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Chapter 3 (Aberrations)
Chapter 3 Aberrations 3.1 Introduction In Chap. 2 we discussed the image-forming characteristics of optical systems, but we limited our consideration to an infinitesimal thread- like region about the optical axis called the paraxial region. In this chapter we will consider, in general terms, the behavior of lenses with finite apertures and fields of view. It has been pointed out that well- corrected optical systems behave nearly according to the rules of paraxial imagery given in Chap. 2. This is another way of stating that a lens without aberrations forms an image of the size and in the loca- tion given by the equations for the paraxial or first-order region. We shall measure the aberrations by the amount by which rays miss the paraxial image point. It can be seen that aberrations may be determined by calculating the location of the paraxial image of an object point and then tracing a large number of rays (by the exact trigonometrical ray-tracing equa- tions of Chap. 10) to determine the amounts by which the rays depart from the paraxial image point. Stated this baldly, the mathematical determination of the aberrations of a lens which covered any reason- able field at a real aperture would seem a formidable task, involving an almost infinite amount of labor. However, by classifying the various types of image faults and by understanding the behavior of each type, the work of determining the aberrations of a lens system can be sim- plified greatly, since only a few rays need be traced to evaluate each aberration; thus the problem assumes more manageable proportions. -
Alternative Processes a Few Essentials Introduction
Alternative Processes A Few Essentials Introduction Chapter 1. Capture Techniques From Alternative Photographic Processes: Crafting Handmade Images Chapter 2. Digital Negatives for Gum From Gum Printing: A Step-by-Step Manual, Highlighting Artists and Their Creative Practice Chapter 3. Fugitive and Not-So-Fugitive Printing From Jill Enfield?s Guide to Photographic Alternative Processes: Popular Historical and Contemporary Techniques 2 Featured Books on Alternative Process Photography from Routledge | Focal Press Use discount code FLR40 to take 20% off all Routledge titles. Simply visit www.routledge.com/photography to browse and purchase books of interest. 3 Introduction A young art though it may be, photography already has a rich history. As media moves full steam ahead into the digital revolution and beyond, it is a natural instinct to look back at where we?ve come from. With more artists rediscovering photography?s historical processes, the practice of photography continually redefines and re-contextualizes itself. The creative possibilities of these historical processes are endless, spawning a growing arena of practice - alternative processes, which combines past, present and everything in between, in the creation of art. This collection is an introduction to and a sample of these processes and possibilities. With Alternative Photographic Processes, Brady Wilks demonstrates techniques for manipulating photographs, negatives and prints ? emphasizing the ?hand-made? touch. Bridging the gap between the simplest of processes to the most complex, Wilks? introduction demonstrates image-manipulation pre-capture, allowing the artist to get intimate with his or her images long before development. In the newly-released Gum Printing, leading gum expert Christina Z. -
Irix 45Mm F1.4
Explore the magic of medium format photography with the Irix 45mm f/1.4 lens equipped with the native mount for Fujifilm GFX cameras! The Irix Lens brand introduces a standard 45mm wide-angle lens with a dedicated mount that can be used with Fujifilm GFX series cameras equipped with medium format sensors. Digital medium format is a nod to traditional analog photography and a return to the roots that defined the vividness and quality of the image captured in photos. Today, the Irix brand offers creators, who seek iconic image quality combined with mystical vividness, a tool that will allow them to realize their wildest creative visions - the Irix 45mm f / 1.4 G-mount lens. It is an innovative product because as a precursor, it paves the way for standard