Applied Photographic Optics

Transcription

1 Applied Photographic Optics Lenses and optical systems for photography, film, video and electronic imaging Second edition Sidney F. Ray BSc, MSc, FBIPP, FMPA, FRPS Focal Press

2 Acknowledgements Abbreviations 1 Introduction The role of the lens in photography.1 Imaging. Recording.3 Measurement.4 Extension of visual perception.5 Self-expression 3 Optical requirements Optical theory 4 Light and energy 4.1 Dual nature of light 4. Wave nature 4.3 The electromagnetic spectrum The full spectral range 4.3. The visible spectrum Spectral power distribution Particle nature Photometry Effect on detectors 5 Properties of light 5.1 Transmission Transmittance Colour transmission Optical transmission density Optical path length Absorption 5..1 Absorption law 5.. Spectrally selective absorption 5..3 Heat filters 5..4 Black filters Reflection Laws of reflection Types of reflection Laser speckle Reflection from dielectric surfaces Reflection from metal surfaces XV xvi Refraction Laws of refraction 5.4. Total internal reflection Snell's window Displacement Deviation Scratch treatment Double refraction Graded refractive index Dispersion Scattering Particle size Interference Diffraction Wavelength dependence Dispersion by diffraction Conditions for interference Producing interference Newton's rings Fringe visibility Fraunhofer diffraction The diffraction grating The zone plate Spatial filtering 5.9 Polarization Natural light 5.9. Polarized light and polarizers Elliptically polarized light Circularly polarized light 5.10 Attenuation Inverse square law of illumination Lambert's cosine law Image formation by simple optical systems Types of image The pinhole Simple lenses Definitions 6.3. Focal length Simple mirrors Plane mirrors 6.4. Spherical mirrors Aspherical mirrors Image characteristics Orientation 6.5. Shape Magnification

3 6.6 Image construction by graphical methods 6.7 Image properties by calculation Sign convention 6.7. Lens conjugate equation Newton's equation Lagrange invariant 6.8 Imaging limitations Image formation by compound lenses Cardinal planes Rear nodal point The thick lens Formulae 7.3. Single-element types Thick lens combinations Thin -layer coatings Light emitting diodes (LEDs) Charge coupled devices (CCDs) Light losses by surface reflections Single anti-reflection layers Double anti-reflection layers Multiple anti-reflection layers Mirror coatings Metal substrate Dielectric substrate Dielectric filters Dichroic filters Gradient index filters Coating methods Combinations of elements Thin lens combinations Effective focal length 8.1. Back focal length and back focal distance Separation of elements Specific combinations 8..1 Positive-positive systems 8.. Positive-negative systems 8..3 Negative-positive systems 8..4 Varifocal system Telescopes The compound microscope Field flatteners Relay systems Optical components and their imaging roles Lenses Spherical lenses 9.1. Aspherical lenses Mirrors 9..1 Curved mirrors 9.. Plane mirrors Beamsplitters Optical flats Cylindrical lenses Lenticular devices Prisms Fresnel lenses and mirrors Optical fibres Step index fibres 9.9. Graded index fibres, rods and lenses Holographic optical elements Diffractive optical elements Micro lenses Opto-electronic devices Liquid crystal displays (LCDs) Aberrations defects in imaging systems 11.1 Image formation The perfect lens Failure of paraxial optics Monochromatic aberrations 11. Surface contributions Transverse ray aberrations 11.. Wavefront aberrations Aberration terms Seidel aberration coefficients Ray aberrations as Seidel sums Other methods 11.3 Spherical aberration Thin lens imagery Aspheric surfaces Floating elements Portrait lenses Additional aberration 11.4 Coma 11.5 Astigmatism 11.6 Field curvature Petzval curvature Film flatness Field flatteners Curved field lenses 11.7 Distortion Types Measurement Calibrated focal length 11.8 Fundamental lens designs 11.9 Aberrations of other systems Hologram Electronic imaging systems 1 Optical materials 1.1 Glasses

