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Topic: Aspherical lens

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	Aspherical Lenses
		Spherical aberration of a spherical lens and convergence of parallel light rays with the use of a aspherical lens element.
		The OP-Fisheye Nikkor 10mm f5.6 is one of the earliest in Nikkor family to use an aspherical lens front element to ensure its mathematically correct illumination pattern.
		Sometimes, the light passing through the central area of a lens cannot be focused at precisely the same plane as the light passing through the peripheral areas.
	www.mir.com.my /rb/photography/opinion/html/aspherical.htm (1135 words)

	Photographic lens - Wikipedia, the free encyclopedia
		The lens may usually be focused by adjusting the distance from the lens assembly to the image-forming surface, or by moving elements within the lens assembly.
		The maximum usable aperture of a lens is usually specified, as the focal ratio or f-number, the focal length divided by the actual aperture in the same units.
		An extreme wideangle lens of large aperture must be of very complex construction to correct for optical aberrations, which are worse at the edge of the field and when the edge of a large lens is used for image-forming.
	en.wikipedia.org /wiki/Photographic_lens (1263 words)

	Glossary
		Since the refraction of an air lens is opposite that of a glass lens, a convex shape acts as a concave lens and a concave shape acts as a convex lens.
		The aperture of a lens is related to the diameter of the group of light rays passing through lens and determines the brightness of the subject image formed on the focal plane.
		A special lens element with a surface curved with the ideal shape to correct these aberrations, i.e., a lens having a free-curved surface which is not spherical, is called an aspherical lens.
	opd.usa.canon.com /html/eflenses/lens101/glossary/index_a.html (2578 words)

	Aspherical Lenses from HOYA OPTICS: Leading supplier of advanced optical materials & components
		HOYA is the only manufacturer to own both large scale glass manufacturing and lens molding.
		HOYA has a team of glass material, lens design and optical system experts available to assist you with your requirement, whether you are looking for a lens upgrade or new system design.
		Our lens quality is backed by an optical quality assurance system and ISO9000 certification.
	www.hoyaoptics.com /aspherical_lenses/index.htm (184 words)

	Lens - SIGMA CORPORATION
		The aspherical lens complex allows freedom of design, improved performance, a reduced number of component lenses and a compact size.
		This lens is equipped with a system that moves the rear lens group for highspeed, silent focusing.
		The super wide angle lens having a large front-lens uses a rear focusing system to move the rear-lens apparatus and enhance the floating effect, and the18-125 mm F3.5- 5.6 DC lens uses an inner focusing system to move the secondary lens apparatus.
	www.sigma-photo.co.jp /english/lens (1110 words)

	Nikon CRC and Aspherical Lens Elements (Site not responding. Last check: 2007-10-28)
		Aspherical lenses are also used to improve the optical quality, but in a different sense.
		Aspherical means that if you have a spherical lens of focal f, "light" passing through the border of the lens has not the same focal plane as the one passing through the lens center.
		Hence, Nikon uses "aspherical" lenses to correct this optical defect: these are lenses with different lens radii (a spherical lens has only one radius r or curvature) and do not have the same overall curvature.
	wpxx02.toxi.uni-wuerzburg.de /~winstel/walter/crc.html (533 words)

	Edge: Work-Group Computing Report: Fujifilm Engineers Digital Camera Breakthrough With Miniature Photographic ...
		This lens technology advance has also allowed Fujifilm to develop a lens mechanism small enough for its signature 700 series of digital cameras, and the maiden appearance of this new lens will be in Fujifilm's soon-to-be-available MX-1700 ZOOM Digital Camera.
		With an aspherical lens, the lens' curved surface does not conform to the shape of a sphere, rather it is a convergent lens (thicker at the center than at the edges) that bends parallel light rays toward one another.
		The image formed by a converging lens depends on the position of the object relative to the lens face length (distance between the focus and the optical center) and its outer curvature.
	www.findarticles.com /p/articles/mi_m0WUB/is_1999_Sept_6/ai_55660054 (894 words)