wide-angle lenses with low aperture, which are able to cope with medium format sensors. The maximum aperture value of f/1.4 and the sensor size of Fujifilm GFX series cameras ensure not only a shallow depth of field, but also smooth transitions between individual focus areas and a high dynamic range. The wide f/1.4 aperture enables you to capture a clear background separation and work in low light conditions, and thanks to the excellent optical performance, which consists of high sharpness, negligible amount of chromatic aberration and great microcontrast - this lens can successfully become the most commonly used accessory that will help you create picturesque shots. The Irix 45mm f / 1.4 GFX is a professional lens designed for FujiFilm GFX cameras. It has a high-quality construction, based on the knowledge of Irix Lens engineers gained during the design and production of full-frame lenses. -
Basic View Camera
PROFICIENCY REQUIRED Operating Guide for MEDIA LOAN CALUMET 4X5 VIEW CAMERA Media Loan Operating Guides are available online at www.evergreen.edu/medialoan/ View cameras are usually tripod mounted and lend When checking out a 4x5 camera from Media Loan, themselves to a more contemplative style than the more patrons will need to obtain a tripod, a light meter, one portable 35mm and 2 1/4 formats. The Calumet 4x5 or both types of film holders, and a changing bag for Standard model view camera is a lightweight, portable sheet film loading. Each sheet holder can be loaded tool that produces superior, fine grained images because with two sheets of film, a process that must be done in of its large format and ability to adjust for a minimum of total darkness. The Polaroid holders can only be loaded image distortion. with one sheet of film at a time, but each sheet is light Media Loan's 4x5 cameras come equipped with a 150mm protected. lens which is a slightly wider angle than normal. It allows for a 44 degree angle of view, while the normal 165mm lens allows for a 40 degree angle of view. Although the controls on each of Media Loan's 4x5 lens may vary in terms of placement and style, the functions remain the same. Some of the lenses have an additional setting for strobe flash or flashbulb use. On these lenses, use the X setting for use with a strobe flash (It’s crucial for the setting to remain on X while using the studio) and the M setting for use with a flashbulb (Media Loan does not support flashbulbs). -
Lens Openings and Shutter Speeds
Illustrations courtesy Life Magazine Encyclopedia of Photography Lens Openings & Shutter Speeds Controlling Exposure & the Rendering of Space and Time Equal Lens Openings/ Double Exposure Time Here is an analogy to photographic exposure. The timer in this illustration represents the shutter speed portion of the exposure. The faucet represents the lens openings. The beaker represents the complete "filling" of the sensor chip or the film, or full exposure. You can see that with equal "openings" of the "lens" (the faucet) the beaker on the left is half full (underexposed) in 2 seconds, and completely full in 4 seconds... Also note that the capacity of the beaker is analogous to the ISO or light sensitivity setting on the camera. A large beaker represents a "slow" or less light sensitive setting, like ISO 100. A small beaker is analogous to a "fast" or more light sensitive setting, like ISO 1200. Doubling or halving the ISO number doubles or halves the sensitivity, effectively the same scheme as for f/stops and shutter speeds. 200 ISO film is "one stop faster" than ISO 100. Equal Time One f/stop down In the second illustration, the example on the left, the faucet (lens opening, f-stop, or "aperture"- all the same meaning here) is opened twice as much as the example on the right- or one "stop." It passes twice as much light as the one on the right, in the same period of time. Thus by opening the faucet one "stop," the beaker will be filled in 2 seconds. In the right example, with the faucet "stopped down" the film is underexposed by half- or one "stop." On the left, the "lens" is "opened by one stop." Equivalent Exposure: Lens Open 1 f/stop more & 1/2 the Time In this illustration, we have achieved "equivalent exposure" by, on the left, "opening the lens" by one "stop" exposing the sensor chip fully in 2 seconds. -
