Abstract: An optical system includes, in order from an object side to an image side, a front unit having a positive refractive power, an aperture diaphragm, and a rear unit. The front unit includes a first lens unit having a positive refractive power. The rear unit includes a second unit adjacent to the aperture diaphragm and configured to move in focusing. The first lens unit includes n (which is an integer of 2 or higher) positive lenses and one or more negative lenses. The materials of at least two positive lenses in the first lens unit satisfy 0.0100<??gF where ??gF is an abnormal partial dispersion of each material. The material of the one or more positive lenses satisfies 0.0272<??gF. Additional conditional expressions are satisfied.

Abstract: A projection lens system includes, in order from the magnified side to the reduced side thereof, a first lens group with negative refractive power, a second lens group with a positive refracting power, and a spatial light modulator. The projection lens system satisfies the following condition: 3.478<BFL/F<3.528. Wherein: BFL is a back focal length of the projection lens system; F is an effective focal length of the projection lens system.

Abstract: A lens system with positive refraction power, in order from the object-side to the image-side, includes a first lens group with negative refraction power and a second lens group with positive refraction power. The first lens group includes a first lens with negative refraction power, a second lens with positive refraction power, and a third lens with positive refraction power. The second lens group includes a fourth lens with negative refraction power, a fifth lens, and a sixth lens. The lens system satisfies the following condition: 5<D/F<5.3, wherein: D is a total length of the lens system; F is a focal length of the lens system.

Abstract: A lens system with positive refraction power, in order from the object-side to the image-side, includes a first lens group with negative refraction power and a second lens group with positive refraction power. The first lens group includes a first lens with negative refraction power, a second lens with positive refraction power, and a third lens with positive refraction power. The second lens group includes a fourth lens with negative refraction power, a fifth lens, and a sixth lens. The lens system satisfies the following condition: 5<D/F<5.3, wherein: D is a total length of the lens system; F is a focal length of the lens system.

Abstract: To realize an image pickup lens that can be applied to an image pickup module in which a solid-state image sensing device is used, that allows a reduction in manufacturing cost, and that easily maintains its desired resolving power, etc., the second lens has a surface facing the subject, and the surface includes a central portion sticking out toward the subject and a peripheral portion surrounding the central portion and sinking in toward the image surface. Further, the image pickup lens satisfies the mathematical expression 0.30<d1/d<0.45, where d1 is the length of a segment between the center of that surface of the first lens which faces the subject and the center of that surface of the first lens which faces the image surface and d is the whole optical length of the image pickup lens.

Abstract: An optical system includes a negative lens unit including one or more negative lenses located closest to an object side, and a positive lens unit having positive refractive power including a plurality of lenses on an image side of the negative lens unit. When the one or more negative lenses are denoted by negative lenses LNi (i=1, 2, . . . ) in order from the object side, and a portion of lenses among the plurality of the lenses constituting the positive lens unit is denoted by lenses LAj (j=1, 2, . . . ) in order from the object side, a focal length fni of the negative lens LNi, a refractive index Nni of a material thereof, a focal length fAj of the lens LAj, a refractive index NAj, and partial dispersion ratio ?gFAj of a material of the lens LAj are set to satisfy respective predetermined conditions.

Abstract: According to the present invention, a small-sized double-lens imaging optical system whose chromatic aberration is corrected even at a super wide angle of 150° or more can be provided. The double-lens imaging optical system of the present invention includes a concave lens, and a convex lens having a diffraction grating provided thereon, and satisfies the following conditional expression (1): 4.5<P1=(1?f/fa)·?d<9.0??(1). Herein, f is an effective focal length of the double-lens imaging optical system; fa is an effective focal length of the double-lens imaging optical system excluding the diffraction grating; and ?d is an Abbe number of the material of the convex lens with respect to the d-line. As a result, chromatic aberration can be well corrected even with respect to rays entering at high angles of view.

Abstract: A micro-lens module including a first lens group and a second lens group is provided. The first lens group is disposed between an object side and an image side, wherein a surface closest to the object side in the first lens group is a first aspheric surface, whose radius of curvature is r1. A surface closest to the image side in the first lens group is a second aspheric surface, whose radius of curvature is r2. The second lens group is disposed between the first lens group and the image side, wherein a surface closest to the first lens group in the second lens group is a third aspheric surface, whose radius of curvature thereof is r3. A surface closest to the image side in the second lens group is a fourth aspheric surface. The micro-lens module satisfies: 0.6>r1>0.4 mm, and 0.3<r1/r2<0.6.

