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Cyclopedia of Photography

Absorption
Absorption (pr., Absorption; Ger., Absorp Tion) This Term Is Used Both In A Chemical And An Optical Sense. In The Former Sense It Is Used To Designate The Taking Up Of One Substance By Another, Just As D. Sponge Absorbs Or Sucks Up Water. As A Rule, This Is Not ...

Accelerator
Accelerator (pr., Accaorateur ; Ger., Beschleuniger) A Substance Added To Developing Solutions To Shorten The Duration Of Development And Bring Out The Image More Quickly. Usually It Is An Alkali Which Hastens The Development Owing To Its Power Of Absorbing The Bromine Set Free From The Silver Salt During Development, ...

Acetic Acid
Acetic Acid (pr., Acide Acetique ; Ger., Essigsdure) Also Known As Purified Pyroligneous Acid. Molecular Weight, 6o. There Are Three Kinds Of Acetic Acid:—(r) Glacial, Con Taining About 99 Per Cent. Of Acid And R Per Cent. Of Water (sp.g., 1.065) ; Glacial Acetic Acid Is The Most Widely Used ...

Acetone
Acetone (fr., Acetone ; Ger., Aceton) A Colourless Volatile Liquid Of Peculiar And Characteristic Odour, Having The Formula C3 0 Or Co Ch3. It Is Met With Commercially In Various Qualities. It Is Miscible In All Propor Tions With Water, Alcohol, And Ether. As The Vapour Is Highly Inflammable, The ...

Acetylene Generator
Acetylene Generator (fr., Generateur D' Acetylene ; Ger., Acetylengasentwickler) An Apparatus For Generating Acetylene By The Action Of Water On Calcium Carbide. Of The Two Types Of Generators, That Is Probably The Better In Which The Carbide Is Immersed In Or Dropped Into The Water, As When Water Is Permitted ...

Acid Fixing Bath
Acid Fixing Bath The " Hypo '' (hyposulphite Of Soda) Fixing Bath Made Acid. Ordinary " Hypo " Fixing Baths Are Neutral, Not Acid ; But Acid Fixing Baths May Be Used For Negatives And Bromide And Gas Light Prints, Although Not For Prints On Print Out Papers. Their Advantages ...

Actinic Powers Of Artificial
Actinic Powers Of Artificial Lights Standard Candle . . . Colza Lamp, Fin. Wick . . 2 Paraffin Lamp, 4-in. Wick . . 4 „ I-in. Wick . . 10paraffin Duplex Lamp . . 3o 2-ft. Gas Burner . . . 12 5-ft. „• • • 35 I6-c.p. Electric Incandescent ...

Actinometer
Actinometer An Instrument For Gauging The Depth Of Print Ing In Those Processes In Which Little Or No Visible Image Is Produced By Exposure To Light ; Known Also As A Print Meter. There Are Two Types Of Actinometers, Differing Both In Character And In Method Of Using. The Essential ...

Adurol
Adurol (fr. And Ger., A Durol) A Developer Intermediate In Character Between The Short Factor Developers, Such As Pyro And Hydroquiuone, And The Longer Factor Developers Such As Metal, Rodinal, Amidol, Etc. ; Introduced In 1899. It Is A Mono-chlor (or Mono-brow) Hydroquinone. Adurol-hauff Has The Formula Cl(oh And Adurol-schering ...

Aerial Image
Aerial Image (fr., Image Aerienne ; Ger., A Etherisch Bad) A Properly Corrected Lens Produces, As It Were, An Aerial Model At Its Focus Of The Scene At Which It Is Directed. Each Portion Of This Model Is At The Same Relative Distance From Other Portions As Are The Corresponding ...

Aerial Screen
Aerial Screen (pr., Ecran D'air ; Ger., Windschirm) A Form Of Screen For Giving Relief And Other Effects For Optical Lantern Pictures, Its Special Object Being To Arrest The Light Coming From A Lantern And To Reflect It Back To The Point At Which The Projected Image Is To Be ...