Big Bertha/Baby Bertha
Big Bertha /Baby Bertha by Daniel W. Fromm Contents 1 Big Bertha As She Was Spoke 1 2 Dreaming of a Baby Bertha 5 3 Baby Bertha conceived 8 4 Baby Bertha’s gestation 8 5 Baby cuts her teeth - solve one problem, find another – and final catastrophe 17 6 Building Baby Bertha around a 2x3 Cambo SC reconsidered 23 7 Mistakes/good decisions 23 8 What was rescued from the wreckage: 24 1 Big Bertha As She Was Spoke American sports photographers used to shoot sporting events, e.g., baseball games, with specially made fixed lens Single Lens Reflex (SLR) cameras. These were made by fitting a Graflex SLR with a long lens - 20" to 60" - and a suitable focusing mechanism. They shot 4x5 or 5x7, were quite heavy. One such camera made by Graflex is figured in the first edition of Graphic Graflex Photography. Another, used by the Fort Worth, Texas, Star-Telegram, can be seen at http://www.lurvely.com/photo/6176270759/FWST_Big_Bertha_Graflex/ and http://www.flickr.com/photos/21211119@N03/6176270759 Long lens SLRs that incorporate a Graflex are often called "Big Berthas" but the name isn’t applied consistently. For example, there’s a 4x5 Bertha in the George Eastman House collection (http://geh.org/fm/mees/htmlsrc/mG736700011_ful.html) identified as a "Little Bertha." "Big Bertha" has also been applied to regular production Graflexes, e.g., a 5x7 Press Graflex (http://www.mcmahanphoto.com/lc380.html ) and a 4x5 Graflex that I can’t identify (http://www.avlispub.com/garage/apollo_1_launch.htm). These cameras lack the usual Bertha attributes of long lens, usually but not always a telephoto, and rapid focusing. -
Aberration Invariant Optical/Digital Incoherent Optical Systems
Imaging Systems Laboratory, Department of Electrical Engineering University of Colorado, Boulder, Colorado 80309 Aberration Invariant Optical/Digital Incoherent Optical Systems Edward R. Dowski, Jr., W. Thomas Cathey, and Joseph van der Gracht Abstract Control of optical aberrations is a principal objective of any optical design. High performance optical designs with well-corrected aberrations typically have a very low tolerance to fabrication and alignment errors and are composed of very specific optical materials. Such systems are almost always more costly than equivalent systems with less well-corrected aberrations. By optimum combination of optical pre-processing and digital post-processing, or optical coding and digital decoding of the image information, incoherent optical systems invariant to numerous aberrations can be formed. The theory of aberration invariance can also be used with low-cost, low-precision optics to produce systems that image with the performance of high-cost, high-precision, or near diffraction-limited, spatial resolution. We can show that the central aberration to be controlled is second order, or misfocus. Systems that are invariant to misfocus are also invariant to chromatic aberration, astigmatism, thermal effects, and spherical aberration. This paper therefore describes, with experimental evidence, a focus-invariant optical system. Research The most common approach to approximating a focus-invariant imaging system is to stop down the pupil aperture. Although stopping down the aperture does increase the amount of focus invariance, or depth of field, there is an attendant loss in optical power at the image plane, as well as a reduction of the diffraction-limited image resolution. The aperture can be viewed as a simple absorptive mask in the pupil plane of an optical imaging system; however, this absorptive nature results in a loss of light. -
Digital Light Field Photography