	Encyclopedia topic: Photography (science of) (Site not responding. Last check: 2007-10-28)
		This design is necessary for wide angle lens (additional info and facts about wide angle lens) es on manual cameras, since otherwise the last lens would need to be so close to the film so as to interfere with the mirror.
		Aberrations can be reduced dramatically by using an aspherical lens, but these are more complex to grind than spherical or cylindrical lenses.
		To obtain optimum image quality, a camera will not use Fresnel lens (Lens composed of a number of small lenses arranged to make a lightweight lens of large diameter and short focal length) es, although this would reduce the weight of lens which can be significant, especially for telephoto zoom lenses.
	www.absoluteastronomy.com /encyclopedia/p/ph/photography_(science_of).htm (511 words)

	Canon Technology -Aspherical Lenses- (Site not responding. Last check: 2007-10-28)
		Aspherical lenses have a curvature that changes continuously in the direction of the lens diameter.
		Aspherical lens production technology incorporates Canon's unique technologies including the die molding technology, which is said to be most difficult aspect of lens production.
		This method is utilized in the aspherical lens of compact cameras and contributes to downsizing of cameras.
	www.canon.com /technology/p_tech/06.html (301 words)

	Remote control system for locking/unlocking the doors of motor vehicles with aspherical toroidal lens containing ...
		A remote control system according to claim 1, wherein the lens is delimited by an inside surface in the form of a circular cylinder about said vertical axis and by said toroidal aspherical outside surface, thereby constituting a body of revolution about said vertical axis.
		A remote control system according to claim 1, wherein the lens having said toroidal aspherical outside surface is solid and is provided with a plurality of slots designed to receive the photosensitive cells, said slots opening out into a lateral face of the lens extending transversely to said vertical axis.
		By making the lens 100 in the form of a solid toroidal aspherical lens, it is possible to ensure that the photosensitive cells 210, 220, and 230 are positioned accurately, automatically and reliably.
	www.freepatentsonline.com /5191324.html (2020 words)

	Sigma Wide
		It incorporates aspherical lenses in the front and rear lens group to minimise distortion, astigmatism, and spherical aberration.
		SIGMA introduces the 20-40mm f2.8 DG Aspherical lens, a large-aperture-wide-zoom lens with 20-40mm focal length range, f/2.8 brightness plus 30cm (11.8in) minimum focusing distance throughout the zoom range, and 1:4.6 maximum photography magnification that is also suitable for digital SLR cameras.
		Contributing to superior optical ability and performance are aspherical lens elements in the front and rear lens groups which minimise distortion by compensating for astigmatic and spherical aberration.
	www.ffordes.com /sigma/zoomwide.htm (451 words)

	Sigma - Lenses
		This large-aperture wide-angle lens is equipped macro focusing capability with a maximum magnification of 1:2.7 and fast F1.8 maximum aperture.
		This lens is capable of Macro photography at minimum focusing down to 18cm (7.1 inch) (reproduction ratio 1:2.7).
		It is easy to hold the lens, since the focusing ring does not rotate during auto-focus, yet it provides adequate focusing torque of the focusing ring during manual focusing of the lens.
	www.sigmaphoto.com /lenses/lenses_all_details.asp?id=3281&navigator=4 (254 words)

	CCICameraCity.com - Cameras, Camcorders, Digital, Electronics, Accessories (Site not responding. Last check: 2007-10-28)
		This lens establishes a new benchmark as a standard lens, extending from a wide 28mm all the way to 105mm telephoto, all with a fast constant 2.8 maxi...
		AF 70-300mm f/4-5.6 LD This super-telephoto lens with a high zoom ratio covers a wide range of nearly 4.3x yet is only 115.5mm(4.5").
		A standard zoom lens from a wide 28mm to a medium telephoto range of 80mm.
	www.ccicameracity.com /category.asp?catid=142 (350 words)

	[No title] (Site not responding. Last check: 2007-10-28)
		Aspherical lenses minimize the problem of coma and other types of lens distortion - even when used at the widest aperture.
		aspherical lenses are made with a special optical resin molded onto optical glass and are used in several Nikkor zoom lenses.
		aspherical lenses are manufactured by molding a unique type of optical glass using a special metal die technique.
	www.nikonians.org /cgi-bin/dcforum/dcboard.cgi?az=printer_format&om=166&forum=DCForumID14 (346 words)

	Sigma 28-300mm f/3.5-6.3 Hyper Zoom Aspherical AF Lens - abesofmaine.com/dev Cameras and Electronics
		Aspherical lenses provide excellent correction for all types of aberration while making a very compact construction possible.
		This lens has a minimum focusing distance of 50cm (19.69 inches) at all focal lengths.
		The lens materials used in this new lens are lead and arsenic free ecological glass.
	www.abesofmaine.com /viewproduct.asp?id=sg28300chzaf (314 words)