Abstract: An imaging lens includes a first lens group having a positive refractive power, an aperture stop, and a second lens group having a positive refractive power, which are disposed in order from an object. The first lens group has a first lens component having a negative refractive power and a second lens component having a positive refractive power, which are disposed in order from the object, and conditions expressed by the expressions 0.12<f/f1<0.47 and 0.016<D12/f<0.079 are satisfied, when f1 is a focal length of the first lens group, f is a focal length of the imaging lens, and D12 is an air distance between the first lens component and the second lens component of the first lens group.

Abstract: An imaging optical system includes an aperture stop, a first lens group disposed on an object side of the aperture stop, a second lens group disposed on an image side of the aperture stop and a plate-like ND filter disposed close to a position of the aperture stop in an optical axis direction of the first and second lens groups, and the second lens group includes positive refracting power as a whole, the ND filter is configured to be retractable from the optical axis, and to attenuate a passing light amount.

Abstract: A superwide-angle lens system includes a negative first lens group, an aperture diaphragm, and a positive second lens group. The first lens group includes two negative meniscus lens elements, and a positive lens element. The second lens group includes a cemented lens having negative and positive lens elements; and a positive lens element. The following conditions (1) and (2) are satisfied: ?1.45<f12/f<?1.15??(1) 1.4<SF2<2.4??(2) f12: the combined focal length of the two the negative meniscus lens elements in the first lens group, f: the focal length of the lens system, SF2: the shaping factor of the negative meniscus lens element on the image side in the first lens group.

Abstract: Provided are an imaging optical system in which chromatic aberrations are excellently corrected across the entire screen to realize high optical performance, and an optical apparatus including the imaging optical system. In an imaging optical system of which a back focus is longer than a focal length, a lens unit located in a reduction-conjugate side of an aperture stop includes at least one positive lens. A partial dispersion ratio and an Abbe number of the positive lens are set such that a refractive index, a position, and a power satisfy a suitable relationship.

Abstract: A lens module includes a barrel, a first lens, a second lens, and a spacer. The first lens and the second lens are received in the barrel from an object side to an image side of the lens module. Each lens includes an optical portion and a non-optical portion around the optical portion. The spacer is positioned between the non-optical portion of the first lens and the non-optical portion of the second lens. The second lens includes an image-side surface. The non-optical portion on the image-side surface includes a contact portion. The contact portion defines a triangular notch.

Abstract: A micro-lens module including a plurality of lens groups is provided. The lens groups are disposed between an object side and an image side, wherein at least one lens group in the lens groups is composed by a complex lens. The complex lens includes a plurality of lenses, the lenses are adhered to each other, and an index of at least one lens in the lenses is different from indexes of the other lens in the lenses. The provided micro-lens module has an improved imaging quality and a miniaturized size while considering a manufacturing convenience.

Abstract: The present invention discloses a lens assembly and a camera module having the lens assembly. An aspect of the present invention provides a lens assembly that can include: a barrel arranged having a space inside thereof; a first lens accommodated in the space; a second lens stacked over the first lens and arranged to be separated from the first lens; and a cap installed over the barrel and configured to provide a load to support the second lens to the barrel.

Abstract: A variety of optical arrangements and methods of modifying or enhancing the optical characteristics and functionality of these optical arrangements are provided. The optical arrangements being specifically designed to operate with camera arrays that incorporate an imaging device that is formed of a plurality of imagers that each include a plurality of pixels. The plurality of imagers include a first imager having a first imaging characteristics and a second imager having a second imaging characteristics. The images generated by the plurality of imagers are processed to obtain an enhanced image compared to images captured by the imagers.

Abstract: A wafer-level lens of the present invention is produced by cutting out one of a plurality of lenses from at least one lens array having a wafer on which the plurality of lenses are provided, the wafer-level lens being cut out from the at least one lens array so as to have a cross section which is perpendicular to an optical axis of the wafer-level lens and is a hexagon.

Abstract: A lens module includes a lens barrel, a first lens, an opaque plate, and a second lens. The first lens includes an imaging portion and a non-imaging portion surrounding the imaging portion. The non-imaging portion defines an annular conic surface. The opaque plate is annular conic shaped and contacts with the annular conic surface. The second lens includes an imaging portion and a non-imaging portion surrounding the imaging portion. The object-side surface of the non-imaging portion of the second lens is step-like shaped and includes at least two step surfaces. A junction of two adjacent step surfaces abuts against the opaque plate.