4 vii Origins and composition 1.1. Manufacturing methods Properties Special glasses 1. Plastics 1..1 Types 1.. Properties 1..3 Hybrid systems 1..4 Constructional plastics 1.3 Other materials Polarizing and filter materials 1.3. Natural and synthetic quartz Fluorite and crystals Germanium and others Colour correction of lenses Chromatic errors Transverse chromatic aberration Achromatic combinations Conventional glasses Anomalous dispersion Apochromatic lenses Superachromatic lenses Monochromatic lenses Reflective systems UV and IR photography The speed of a lens Stops, pupils and windows Exposure Field stop Aperture stop Pupils Pupil magnification Entrance window Aperture Relative aperture 14.. Aperture calibration Effective aperture Numerical aperture Transmission aperture Photometry of image formation Theoretical principles Cos 4 в law of illumination Image illuminance in wide-angle lenses Camera exposure Vignetting Optical vignetting Mechanical vignetting Graduated neutral density filters Lens covering power Lens and camera flare 15.1 Flare effects Veiling glare Types and sources of flare Measurement of flare Instrumental methods 15.. Ghost images Reduction of flare Lens and camera design Lens hood systems Applications of flare 16 Resolving power of lenses and imaging systems Resolving power The diffraction-limited lens Resolving power criteria 16.. Practical limits The aberration-limited lens Resolving power capabilities Photographic resolving power Silver halide systems Video imaging tubes and devices Measurement of resolving power Test targets Target optical contrast Area weighted average resolution 17 Physical optics of lens systems Image formation Spread functions Convolution Modulation Fourier transform techniques Fourier transforms 17.. The OTF OTF analysis Variables Spatial frequency The MTF Cascading Graphical presentation Applications of MTF Lens design and testing Imaging systems Coherent optics Abbe's theory Fourier transform plane Spatial filtering 18 Design, manufacture and testing of a lens Lens design Computer aided design Stages of production Special fabrication techniques

5 Diamond machining Electroforming Replication Aspherics Lens-testing routines Workshop testing Batch testing MTF testing routines Determination of lens parameters Contrast measurements and criteria MTF measurement apparatus 164 Evaluation and calibration Focusing an optical system The need for testing Infinity tests The collimator The autocollimator Star testing Resolution testing Lens-testing charts Test target design The Sayce chart Testing by projection Camera lenses Video diascope projector Slide projectors and enlargers Cine projectors Test charts for video systems Field testing Camera calibration Principal point location Principal distance Laboratory methods MTF testing Sharp focus Photographic space 0.1. Image sharpness Geometry of focusing Mechanical arrangements Fixed focus 0.3. Symbol focusing Unit focusing Optical methods Supplementary lenses 0.4. Front cell focusing Internal focusing Close focusing Photographic focusing Focusing with non-visible radiations 0.6. Photographic focus calibration Image sharpness meter Autofocus and focus maintenance methods Operational needs Autofocus enlargers Cam systems Inverter systems Slide projection Autofocus cameras Ranging systems Image contrast measurement Exit pupil measurements Autofocus by phase detection Phase detection Principles The autofocus module Detector arrays Autofocus flash assist Additional AF functions 196 Depth of field and depth of focus 00.1 Depth of field parameters Sharpness Visual acuity Circle of confusion 01. Depth of field equations 0..1 Derivation of equations 0.. Distribution of depth of field 05.3 Depth of field in practice Departures from theory Hyperfocal distance Estimating depth of field Variable field curvature 07.4 Close-up depth of field Equations Background sharpness Immersion techniques Holographic techniques 08.5 Depth of focus Equations Relationship to depth of field Practical considerations Image surface considerations Electron microscopy 10.6 Use of movements 11.7 Depth of field scales and calculators Scales 1.7. Calculators DOF calculators for large format cameras 13.8 Special techniques Aerial image relay system Multi-plane scanning Confocal microscopy 15

6 ix 3 Perspective and projection Concepts of perspective Viewpoint 3.1. Camera viewpoint Viewing distance Perspective distortions Wide-angle perspective Portrait lens perspective Perspective of tilted planes Other perspectives Orthographic perspective 3.5. Panoramic perspective Projection formulae Lens types and properties 4 Evolution of the photographic lens Introduction Prephotography Optical instruments 4.. Optical glass 4..3 Lens manufacture 4..4 Lens design 4..5 The camera obscura 4..6 The Chevalier Landscape lens 4..7 Systematic design of lenses The first camera lenses Optics of the Daguerreotype camera 4.3. Wolcott mirror camera Astigmatic lenses Colour correction 4.4. Achromatic doublets Orthoscopic lenses The Petzval lens The astigmatic lens Anastigmatic lenses The first anastigmats 4.5. Symmetrical anastigmats The Cooke triplet Meniscus anastigmats Other types of lenses 17 6 The standard lens Standard focal length 6. Lens designs 6.3 Lens limitations 7 Large-aperture lenses 7.1 Maximum aperture limits 7. Aperture requirements 7.3 Design features Standard lenses 7.3. Wide-angle lenses Long focus lenses Catadioptric lenses Image intensifier optics 8 Medium long focus lenses 8.1 Lens parameters 8. Design types 8.3 Focusing 9 Extreme long focus lenses 9.1 Lens parameters 9. Resolving power 9.3 Lens design 9.4 Practical considerations 30 The telephoto lens 30.1 The telephoto principle 30. Design evolution Early designs 30.. Distortion-free designs Modern designs 30.3 Super telephoto designs 31 Convertible lenses 31.1 Design principles 31. Design variants Dual focal length 31.. Interchangeable components Other possibilities General properties of a lens 5.1 Optical properties Focal length 5.1. Aperture Field of view Format Performance 5. Mechanical properties 5..1 Configuration data 5.. The lens barrel 5..3 The lens mount 5..4 Flange focal distance 5..5 The iris diaphragm 5.3 Cleaning lens surfaces Short focus wide-angle lenses 3.1 Imaging characteristics Field of view 3.1. Covering power Distortion Back focal distance 3. Lens designs 33 Retrofocus wide-angle lenses 33.1 The retrofocus principle Early designs Simple optics Distortion