Albumen
Albumen (fr., Albumins; Ger., Albumen) A Very Complex Organic Compound Containing Carbon, Hydrogen, Oxygen, And Sulphur, Which Occurs Both In The Animal And Vegetable Kingdom. Animal Albumen Exists As The Serum Or White Fluid Of Blood, But Photographically The White Of Eggs Is The Only Animal Albumen Used. To Prepare ...

Albumen Process
Albumen Process Negatives.—an Old Process Invented By Niepce De St. Victor, In 1848. Glass Was Coated With Albumen Containing Potassium Iodide, And The Film Was Sensitised By Dipping In A Nitrate Of Silver Bath. Many Modifica Tions Followed, But Probably The Process Most Widely Used Was The One Published On ...

Albumen Process Beer
Albumen Process (beer) A Dry Collodion Process For Solar Photography, Introduced By Sir William Abney In 1874, Also Of Use For Landscape Work. Abney's Formula Is : Alcohol (•825) . 41-3 Drms. 270-180 Ccs. Ether • • 3i-5 210-300 „ Pyroxyline7 Grs. 7 G. Ammonium Iodide Z „ 2 Cadmium ...

Alcohol
Alcohol (pr., Alcool ; Ger., Alkohol) Chemically, Alcohols Are Neutral Compounds Formed By The Replacement Of Hydroxyl Oh For One Atom Of Hydrogen In A Saturated Carbon Compound ; For Instance, C,h, Ethylene Gives C,h, Oh Ethyl Hydrate, Or Ordinary Alcohol. They Unite With Acids With Elimination Of Water To ...

Alkalimeter
Alkalimeter (fr. Alcalimetre ; Ger., Alkalimeter) An Instrument For Testing The Amount Of Alkali Present In A Commercial Sample Which May Have An Admixture Of Impurities. It Was Invented By F. A. H. Descroizilles, Of Dieppe, Though Some Have Claimed The Discovery For Dr. Andrew Ure, Of Glasgow. It Consists ...

Alum Hypo Toning
Alum-hypo Toning A Method Of Toning Black-and-white Prints On Bromide And Gaslight Papers To A Sepia Colour, Sometimes Referred To As The " Boiling Process " And As "sulphur Toning" ; Actually It Is A Sulphur Toning Process, But Not The Only One. The Formula For The Bath Is : ...

Aluminium Flashlight
Aluminium Flashlight Aluminium Bronze Powder, Also Known As " Silver Bronze," May Be Used In Place Of, Or In Conjunction With, Magnesium For Flashlight Work. It Is Cheaper Than Magnesium, Burns Under Cer Tain Conditions With Less Smoke, But It Is Not Quite So Actinic. The First Experiments With This ...

Ammonia
Ammonia (pr., Ammoniaque ; Ger., Ammo Niak, Ammoniakwasser, Salmiakgeist) A Volatile, Pungent Gas, Which For Photographic And Many Other Purposes Is Used In The Form Of A Watery Solution ; Formerly Known As " Spirit Of Hartshorn." The Strongest Solu Tion, And That Mostly Used, Is Of •88o Sp. G., ...

Ammonium Persulphate
Ammonium Persulphate (fr., Per Sulfate D'ammoniaque; Ger., Ueberschwe Felsaures Ammonium) Molecular Weight, 228. Solu Bility, T In 2.5 Water. It Takes The Form Of Colourless Crystals, Which Are Obtained By Electro Lysis. It Is Principally Used As A Reducer, And Is Especially Valuable In That It Reduces The High Lights ...

Anamorphoscope
Anamorphoscope (fr., Anarnorphoseope ; Ger., Anamorphoskop) A Cylindrical Convex Mirror For Reflecting The Image Of A Distorted Drawing And Restoring It To Its Proper Proportions. Concave Or Convex Mirrors Distort Images In A Singular Manner, And Produce Very Interesting Effects. Anamorphoses Constitute Particular Objects Belonging Especially To The Lass Of ...