Abstract: An image taking optical system, sequentially arranged from an object side to an image side along an optical axis comprising: a front lens group, a stop and a rear lens group. The front lens group comprises at least a meniscus front-group first lens element with a convex object-side surface. The rear lens group comprises at least three lens elements. Through the means of field adjustments that result in desirable distorted images, the image taking optical system may shorten the total length while enhancing the ability to create a larger field of view for panorama usages in compact cameras and mobile phones.

Abstract: A Ca—La—F based transparent ceramic, including: mixing CaF2 particles and LaF3 particles that are prepared separately from the CaF2 particles to form a mixed body of particles, and sintering the mixed body of particles and making the mixed body transparent, thereby producing a transparent ceramic.

Abstract: An optical imaging system includes a first lens group having a positive or negative optical power, an aperture diaphragm, and a second lens group having a positive optical power arranged in order from an object side. The first lens group includes a first front lens group having at least two negative lenses and a first rear lens group having at least one positive lens with an airspace in-between the first front and rear lens groups. The second lens group includes a second front lens group having first positive and negative lenses, second negative and positive lenses arranged in order from the object side, and a second rear lens group including at least one aspherical lens. When focusing on an object in a close range from infinity, the second lens group moves to the object side while an interval between the second front and rear lens groups are shortened.

Abstract: An optical unit with a first lens group and a second lens group, the first lens group and the second lens group being sequentially arranged from an object side to an image plane side, the first lens group including a first lens element, a transparent body, and a second lens element, the first lens element, the transparent body, and the second lens element being sequentially arranged from the object side to the image plane side, the second lens group including only a third lens element.

Abstract: A lens system includes a main lens and a transfer lens aligned with the main lens. The optical axis of the main lens is superposed on that of the transfer lens. The transfer lens includes, in order from the object side to the image side thereof, a first lens having negative refraction power, and a second lens having positive refraction power. The lens system satisfies the following conditions: 0.4<|f1/f2|<0.8; 2<v1/v2<3.8; 0.86<N1/N2<1.12; wherein, f1 is a focal length of the first lens, f2 is a focal length of the second lens, v1 is an Abbe constant of the first lens, v2 is an Abbe constant of the second lens, N1 is a refractive index of the first lens, N2 is a refractive index of the second lens.

Abstract: [Object] To provide an optical unit and an image pickup apparatus that are capable of realizing a high-resolution and high-performance image pickup system. [Solving Means] An image pickup lens (100) includes a first lens group (110) and a second lens group (120) that are sequentially arranged from an object side (OBJS) to an image plane (140) side. The first lens group (110) includes a first lens element (111), a second lens element (112), a first transparent body (113), and a third lens element (114) that are sequentially arranged from the object side (OBJS) to the image plane (140) side. The second lens group (120) includes a fourth lens element (121), a second transparent body (122), a second buffer layer (123), and a fifth lens element (124) that are sequentially arranged from the object side (OBJS) to the image plane (140) side. The first lens element (111) and the second lens element (112) of the first lens group (110) form a doublet lens.

Abstract: Disclosed are a lens assembly and a camera module. The lens assembly includes a lens unit and a spacer provided at an upper portion or a lower portion of the lens unit. The spacer includes polymer having the glass transition temperature of about 140° C. to about 500° C.

Abstract: A lens assembling method for assembling a first lens and a second lens where the first lens has a first mark on a first surface thereof and a second mark on a second surface opposite to the first surface, and the second lens has a third mark on a first surface thereof, the lens assembling method including: a first step of aligning a position of one of the first mark and second marks of the first lens with a position of the third mark of the second lens; and a second step of aligning a position of the other one of the first and second marks of the first lens with the position of the third mark of the second lens, while keeping the position alignment performed in the first step.

Abstract: An imaging lens system with two lenses is provided. The imaging lens system with two lenses, along an optical axis from an object side to an image side, comprises an aperture stop; a first lens having positive refractive power and being a biconvex lens; and a second lens having negative refractive power and being a meniscus lens with a concave surface on the object side and a convex surface on the image side.