DIGITAL LIGHT FIELD PHOTOGRAPHY a dissertation submitted to the department of computer science and the committee on graduate studies of stanford university in partial fulfillment of the requirements for the degree of doctor of philosophy Ren Ng July © Copyright by Ren Ng All Rights Reserved ii IcertifythatIhavereadthisdissertationandthat,inmyopinion,itisfully adequateinscopeandqualityasadissertationforthedegreeofDoctorof Philosophy. Patrick Hanrahan Principal Adviser IcertifythatIhavereadthisdissertationandthat,inmyopinion,itisfully adequateinscopeandqualityasadissertationforthedegreeofDoctorof Philosophy. Marc Levoy IcertifythatIhavereadthisdissertationandthat,inmyopinion,itisfully adequateinscopeandqualityasadissertationforthedegreeofDoctorof Philosophy. Mark Horowitz Approved for the University Committee on Graduate Studies. iii iv Acknowledgments I feel tremendously lucky to have had the opportunity to work with Pat Hanrahan, Marc Levoy and Mark Horowitz on the ideas in this dissertation, and I would like to thank them for their support. Pat instilled in me a love for simulating the flow of light, agreed to take me on as a graduate student, and encouraged me to immerse myself in something I had a passion for.Icouldnothaveaskedforafinermentor.MarcLevoyistheonewhooriginallydrewme to computer graphics, has worked side by side with me at the optical bench, and is vigorously carrying these ideas to new frontiers in light field microscopy. Mark Horowitz inspired me to assemble my camera by sharing his love for dismantling old things and building new ones. I have never met a professor more generous with his time and experience. I am grateful to Brian Wandell and Dwight Nishimura for serving on my orals commit- tee. Dwight has been an unfailing source of encouragement during my time at Stanford. I would like to acknowledge the fine work of the other individuals who have contributed to this camera research. Mathieu Brédif worked closely with me in developing the simulation system, and he implemented the original lens correction software. -
Longitudinal Chromatic Aberration
Longitudinal Chromatic Aberration Red focus Blue focus LCA Transverse Chromatic Aberration Decentered pupil Transverse Chromatic Aberration Chromatic Difference of Refraction Atchison and Smith, JOSA A, 2005 Why is LCA not really a problem? Chromatic Aberration Halos (LCA) Fringes (TCA) www.starizona.com digitaldailydose.wordpress.com Red-Green Duochrome test • If the letters on the red side stand out more, add minus power; if the letters on the green side stand out more, add plus power. • Neutrality is reached when the letters on both backgrounds appear equally distinct. Colligon-Bradley P. J Ophthalmic Nurs Technol. 1992 11(5):220-2. Transverse Chromatic Aberration Lab #7 April 15th Look at a red and blue target through a 1 mm pinhole. Move the pinhole from one edge of the pupil to the other. What happens to the red and blue images? Chromatic Difference of Magnification Chief ray Aperture stop Off axis source Abbe Number • Also known as – Refractive efficiency – nu-value –V-value –constringence Refractive efficiencies for common materials water 55.6 alcohol 60.6 ophthalmic crown glass 58.6 polycarbonate 30.0 dense flint glass 36.6 Highlite glass 31.0 BK7 64.9 Example • Given the following indices of refraction for BK7 glass (nD = 1.519; nF = 1.522; nC = 1.514) what is the refractive efficiency? • What is the chromatic aberration of a 20D thin lens made of BK7 glass? Problem • Design a 10.00 D achromatic doublet using ophthalmic crown glass and dense flint glass Carl Friedrich Gauss 1777-1855 Heinrich Seidel 1842-1906 Approximations to -
Optical Performance Factors
1ch_FundamentalOptics_Final_a.qxd 6/15/2009 2:28 PM Page 1.11 Fundamental Optics www.cvimellesgriot.com Fundamental Optics Performance Factors After paraxial formulas have been used to select values for component focal length(s) and diameter(s), the final step is to select actual lenses. As in any engineering problem, this selection process involves a number of tradeoffs, wavelength l including performance, cost, weight, and environmental factors. The performance of real optical systems is limited by several factors, material 1 including lens aberrations and light diffraction. The magnitude of these index n 1 effects can be calculated with relative ease. Gaussian Beam Optics v Numerous other factors, such as lens manufacturing tolerances and 1 component alignment, impact the performance of an optical system. Although these are not considered explicitly in the following discussion, it should be kept in mind that if calculations indicate that a lens system only just meets the desired performance criteria, in practice it may fall short material 2 v2 of this performance as a result of other factors. In critical applications, index n 2 it is generally better to select a lens whose calculated performance is significantly better than needed. DIFFRACTION Figure 1.14 Refraction of light at a dielectric boundary Diffraction, a natural property of light arising from its wave nature, poses a fundamental limitation on any optical system. Diffraction is always Optical Specifications present, although its effects may be masked if the system has significant aberrations. When an optical system is essentially free from aberrations, its performance is limited solely by diffraction, and it is referred to as diffraction limited. -