7 x Contents ЪЪ Lens designs Configurations 33.. Close focusing 34 The fisheye lens 34.1 Imaging requirements 34. Design development 34.3 Design features Catoptric systems.1 Mirror optics.1.1 Imaging properties.1. Single-mirror systems.1.3 Dual-mirror systems. Contemporary designs 36 Catadioptric systems Improvements to mirror systems Schmidt corrector Mangin mirror Bouwers-Maksutov system Unusual designs Design features Imaging characteristics Aperture Focusing 37 Zoom lenses 37.1 Design principles The zoom concept Two-element systems The afocal zoom variator The relay system The compensator Focusing element Historical development Design features Aberration correction Variable maximum aperture Zoom ratios and ranges Integration of a viewfinder Ergonomics Focusing arrangements Normal range Close focusing range Compact zoom lenses Enlarging lenses 38.1 Imaging requirements 38. Resolving power 38.3 Image illumination 38.4 Enlarging calculations 38.5 Features of lenses 38.6 Enlarging lens designs Macro lenses 39.1 Terminology 39. Imaging requirements 39.3 Optimum aperture 39.4 Macro lens designs 39.5 Medical macro lenses 39.6 True macro lenses 40 Process lenses 40.1 Imaging requirements Process cameras Aberration correction Field of view Resolving power and contrast 40. Lens designs Configurations 40.. The iris diaphragm Reversing prisms 41 Copying lenses 41.1 Imaging requirements Field topography Subject features 41. Lens design Aperture 41.. Other features 41.3 Contemporary designs Electrophotography CRT displays Relay systems Cine copying Camera lenses 4 High-resolution lenses 4.1 Resolving power requirements Micro-imaging 4.1. Theoretical capabilities 4. Constraints on optical designs 4..1 Imaging geometry 4.. Chromatic correction 4..3 Depth of focus 4.3 Lens designs Micro-imaging lenses 4.3. Microdocumentation lenses Optical disc lenses 43 Underwater lenses 43.1 Environmental considerations 43. Refraction effects Field of view 43.. Distortion 43.3 Corrective systems Dome port Ivanoff corrector Retrofocus systems 43.4 Water contact lenses

8 xi Aerial lenses 44.1 Environmental considerations 44. Lens designs Hand-held cameras 44.. Reconnaissance lenses Survey lenses Projection lenses.1 Imaging requirements.1.1 Magnification.1. Field of view.1.3 Curvature of field.1.4 Image orientation.1.5 Image properties. Image photometry.3 Depth of focus.4 Lens types.4.1 Simple and triplet lenses.4. Petzval lens.4.3 Double Gauss lens.4.4 Telephoto and retrofocus.4.5 Varifocal and zoom lenses.4.6 PC lenses.5 Lens attachments.5.1 Zoom attachments.5. Anamorphic attachments.6 Video projection lenses Anamorphic systems 46.1 Optical requirements 46. Optical design principles Crossed slits 46.. Cylindrical systems Prismatic systems Mirror systems 46.3 Anamorphics in practice Soft focus lenses 47.1 Imaging requirements 47. Soft focus methods Conventional lenses 47.. Perforated diaphragm plates Floating elements Perspective control lenses 48.1 Imaging requirements 48. Tilt and shift lenses 48.3 Mechanical arrangements 48.4 PC projection lenses Ultraviolet lenses 49.1 Spectral considerations Spectral transmission Chromatic correction 49. Contemporary designs Catoptric systems 49.. Dioptric systems i Infra-red lenses Spectral considerations Imaging regions Optical materials Contemporary designs Conventional lenses 50.. IR corrected lenses Thermal imaging lenses 51 Lenses for cinematography Video lenses Formats Design requirements Operational requirements 8 mm cine lenses 16 mm and mm cine lenses Large aperture lenses Wide-angle lenses Zoom and anamorphic lenses Video imaging Optical performance Design requirements Mechanical arrangements 5.3. Colour correction Lens types Zoom lenses 5.4. Conventional lenses Special purpose lenses Lens attachments 53 Lens attachments and accessories V 53.6 Afocal converters Principles Telescopic devices Applications Teleconverter devices Principles 53.. Performance Attachment of optical systems Microscopes Other devices Supplementary lenses Positive (close-up) lenses Negative lenses Optical filters Spectral properties Filter factor Optical quality Filter sizes Focusing Filter applications Image modification devices Direction sensitive devices Image degradation devices