Anastatic Process
Anastatic Process (fr., La Photo Graphie Anastatique ; Ger., Anastatisch Druck) A Method Of Copying Line Drawings By Placing A Sensitive Material With Its Film Side In Contact With The Drawings, And Exposing To Light Through The Back Of The Sensitive Paper Or Plate. This Process, Originally Invented By J. ...

Anastatic Process Of Lithography
Anastatic Process Of Lithography A Process Of Lithography By Which Prints, Particularly Old Ones, May Be Treated So As To Yield A Transfer, Which May Be Inked Up And Printed From. The Essential Features Of The Pro Cess Are That The Ink Of The Print Is Softened And Made Transferable ...

Anthotype
Anthotype An Obsolete " Nature Printing " Process In Vented By Sir John Herschel And Founded Upon The Sensitiveness Of Juices Of Plants. Chevreul And Hunt Also Experimented In The Same Direc Tion. The Expressed Juices, And Alcoholic Or Watery Infusions Of Certain Flowers, More Par Ticularly Papaver Rhceas And ...

Antimony Process
Antimony Process (fr., Photographie L'antimoine ; Ger., Spiessglas-druck) A Printing Process Discovered By Francis Jones, Of The Manchester Grammar School, In 1876. When The Gas Stibine, Or Antimonietted Hydrogen Is Passed Through A Glass Tube Containing Sulphur, In The Presence Of Sunlight, A Decomposition Takes Place, Resulting In The Formation ...

Apertometer
Apertometer (pr., Ouverture Mare ; Ger., Oeflnungmesser) An Instrument For Measuring The Numerical Aperture Of A Lens Or Objective. Of Those Forms Used In Photomicrography, The Best Was Devised By Abbe, Consisting Of A Semicircular Glass Plate With The Various Apertures Figured On The Outer Edge. The Straight Edge Of ...

Aphengescope
Aphengescope (fr., Megascope, Aphenge Scope ; Ger., Aphengeskop, Wunderkamera Fur Undurchsichtige) In The Aphengescope Or Opaque Lantern, Also Sometimes Called The Megascope, The Images Are Projected Upon The Screen By Reflection Instead Of By Transmitting The Light Through Transpar Encies. The First Magic Lantern Of This Nature Appears To Have ...

Arabin
Arabin Gum•bichromate Process A Gum-bichromate Printing Process, Worked Out By Nelson K. Cherril, And Published In June, 19°9. To Prepare The Arabin, A Quantity Of Best Soudan Gum Arabic Is Sifted Through A 40-mesh Sieve. Place In A Quart Earthenware Jar 15o Ccs. Of Water, 7 Ccs. Of Pure Hydrochloric ...

Arc Lamps
Arc Lamps (fr., Lampes D Arc ; Ger., Bogen Larnpen) Lamps In Which A Powerful Light Is Obtained By Passing An Electric Current Through A Pair Of Slightly Separated Carbon Pencils. Where The Current Is Interrupted By The Gap An Intensely Brilliant Arc Is Created. Arc Lamps Are Of Two ...

Architectural Photography
Architectural Photography In Photographing Architectural Subjects, Whether For Pictorial Or Record Purposes, Regard Must Be Paid To The Fact That Technical Correct Ness Is Absolutely Essential. Many Technical Points That Can Be Ignored Without Any Serious Disadvantage In Landscapes Become Important In Architecture, And Disregarding Them Would Involve Serious Loss ...

Artigue Process
Artigue Process A Modification Of The Carbon Process, Named After Its Inventor, Mons. Artigue. No Safe Edge Is Necessary On The Negative, There Is No Transfer, And Consequently The Print Is Not Reversed. The Paper For This Process Is Sup Plied Coated With A Mixture Of A Colloid Sub Stance ...

Artograph
Artograph An Automatic Machine, Known Also As The Electric Artograph And Telautograph, For Sending Sketches Or Line Drawings Along A Telegraph Wire, Invented About R89r By N. S. Amstutz, Of Cleve Land, Ohio. According To A Description Published At The Time, The Picture Was Photographed On A " Stripping Film ...