Abstract: An optical system includes, in order from an object side to an image side, a first lens unit, a stop, and a second lens unit. The first lens unit includes a first negative lens having a meniscus shape and a negative refractive power at a position closest to the object side and a negative lens Gn having a negative refractive power at a position closer to the image side than the first negative lens. The second lens unit includes a positive lens Gp having a positive refractive power. A material of each of the negative lens Gn and the positive lens Gp satisfies the following condition: ?gF?(?0.001682·?d+0.6438)?0.01 where “?d” denotes an Abbe number of a lens material and “?gF” denotes a relative partial dispersion with respect to g-line light and F-line light.

Abstract: An imaging optic comprising a first combination element comprised of at least two individual lens elements, aligned with each other along an optical axis and adhered to each other, a second combination element comprised of at least one individual lens element and an aperture disposed between the first and second combination elements, the surfaces of the imaging optic having less than about 3 minutes tilt relative to the optical axis and less than about 0.005 mm de-center relative to the optical axis. A method of making the imaging optic and an endoscope comprising the imaging optic.

Abstract: A lens component of the present invention is made by cementing a lens LA and a lens LB having a refracting power smaller than a refracting power of the lens LA, and satisfies predetermined conditional expressions. Moreover, in an image forming optical system of the present invention which includes a lens group B having a negative refracting power, a lens group C having a positive refracting power and which moves only toward an object side at the time of zooming from a wide angle end to a telephoto end, and one or two more lens groups additionally, one of the lens components of the present invention is used in the lens group B.

Abstract: A variable magnification optical system includes first lens group having negative refractive-power, an aperture-stop and second lens group having positive refractive-power, arranged from the object-side. A negative lens having a concave surface facing the image-side is arranged on the most object side of the first lens group, and an aspheric lens having a concave surface facing the object-side and an aspheric surface facing the image-side is arranged on the most image side of the first lens group. A positive lens having a convex surface facing the image-side is arranged, on the object-side of the aspheric lens, immediately before the aspheric lens. The image-side surface of the aspheric lens at the most image side of the first lens group includes a portion having higher positive power on the outside of positions through which outermost rays of an axial beam pass, compared with the vicinity of the optical axis.

Abstract: An optical system and an optical apparatus capable of properly correcting chromatic aberration over a visible wavelength range are obtained. An optical system includes a diffractive optical element and a refractive optical element on at least one of an object side and an image side of a stop. The following conditions are satisfied: |??gd|>0.038 0.003<|??dC|<0.038 (?R×?d×??dC)×(??D)<0 where ?d represents an Abbe number of the refractive optical element, ?gd represents a partial dispersion ratio for a g-line and a d-line, ?dC represents a partial dispersion ratio for the d-line and a C-line, ?R represents an optical power provided when light incident and exit surfaces of the refractive optical element are both in contact with air, and ?D represents an optical power of the diffractive optical element. Here, ??gd=?gd?(?1.687×10?7·?d3+5.702×10?5·?d2?6.603×10?3·?d+1.462), and ??dC=?dC?(?0.1968?gd+0.5480).

Abstract: Provided is an imaging optical system and an image acquisition apparatus that can be suitably used in a small-diameter endoscope while having an ultra-wide angle of view. Provided is an image optical system (1) containing, in order from the object side, a negative front group (FG), an aperture stop (S), and a positive back group (BG), wherein the front group (FG) contains, in order from the object side, a negative first lens (L1) and a negative second lens (L2), and the back group (BG) contains a cemented lens (CL) constituted of at least three lenses (L5, L6, L7) joined together.

Abstract: The present invention provides an apparatus and a system for improving depth of focus (DOF), wherein an optical lens for optical processing is actuated to vibrate whereby the DOF of the optical processing is increased due to the variation of focal point. In the embodiment of the present invention, an actuator is coupled to the optical lens for providing vibration energy wherein the optical lens is actuated by the vibration energy so as to vibrate on an optical axis thereof so as to increase the DOF during the optical processing, thereby improving the quality and efficiency of optical processing.

Abstract: A wide angle lens includes sequentially from the object side, a first lens group having a negative refractive power; an aperture stop; and a second lens group having a positive refractive power, where the first lens group includes sequentially from the object side, a negative first lens having on the object side, a convex surface; a negative second lens having on the image side, a concave surface; a negative third lens; and a positive fourth lens. The second lens group includes sequentially from the object side a cemented lens having a positive refractive power and formed by a fifth lens and a sixth lens; a positive seventh lens; and a negative eighth lens having on the image side, a concave surface.

