrafilcon B Methafilcon A Omafilcon A Phemfilcon A Polymacon Senofilcon A Tetrafilcon A Vifilcon A POLY HEMA Category Contact lenses ... more details
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- Norman G. Gaylord
Dr. Norman G. Gaylord 1923 2007 was an American industrial chemist notable for a major improvement to contact lenses he developed a new rigid material, siloxane methacrylate whose permeable qualities made it applicable to the production of contact lenses. ref name NYT http www.nytimes.com 2007 09 21 us 21gaylord.html New York Times Norman Gaylord, a Chemist, Is Dead at 84 September 21, 2007 Norman G. Gaylord, a versatile industrial chemist who helped develop a safe and permeable material for hard contact lenses ref ref name ACS http www.polyacs.org 143.html American Chemical Society Division of Polymer Chemistry Dr. Norman G. Gaylord, d. 2007 ref For his contribution to the production of lenses Gaylord received in 1985 Founder s Award from the American Academy of Optometry . ref name NYT References reflist Persondata NAME ALTERNATIVE NAMES SHORT DESCRIPTION DATE OF BIRTH 1923 PLACE OF BIRTH DATE OF DEATH 2007 PLACE OF DEATH Category American inventors Category American chemists Category 2007 deaths Category 1923 births ... more details
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- Hektor (lens)
Orphan date February 2009 Unreferenced date November 2006 The Hektor is a photographic lens design manufactured by Leica Camera . The first lens speed fast lens available for the Leica I A was the Hektor 50mm f 2,5. Later, the design was adapted for use as a long portrait lens, available first in a 135mm F number f 4,5 screw mount version and later in a 125mm f 2,5 bayonet mount version. It is reported that Max Berek , who designed the original lens line for Leitz , named the Hektor after his dog. Fact date February 2007 Lenses named Hektor have also been used by Leitz as projection lenses for their Prado line of slide projectors, e.g. the Hektor 2.5 85 or the Hektor 2.5 100. Category Photographic lenses ... more details
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- Canon EF 70-210mm lens
Unreferenced stub auto yes date December 2009 File Canon 70 210mm f4 7303.jpg thumb 200px Canon 70 210mm f 4 The EF 70 210mm lens is a discontinued telephoto lens telephoto zoom lens zoom photographic lens lens made by Canon Inc. The lens has an Canon EF lens mount EF mount and works with Canon EOS EOS film and digital cameras. The lens comes in two different versions Canon EF 70 210mm F 4 AFD 1987 1990 Canon EF 70 210mm F 3.5 4.5 USM introduced 1990 The lens was superseded by the Canon EF 80 200mm lens 80 200mm lens and the Canon EF 70 200mm lens 70 200mm lenses . Canon EF lenses DEFAULTSORT Canon Ef 70 210mm Lens Category Canon EF lenses Photo stub ... more details
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- Minolta AF 300mm f/2.8 G SSM lens
Originally produced by Minolta , and currently produced by Sony , the 300mm f 2.8 G SSM is a professional telephoto lens telephoto prime photographic lens compatible with cameras using the Minolta AF and Sony lens mount s. Sources http www.dyxum.com lenses detail.asp?IDLens 309 Dyxum lens data External links http www.sony.co.uk view ShowProduct.action?product SAL 300F28G&site odw en GB&pageType Overview&category DDL Telephoto Lenses Sony SAL 300F28G 300mm F2.8 G Category Minolta lenses Category Sony Alpha DSLR cameras photo stub ru Minolta AF 300mm f 2.8 ... more details
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