9 xii Contents 53.7 Reflecting systems Beamsplitters 408 Photographic optical systems 54 Viewfinder systems Viewfinder functions 54. Human vision Anatomy 54.. Refraction Resolving power Dark adaptation X Flicker 54.3 Viewfinder properties Magnification Image orientation Aberrations 54.4 Viewfinder errors Aiming errors Parallax error 54.5 Interactive viewfinders 55 Direct viewfinder systems The frame finder The brilliant finder The Newton finder The reversed Galilean finder The van Albada 55.6 The universal finder finder The zoom finder The Kepler finder The universal range-viewfinder The director's viewfinder Viewfinders for autofocus compact cameras Screen viewfinder systems The focusing screen Screen properties Screen variants The screen image The focusing magnifier 56. Reflex systems Image properties The reflex mirror 56.3 The pentaprism viewfinder The viewfinder eyepiece Optical principles The focusing telescope Eyepiece dioptric correction Video viewfinders Viewfinder focusing The human factor Simple focusing systems / 415 ^ Focusing by estimation Stadiametric rangefinders Optical coincidence rangefinders Principles Coupled rangefinder Rangefinder accuracy 57.4 Screen focusing Focusing accuracy Contrast characteristics Special focusing techniques Passive focusing aids The split-image rangefinder Microprism arrays 444 The optics of camera movements Degrees of freedom View camera design Translation movements Rotation movements Lens covering power Extra covering power Displacement limits Control of image sharpness Tilts and swings Limits The Scheimpflug rule or condition Yaw-free movements Control of image shape 5 59 Optics of systems with moving film Intermittent motion Framing rate Image quality Limitations Continuous motion Image motion compensation The strip camera The streak camera The periphery camera The panoramic camera } 59.3 Rotating prism compensators Image displacement 46 v/ Practical systems 46 1\59A Image stabilization Camera shake Stabilizing systems Scanning optics Scanning systems Mechanical scanning Rotating mirror systems Nipkov disc system Airborne scanners Film scanning Laser scanning Polygon scanners Scanning lenses Dot generation 473

10 хш Optics of close-up photography and photomacrography Magnification and subject area Optical systems Focusing extension 61.. Lens reversal Close-up lenses Teleconverter devices Other lenses Framing and focusing Perspective and working distance Depth of field Illumination systems Exposure considerations Opti< :s of copying systems 6.1 Copying requirements Subject matter 6.1. Reproduction ratio Fidelity Exposure 6. Illumination of the original 6..1 Avoidance of reflexes 6.. Distribution of illumination 6.3 Sizing and alignment Accurate size images 6.3. Alignment Framing Focusing Depth of field Optics of printing systems Fundamentals Magnification Printing density 63. Illumination systems Illuminants Diffuser arrangements Condenser arrangements Design features Negative carrier Filters Printing equipment Enlargers Printers Movie optical printers Exposure assessment systems Rectification printing Camera tilt Enlarger easel tilt Combined tilts Full correction Rectification in practice 50 Optics of projection systems The scope of projection Choice of lens Image illumination Self-luminous objects Illuminated opaque objects Trans-illuminated objects Projection systems The episcope The epidiascope The overhead projector The slide projector The 8 mm cine projector The 16 mm cine projector The mm cine projector Projection screens General requirements Optical performance Screen types Rear projection Screen properties Image orientation Video screen viewing Backgrounds by front axial projection Imaging geometry Screen properties Video projection Imaging requirements Single lens projection Triple lens projection Light valve systems 519 Optics of stereoscopic systems Visual perception of space Depth cues Stereoscopic ability Stereoscopic photography Basic requirements 65.. Image parallax Stereo window Transposition 65.3 Orthostereoscopy Necessary conditions Shape distortion Choice of base Stereo projection Theoretical considerations Image depth control Stereoscopic systems Cameras Cine cameras Mirror stereoscopes Lens stereoscopes Stereo projection Anaglyphs Autostereoscopic systems Stereophotomicrography Optics of light metering systems Calibration 538

11 xiv Contents Light meters The photodetector 66.. Acceptance angle Spot meters Optical attachments Incident light measurements In-camera metering systems Photocell location Photocell optics Segmented photocells OTF measurements Optics of lighting systems Lighting Attributes Illumination Lighting ratio Shadows Artificial sources Daylight Lumin aires Spotlights Floodlights Fibre optic systems Electronic flash Optics of flash units Red eye effects Flash guide number 68 Optics for video systems Optii cs of holography Index Video cameras The colour splitter The three-chip camera Aliasing Spatial offset Filter arrays Optical multiplexing Telecine Video disc Outline theory Wavefront reconstruction Mathematical outline Fringe patterns Hologram properties Holographic techniques Illumination system 69.. Recording requirements