Abstract: A rear focus wide-angle lens system includes a first lens group, a diaphragm, and a second lens group, in this order from the object. The second lens group is moved along the optical axis of the lens system when focusing is performed from infinity to an object at a closer distance. The rear focus wide-angle lens system satisfies the condition 1.5 <F1/F2<3.0, wherein F1 designates the focal length of the first lens group and F2 designates the focal length of the second lens group.

Abstract: A lens assembly comprises a first lens and a second lens. The first lens includes a first central round portion and a first peripheral stepped portion surrounding the first central round portion. The first peripheral stepped portion comprises a downward-facing surface, a first supporting surface, and a first inclined surface interconnected. The second lens includes a second central round portion and a second peripheral stepped portion surrounding the second central round portion. The second peripheral stepped portion includes an upward-facing surface, a second inclined surface, a third surface, and a second supporting surface. The second lens is engaged on the first lens in a manner that the first supporting surface contacts the second supporting surface, the downward-facing surface is facing toward the upward-facing surface, the first inclined surface contacts the second inclined surface but a gap is defined between the first inclined surface and the third surface.

Abstract: An optical lens which, in a controlled manner, and without altering either the resolution or luminous capture, helps to extend the depth of field of any other optical system. The optical lens of the present invention is composed of two optical lenses that form a pair. Each of the lenses of the pair produces a change of optical path with a symmetrical distribution. If there is no relative displacement, the lenses of the pair generate an optical path difference equal to zero. When there is relative displacement, the lenses of the pair generate a change of optical path with asymmetric distribution, which helps to extend the depth of field without reducing either the resolution or luminous capture. The optical lens of this invention, in the form of an optical pair, serves any other optical system to capture images without loss of modulation, but with attenuated modulation which can be retrieved with digital processing algorithms known in the art.

Abstract: An imaging optical system, including a first lens group; an aperture stop; a second lens group having a positive power, the first lens group, the aperture stop and the second lens group being arranged from a side of an object sequentially, wherein the second lens group includes a second front lens group having a positive power and a second rear lens group having a positive power, the second front lens group and the second rear lens group being arranged sequentially from the object side, wherein, when focusing from an infinity-distance object to a short-distance object, the first lens group and the aperture stop are fixed, and the second front lens group and the second rear lens group are moved with a mutually different movement amount.

Abstract: An imaging system comprises a rolling-reset imager that forms an electronic image of an object, a light source illuminating the object with pulsed light, and a bandpass optical filter disposed between the object and the rolling-reset imager. The pulsed light has an illumination frequency spectrum and an illumination pulse width defining an effective exposure time for forming the image of the object. The bandpass optical filter has a frequency pass band permitting transmission of a significant portion of the illumination frequency spectrum while at least approximately inhibiting transmission of at least some light having frequencies outside the illumination frequency band. An imaging method illuminates an object with light in a given frequency range, so that the illumination light reflects from the object along with background light. The method filters the reflected light so as to attenuate at least some of the background light by a greater attenuation factor than the illumination light.

Abstract: An objective lens for an optical pickup device is provided with a light-source-side lens surface by which laser light is converged, and a disc-side lens surface by which the laser light converged on the light-source-side lens surface is converged. In this arrangement, assuming that a projection area S1 is an area of the light-source-side lens surface when the light-source-side lens surface is viewed from an optical axis direction of the objective lens, and a projection area S2 is an area of the disc-side lens surface lens surface when the disc-side lens surface lens surface is viewed from the optical axis direction of the objective lens, the projection area S1 and the projection area S2 satisfy the following formula: S1/S2?2.0.

Abstract: A miniature image capture lens is disclosed, comprising a wafer scale lens system, which comprises a first lens group including a first substrate, a first surface disposed on a first side of the first substrate, a second surface disposed on a second side of the first substrate, and a second lens group including a second substrate, a third surface disposed on a first side of the second substrate, and a fourth surface disposed on a second side of the second substrate, wherein the first surface, the second surface, the third surface and the fourth surface are aspherical, one of the first surface and the second surface, and one of the third surface and the fourth surface have a high refraction index Nd_h and a high abbe number Vd_h, another one of the first surface and the second surface, and another one of the third surface and the fourth surface have a low refraction index Nd_l and a low abbe number Vd_l, and the miniature image capture lens meets the following conditions: Nd—h=1.58˜1.62; Nd—l=1.48˜1.