	New Canon 400mm f/4 DO IS USM: Digital Photography Review (Site not responding. Last check: 2007-10-28)
		A full commercial version of the lens should be available in the first half of 2001.
		The most significant characteristic of the diffractive optical element is that the positions where the wavelengths combine to form an image are reversed from those of a refractive optical element.
		This lens achieves the same high level of image quality as that of comparable super telephoto lenses incorporating only refractive optical elements.
	www.dpreview.com /news/0009/00090604canon_400do.asp (954 words)

	Epson RD-1 Lens Report
		Some lens experts believe that the current aspherical M lenses are the best lenses Leica has ever produced and among the best that any company has ever produced.
		It may work satisfactorily with smaller lens openings and with subjects that are not too close to the camera but for other situations its inability to be rangefinder focused is a handicap.
		In other words, the lens has a tendency to render the contrast range in the subject in such a way that it is sometimes beyond the dynamic range of the camera.
	www.luminous-landscape.com /reviews/lenses/rd-1-lens.shtml (10009 words)

	Product Review: Voigtlander Ultra Wide 12mm lens
		But the most remarkable lens of all would have to be the Voigtländer Ultra Wide Heliar 12 mm f5.6 Aspherical Lens.
		To its credit, the lens appears sharp right to the corners at every aperture (something that can't be said of most super-wide SLR lenses).
		Rather, the Heliar 12mm creates images not possible with any other lens and inspires a totally different approach to street photography in which depth of field and shutter speeds are no longer critical.
	www.apogeephoto.com /dec2000/Voigtlander_ultra.shtml (796 words)

	Sigma 17-35mm F2.8 EX Aspherical HSM Lens for Nikon-AF Camera by Sigma Corporation
		Also, by incorporating aspherical lens elements in the front and rear lens groups, it corrects spherical aberration that could distort your images.
		The internal focusing system prevents the deterioration of optical quality when you are at a close distance to your subject, and it eliminates the rotation of the front barrel during focusing.
		The lens materials used in this lens are lead-free and arsenic-free ecological glass.
	www.geocities.com /nikon_online/Sigma_17_35mm_F2_8_EX_Aspherical_HSM_Lens_for_Nikon_AF_Camera_B0000501TN.htm (193 words)

	Tamron AF 18-300mm XR DI f/3.5-6.3 (Site not responding. Last check: 2007-10-28)
		The lens, which is just 84mm long, features enhanced peripheral illumination, minimizes peripheral light fall-off and its internal surface coating reduces ghosting and flare.
		In addition, three hybrid aspherical lens elements and two LD (Low Dispersion) glass elements are used to accomplish effective compensation of on-axis and lateral chromatic aberrations, a critical factor to enhance the optical quality in digital photography.
		The lens is a multi-purpose zoom lens, yet excellent portability and ease of use are assured.
	www.jjmehta.com /products/tamronaf18200xrdi.html (1219 words)

	DOE (Site not responding. Last check: 2007-10-28)
		A commercial version of this lens is to be marketed during the first half of 2001.
		These optical elements are now found in a diverse range of lens products, such as interchangeable SLR camera lenses, and lenses for video camcorders and digital cameras.
		To make a lens smaller and lighter, the spacing between the elements is shortened and the refractive properties of the front and rear lens groups are made more pronounced.
	www.canon.com /do-info (838 words)

	Sigma - Lenses
		An aspherical lens satisfactorily compensates for distortion aberration throughout the zoom range.
		An aspherical lens satisfactorily compensates for distortion aberration and produces a top quality optical performance throughout the entire zoom range.
		This lens also incorporates a double-cam inner focusing zoom system that ensures compact and lightweight lens with excellent imaging capability and easy to use.
	www.sigmaphoto.com /lenses/lenses_all_details.asp?id=3268&navigator=2 (141 words)

