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A Perfect Negative
A Perfect Negative The Authors Defined "a Technically Perfect Negative As One In Which The Opacities Of Its Gradations Are Proportional To The Light Reflected By Those Parts Of The Original Object Which They Represent," And Their Research Showed That Such A Relation May Exist But Only When A Plate ...

A Practical Analysis Of
A Practical Analysis Of Subjects It Has Undoubtedly Occurred To Many Readers That The Classification Of White And Black And The Different Colors As To Their Inherent Actinicities Is A Refinement Seldom Necessary In Practice. The Purpose Has Been To Establish In The Mind Of The Reader A True Conception ...

Actinism And Diaphragm Systems
Actinism And Diaphragm Systems In Order To Apply Rudimentary Knowledge To The Practice Of Photography It Is Necessary To Develop In The Mind The Idea Of A Value Not Be Fore Met With That Of Actinicity. This Is De Fined As The Capability Of Radiation To Produce Certain Chemical ...

An Exposure Recompense
An Exposure Recompense In Photographing Near Objects The Lens Rests Further From The Plate Or Film Than It Does When Focused On A Distant Object. For Example, Should A Lens Of 16 Cm. Focus Be 2 Cm. In Diam Eter Its Convergence Will Be F/8 When Focused On A Distant ...

Classification Of Subjects
Classification Of Subjects Exteriors: Clouds With Sun Directly Beyond Them As For Obtaining The So-called Moonlight Effects 2m Average Clouds In Sunlight Not In Above Position . . , 512 New Snow 256 Bird's Eye, Mid-distance, Marine And Old Snow Views 128 White Subjects, Foreground And Otherwise 128 Average Exterior ...

Comparison Of Different Actinicities
Comparison Of Different Actinicities We Have But To Observe At Any Time That Which Confronts Our Eyes To Comprehend That The Field Of Vision Is Filled With A Miscellaneous Assortment Of Objects And That The Nearest Ones Outline Their Edges Against The Surfaces Of Those Next Beyond Them, Etc. One ...

Derivation Of The Unit
Derivation Of The 'unit Cone Referring Now To The Spherical Cone In Which The Diameter Of The Base Equals The Altitude, It Follows That It Might Be Described As Being Equivalent To A Relative Aperture Of F/ 1, And As Every Point Of The Surfaces About Us In Nature Is ...

Intensification
Intensification Intensifier: 12 Grams Bichloride Of Mercury Dissolved In 400 C.c. Of Water 15 " Iodide Of Potassium " " 40 " " " 24 " Hyposulphite Of Soda " " 60 " " " Or: 1/2 Ounce Bichloride Of Mercury Dissolved In 20 Ounces Of Wad 5 Drachms Iodide ...

Law Of Constant Density
Law Of Constant Density Ratios An Important Part Of The Work Of Hurter And Driffield Was The Experimental Demonstration Of The Statement Made In The Last Paragraph, Viz., That The Ratio Of The Densities Of Any Two Areas Of A Finished Negative Is Independent Of Development. A Plate Was Exposed ...

Measurement Of Opacity
Measurement Of Opacity Hurter And Driffield Define Opacity As "the Optical Property Of A Substance To Impede The Passage Of Light Through It." On This Definition The Author Of The Present Work Suggests The Following Practical Method For Measuring And Defining That Property. In The Sense Of The Def Inition ...

Negative Making
Negative Making Photography Be Practised As Taught In The Method Herein Presented, Le. With Due Consideration To The Actinicity Of The Sur Faces Photographed And With A Knowledge Of The Inertia Exposure To Be Given In Each Case, It May Easily Be Realized That Development Is Almost Purely Mechanical In ...

Plane And Solid Angles
Plane And Solid Angles If Two Mutually Perpendicular Lines Be Drawn Through The Center Of A Circle, Four Right Angles Are Formed, Each Subtended By One Quarter Of The Circumference. Again, Each Of These Quad Rants May Be Halved Or Further Subdivided At Will. If Now Three Planes Mutually Perpendicular ...

Problems In Unit Actinometry
Problems In Unit Actinometry To Find The Actinicity Of Any Surface Of Known Average Diameter And Known Distance From The Tinting Medium, T.e., Of Known Cone Value. To Illustrate This Problem Suppose That The Average Actinicity Of A Common Kerosene Flame Is Desired. Measure Or Estimate The Average Diameter Of ...

Reduction
Reduction The Negatives Being Thoroughly Fixed May Be Lifted From The Fixing Bath, Rinsed Once And Ex Amined On The Above Device To See If There Are Any Which Require Reducing Locally Or Entirely. If A Negative Be Found Too Dense Throughout It Should Be Dipped Once More In Water ...

Reduction And Intensification
Reduction And Intensification These Operations Have Heretofore Usually Been Performed On Negatives Which Have Been Pre Viously Dried And Perhaps Printed From. This Practice Is Wrong. Negatives Should Never Be Dried Without First Being Brought To The Desired Contrast. In The Present Method The Work Of Re Duction Or Intensification ...

Still Another Optional Method
Still Another Optional Method The Foreground And Other Subjects Referred To In The Preceeding Paragraphs Are Of The Nature Of "open Views" Or Those Whose Planes Recede Into The Mid Distance And Beyond. There Is Another Distinct Class Of Foreground Subjects Which It Is Necessary To Notice Since Their Actinicity ...

Subjects Of Minimum Contrast
Subjects Of Minimum Contrast Views Are Usually Of This Class As Well As Flat Surfaced Subjects Which Have But Little Tone Or Color Gradation And Hence Little Actinic Contrast, As For Example The Evenly Toned Tin Type Or Ferrotype, The Daguerreotype And Also Photographs Which Have Little Tone Contrast And ...