Criminalistics & Forensic Physics MODULE No. 27
SUBJECT FORENSIC SCIENCE Paper No. and Title PAPER No.7: Criminalistics & Forensic Physics Module No. and Title MODULE No.27: Photographic Lenses, Filters and Artificial Light Module Tag FSC_P7_M27 FORENSIC SCIENCE PAPER No. 7: Criminalistics & Forensic Physics MODULE No. 27: Photographic Lenses, Filters and Artificial Light TABLE OF CONTENTS 1. Learning Outcomes 2. Introduction- Camera Lenses i) Convex Lens ii) Concave Lens 3. Useful terms of the lens 4. Types of Photographic Lens 5. Defects of Lens 6. Filters for Photography 7. Film Sensitivity 8. Colour of Light 9. Summary FORENSIC SCIENCE PAPER No. 7: Criminalistics & Forensic Physics MODULE No. 27: Photographic Lenses, Filters and Artificial Light 1. Learning Outcomes After studying this module, you shall be able to know – What are Camera Lenses and their types Various terms of the Lens Various types of Filters used in Photography 2. Introduction – Camera Lenses Camera lens is a transparent medium (usually glass) bounded by one or more curved surfaces (spherical, cylindrical or parabolic) all of whose centers are on a common axis. For photographic lens the sides should be of spherical type. A simple or thin lens is a single piece of glass whose axial thickness is less compared to its diameter whereas a compound lens consists of several components or group of components, some of which may comprise of several elements cemented together. Lenses are mainly divided into two types, viz. i) Convex Lens ii) Concave Lens FORENSIC SCIENCE PAPER No. 7: Criminalistics & Forensic Physics MODULE No. 27: Photographic Lenses, Filters and Artificial Light i) Convex lens: This type of lens is thicker at the central portion and thinner at the peripheral portion. -
Numerical Aberrations Compensation and Polarization Imaging in Digital Holographic Microscopy
NUMERICAL ABERRATIONS COMPENSATION AND POLARIZATION IMAGING IN DIGITAL HOLOGRAPHIC MICROSCOPY THÈSE NO 3455 (2006) PRÉSENTÉE À LA FACULTÉ SCIENCES ET TECHNIQUES DE L'INGÉNIEUR Laboratoire d'optique appliquée SECTION DE MICROTECHNIQUE ÉCOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE POUR L'OBTENTION DU GRADE DE DOCTEUR ÈS SCIENCES PAR Tristan COLOMB ingénieur physicien diplômé EPF de nationalité suisse et originaire de Bagnes (VS) acceptée sur proposition du jury: Prof. Ph. Renaud, président du jury Prof. R.P. Salathé, directeur de thèse Prof. C. Depeursinge, rapporteur Prof. M. Gu, rapporteur Prof. H. Tiziani, rapporteur Prof. M. Unser, rapporteur Lausanne, EPFL 2006 En mémoire de Grand-maman, Pierrot et Simon Abstract In this thesis, we describe a method for the numerical reconstruction of the complete wavefront properties from a single digital hologram: the ampli- tude, the phase and the polarization state. For this purpose, we present the principle of digital holographic microscopy (DHM) and the numerical re- construction process which consists of propagating numerically a wavefront from the hologram plane to the reconstruction plane. We then define the different parameters of a Numerical Parametric Lens (NPL) introduced in the reconstruction plane that should be precisely adjusted to achieve a cor- rect reconstruction. We demonstrate that automatic procedures not only allow to adjust these parameters, but in addition, to completely compen- sate for the phase aberrations. The method consists in computing directly from the hologram a NPL defined by standard or Zernike polynomials without prior knowledge of physical setup values (microscope objective fo- cal length, distance between the object and the objective...). This method enables to reconstruct correct and accurate phase distributions, even in the presence of strong and high order aberrations.