	Shutterbug: Sigmas 20mm f1.8 EX DG Aspherical RF Lens (Site not responding. Last check: 2007-10-28)
		It is also an ideal lens for digital SLRs, as the loss of coverage due to a smaller capture frame forces the use of a superwide on a digital SLR to get moderate wide angle coverage.
		The Sigma 20mm f/1.8 EX DG Aspherical RF is one of several Sigma lenses in this class, which includes the 8mm f/4 fisheye, the 14mm f/2.8, the 15mm f/2.8, and their 24mm f/1.8 and 24mm f/2.8 lenses.
		Sigma claims that this is the first 20mm superwide lens with a large aperture of f/1.8 and angle of view of 94.5°.
	www.shutterbug.net /test_reports/0901sb_get (1203 words)

	[No title] (Site not responding. Last check: 2007-10-28)
		To block unwanted light, one lens group has a flare-cutting diaphragm matching the image size and because the front lens group is fixed, further adjustment of a circular polarizing filter after focusing is not necessary.
		Designed as a premier lens in the most popular wide angle fixed focal length category, the EF 28mm f/1.8 USM's fast aperture enables photographers to shoot under extreme lighting conditions, while providing an opportunity for faster shutter speeds under normal lighting conditions.
		The lens design provides an extremely close focusing distance of less than 10 inches, the shortest in its class Unlike most conventional wide angle lenses, the front lens group in the EF 28mm f/1.8 is fixed and does not rotate during focusing.
	bobatkins.photo.net /info/faq30/28F18.HTM (304 words)

	The Panorama Factory Forum: Aspherical Lens (Site not responding. Last check: 2007-10-28)
		I downloaded the trial version and tried to stitch a sequence taken with a Nikon D1 and a 14mm aspherical lens (~24mm lens at 35mm format equivalent) with no success at all.
		Whether the lens is aspherical is probably not the issue.
		Aspherical elements are used in lens design to improve the optical quality of the lens system by reducing "spherical aberration." A spherical lens does not focus parallel rays to a point, but rather along a line.
	www.panoramafactory.com /cgi-bin/discus/show.cgi?tpc=10&post=288 (368 words)

	FM Reviews - 24-70mm f2.8 EX Aspherical DG DF (Site not responding. Last check: 2007-10-28)
		It is easy to hold the lens, since the focusing ring does not rotate during auto focusing, and yet provides a wide focus ring for easy to use manual focus.
		Since the front of the lens does not rotate, it allows the use of a flower shaped "Perfect Hood" and facilities the use of polarizing filters.
		Mine was acceptably sharp for a $400 lens, but not as sharp as copies of the 24-70L and Tamron 28-75 I've seen.
	www.fredmiranda.com /reviews/showproduct.php?product=97&sort=7&cat=37&page=1 (1719 words)

	Nikon Corporation Imaging Company: Choosing The Right Lenses: Optical Technologies 01
		To enhance the performance of its optical lens elements, Nikon employs an exclusive new multilayer lens coating that helps reduce ghost and flare to a negligible level.
		Thanks to Aspherical Lens Elements, lenses incorporating special optical characteristics can be made.
		The world's fastest 28mm lens, the AF Nikkor 28mm f/1.4D, uses an aspherical element to ensure its compact size and to obtain superb performance by eliminating sagittal, or arrow-shaped, coma, even at its widest aperture.
	www.nikon-image.com /eng/LensGuide/opt_tech.html (365 words)

	Sigma 17-35mm f/2.8-4 EX DG Aspherical HSM Zoom Lens
		A super wide-angle zoom lens with a 104 degrees angle of view, and large aperture.
		Two pieces of molded glass aspherical lens elements offer excellent correction for distortion as well as all types of aberration.
		It is an ideal lens for Digital SLR Cameras as well as film SLR cameras.
	www.hotbuyselectronics.com /sigma_17_35mmexdghsm.htm (267 words)

	Tamron AF 18-200 mm F3.5 - F6.3 Di-II: Digital Photography Review
		The new AF18-200mm F/3.5-6.3 XR Di-II LD Aspherical (IF) MACRO is a high power zoom lens designed for exclusive use with digital SLR cameras using smaller-size imagers and inherits the product concept of the existing AF28-300mm F/3.5-6.3 XR Di zoom lens.
		The zoom lens uses a new optical system designed to confine the changing angles of incidences of light rays reaching the imager within a certain scope over the entire image field from the center to the periphery, by considering the effects of variances due to zooming.
		Since the lens is designed exclusively for digital SLR photography, it provides high image quality in terms of resolution, contrast and flatness of image field.
	www.dpreview.com /news/0502/05022105tamron_18-200mm.asp (1141 words)

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