Subjects Of Normal Contrast
Subjects Of Normal Contrast A Subject Under This Head Is Defined As One Whose Actinic Contrast Does Not Differ Greatly From 1 To 32, And An Emulsion Of Equal Latitude Will Of Course Be Normal For Such A Subject And With Normal Exposure The Full Scale Of Tones Will Be ...

Subjects Of Over Normal Actinic
Subjects Of Over-normal Actinic Contrast The Extreme Subject Of This Class Is Usually A Combination Of Interior And Exterior As Il Lustrated By The Example Of The Cloud And The Window Casing On Page 93. Such Subjects Should Be Avoided When Possible. If The Con Trast Is Not Too Abnormally ...

The Character Of Sunlight
The Character Of Sunlight With Clear Sky When The Sky Is Clear The Actinicity Of Sunlight Depends Almost Wholly On The Sun's Position With Regard To The Horizon. Many Exposure Tables Give The Exposures For Certain Latitudes And The Different Months And Hours Of The Day, But The Combination Of ...

The Characteristic Curve
The Characteristic Curve The Above Proposition Was Experimentally Demonstrated In The Following Way. Thickly Coated Slow Plates Were Found Best For Experi Ment. Upon One Of These A Series Of Exposures Was Made Beginning With One Second And Doub Ling The Time At Each Successive Exposure. The Times Of Exposure ...

The Element Of Time
The Element Of Time This Is One Of The Basic Factors In The Study Of Actinometry And In The Practice Of Photography. As A Child The Writer Believed The Duration Of A Second To Be Inconceivably Short And It Is Certain That Children Generally Have A Very Abstract Idea Of ...

The F System
The F System It Can Easily Be Demonstrated That If A Circle Be Drawn On The Surface Of Any Sphere Equal In Area To One Half Of One Of Its Octants Above Re Ferred To, The Diameter Of This Circle Will Equal Approximately The Radius Of The Sphere And There ...

The Ii S Or
The Ii. S. Or Uniform System It Will Be Necessary Here To Give An Explana Tion Of The Uniform System For Numbering Diaphragms For The Reason That This Method Is The One Now In Use On The Majority Of Double Lenses In The United States, Where, Until Recently, Lens Makers ...

The Latitude Of Emulsions
The Latitude Of Emulsions The Latitude Of An Emulsion Is Its Capacity To Render In Perfect Gradation Different Degrees Of Actinicity In The Same Subject. An Emulsion Is Said To Have Great Latitude When It Will Register Greatly Differing Intensities And To Be "hard" On Contrasty When It Will Register ...

The Least Visible Tint
The Least Visible Tint And The First Appearance Time The Least Visible Tint Is The Faintest Spot Which It Is Possible To Distinguish On Any Tinting Med Ium On Exposing It To Light Behind An Opaque Screen In Which A Hole Has Been Cut (p. 35). The Tint Is Observed ...

The Method As Practised
The Method As Practised The Foregoing Method Of Reducing The Actin Icity And Diaphragm To Unity Has Been Given To Make Clear In A Simple Manner The Theory Involved In Measuring The Speed Of An Emul Sion. In "speeding An Emulsion" In Practice, However, It Is Unnecessary Either To Alter ...

The Relation Of Actinic
The Relation Of Actinic Gradation To The Tone Steps Of The Picture It Is Necessary Now To Illustrate The Effect Of The Different Actinic Planes Of A Subject On The Opacity Steps Of The Negative As Brought About By Different Degrees Of Exposure. Let A, B, C, D, And E ...

The Special Need Of
The Special Need Of Unit Diaphragm Numbers On Seeing The F As Well As The Unit System Employed In The Problems In The Following Chap Ter, Some Reader May Justly Ask Why The Author Should Find The Former So Unfit For The Number Ing Of Lens Stops. This Has Been ...

The Speed Of Emulsions
The Speed Of Emulsions It Is A Fact That In Their Daily Practice Many Photographers Use Developing Formulas Much Stronger Than What Might Be Considered Normal, I.e., Stronger Than Would Be Required For Purely Normal Exposures. The Chapter On Develop Ment Should Be Read (p. 120) Before Performing The Following ...

The Speed Of Plates
The Speed Of Plates And Films A Speed List, If Incorporated In This Book, Would Soon Be Out Of Date, Since New Plates And Films Are Continually Appearing On The Market. In Chapter 5 It Has Been Made Clear That Each Exposure In Practice Is Really A Test And Proof ...

The Standard Tinting Medium
The Standard Tinting Medium Many Speeds Of Dry Plates And Films Are Made, I.e., Many Degrees Of Latent Sensitiveness, But The Author Has Found That The Rate With Which These Emulsions Visibly Discolor On Exposure To Light Is Practically The Same In All And For This Reason All Ordinary Dry ...

The Unit Diaphragm Scale
The Unit Diaphragm Scale This Diaphragm Scale Is Different From All Others In That It Is A Geometrical Series Of Cone Values Starting With That Of F/ 64 As Unity. These Diaphragms Therefore Do A Certain Work In More Or Less Time As There Are A Lesser Or Greater Number ...

Tinting Mediums Other Than
Tinting Mediums Other Than The Standard It Has Been Seen That In Order To Measure The Actinicity Of The Sky With The Standard Film Emulsion In The Standard Meter The Time Re Quired To Get The Standard Tint Is Inconveniently Short. It Is Also True That The Great Sensitiveness And ...

Unit Actinometry
Unit Actinometry For Practical Use These Conditions May Be Secured In The Following Manner. Procure A Small Pocket Note-book With A Tough, Flexible Paper Cover And A Small, Shallow Pasteboard Box Either Square Or Circu Lar And Not Over A Half Inch In Depth, Such As May Be Found In ...