Abstract: An optical system includes a positive lens unit, wherein the positive lens unit includes an optical element containing a base material and minute particles that are mixed with the base material and have Abbe number that is lower than that of the base material, and the minute particles are higher in density at a peripheral portion of the optical element than on an optical axis of the optical element.

Abstract: This invention provides a compact imaging lens assembly in order from an object side toward an image side including a first lens with positive refractive power having at least one of the object-side and image-side surfaces thereof being aspheric, a second lens with negative refractive power having a concave object-side surface and a concave image-side surface with at least one of both surfaces thereof being aspheric, and an aperture stop positioned between the first lens element and the second lens element. There are two lens elements with refractive power in the compact imaging lens assembly.

Abstract: A fixed-focus lens disposed between a magnified side and a minified side. The fixed-focus lens has an optical axis and includes a reflective system and a refractive system. The reflective system includes a reflection mirror with a negative refractive power. The refractive system is disposed between the reflection mirror and the minified side and includes a first lens group and a second lens group. The first lens group has a positive refractive power. The second lens group is disposed between the first lens group and the minified side, and has a positive refractive power. The fixed-focus lens satisfies F/H>0.23, where F is an effective focal length and H is an image height.

Abstract: A lens array unit includes first lens array plates, second lens array plates and a support member. Each of the first lens array plate has multiple first lenses thereon. Each of the first lenses has a first optical axis that extends in a first direction and the first lenses are arranged in a second direction perpendicular to the first. Each of the second lens array plates has multiple second lenses thereon. Each of the second lenses has a second optical axis that extends in the first direction and the second lenses are arranged in the second. The support member has opposite first and second sides. The support member extends in the second direction to support the first lens array plates on the first side and support the second lens array plates on a second side so that each of the first lens array plates opposes a different corresponding one of the second lens array plates.

Abstract: The present invention provides a wide-viewing-angle imaging lens assembly comprising, in order from an object side to an image side: a front lens group, a stop, and a rear lens group. The front lens group comprises, in order from the object side to the image side: a first lens element with negative refractive power having a concave image-side surface and a second lens element. The rear lens group comprises, in order from the object side to the image side: a third lens element with positive refractive power having a concave object-side surface and a convex image-side surface, a fourth lens element with positive refractive power having a convex object-side surface and a convex image-side surface, and a fifth lens element with negative refractive power having a concave object-side surface. Such an arrangement of optical elements can effectively enlarge the field of view of the wide-viewing-angle imaging lens assembly, reduce the sensitivity of the optical system, and obtain good image quality.

Abstract: A line generator according to the present invention includes a light source, a first lens group, and a second lens group. An optical axis is set to a position of a light beam which travels orthogonal to incidence surfaces of both the first and second lens groups and the first lens group is configured such that light beams from the light source are not collimated in a first direction in a plane orthogonal to the optical axis and are collimated or focused only in a second direction orthogonal to the first direction in the plane orthogonal to the optical axis and the second lens group is configured such that the light beams which have passed through the first group form a line.

Abstract: A zoom lens has a negative object side lens unit (or first lens unit G1), a positive image side lens unit (or third lens unit G3), a positive intermediate lens unit (or second lens unit G2), and an aperture stop. The distance between the object side lens unit and the intermediate lens unit is smaller at the telephoto end than at the wide angle end, the distance between the intermediate lens unit and the image side lens unit is larger at the telephoto end than at the wide angle end, the intermediate lens unit moves in such a way that it is located closer to the object side at the telephoto end than at the wide angle end, the image side lens unit moves in such a way that it is located closer to the image side at the telephoto end than at the wide angle end, the aperture stop moves integrally with the intermediate lens unit. The image side lens unit is composed of two lens component including a front lens component and a positive rear lens component arranged in the mentioned order from the object side.

Abstract: In one form, an imaging system comprises an imager that forms an image of an object in a field of view, a rotationally symmetric lens assembly disposed between the imager and the object, and an equalizer. The rotationally symmetric lens assembly provides increased collection efficiency for a given depth of field, whereby the rotationally symmetric lens assembly causes aberration, compared to a well-focused lens. The rotationally symmetric lens assembly comprises a front negative lens, a rear positive lens, and an aperture positioned between the front and rear lenses. The equalizer, which is connected to the imager, receives image data and at least partially compensates for the aberration caused by the rotationally symmetric lens assembly.