Asphaltum
Asphaltum (fr., Asphalte, Bitume De Judge ; Ger., Asphalt, Judenpech) Synonyms, Asphalt, Bitumen, Bitumen Of Judea, Mineral Pitch, And Jew's Pitch. A Natural Product Of The Decomposition Of Vege Table Substances. The Term Asphaltum Comes From The Greek Word For Fossil Pitch, Harrtpakros (and •cintaxoitat) And Signifies An Unchangeable Body. ...

Autochrome Process
Autochrome Process A Process Of Screen-plate Colour Photography Invented By Mm. Ere [eng. Pat. 22,077, 1904 ; 25,718, 1904 ; 9100, 'goo], Based On The Use Of Starch Grains, As Far As Possible Of A Uniform Size, Dyed To The Necessary Colours, Red, Green And Blue Violet, Mixed And Sifted ...

Automatic Photography
Automatic Photography (pr., La Photographie Automatique ; Ger., Auto Matische Photographie) A Term Frequently Applied Loosely, And Refer Ring Strictly Only To Apparatus That Carries Out The Entire Operation Of Making A Finished Photo Graph. To This Class Belongs The Automatic Machine Exhibited By M. Enjalbert At The Paris Exhibition ...

Average Portraits
" Average " Portraits A Style Of Picture Made By Taking Several Portraits Of The Same Size Upon One Plate, Or By Printing From Several Portrait Negatives Upon One Piece Of Paper, The Result Being Sup Posed To Give A Type Of The Whole. Such Pic Tures Are Claimed By ...

Background
Background (fr., Fond ; Ger., Hinter Grund) A Term Commonly Applied To The Painted Sheets Or Screens Used In Studio Portraiture ; But Actually The Scenery, Or Anything Else, Whether These. It Is A Common Fact That Many Portraits Are Spoilt By Ugly And Unsuitable Backgrounds, But It Is Possible ...

Backgrounds
Backgrounds, The Art Of Using Two Or More Negatives To Form One Print Has Been Widely Practised For Many Years. It Is Sometimes Referred To As Double Printing And As Combination Printing, But The Former Term Is Generally Understood To Mean The Printing-in Of Clouds (which See), And The Latter ...

Baryta Paper
Baryta Paper (pr., Papier Baryte ; Ger. Barytpapier, Kreidepapier) Good Raw Paper Stock Coated With An Insoluble Emulsion Of Baryta In Gelatine And Used Princi Pally For Coating Paper Intended To Take A Gela Tino-chloride Emulsion. A Good Baryta Paper Must Be Coated With Three Films, The First Two Serving ...

Bas Reliefs
Bas-reliefs Plaster Or Wax Casts In Low Relief Produced From Photographs ; Formerly They Were Popular For Brooches, Cameos, Etc. Generally, The Relief Obtained Is Very Small. The Process Depends Primarily Upon The Hardening Action Of Light Upon Gelatine Impregnated With Potassium Bichromate. A Negative Should Be Specially Taken For ...

Bennetts Toning Bath For
Bennett's Toning Bath For P.o.p. A Combined Toning And Fixing Bath That Gives Rich Purple Tones On Most Brands Of P.o.p., Introduced In 1908 By H. W. Bennett. It Con Tains A Sufficiently Large Proportion Of " Hypo " To Ensure Perfect Fixation Of The Prints, And The Bath Is ...

Bichromate Lamp
Bichromate Lamp A Lamp For Dark-room Use In Which A Solution Of Potassium Bichromate Serves As The Light Filter. Howard Farmer Found That The Various Kinds Of Ruby And Orange Fabrics And Glass In Common Use Transmit Only 2 Per Cent. Or Less Of The Light, Whereas A 6 Per ...

Bichromated Gelatine
Gelatine, Bichromated Gelatine Treated With An Alkaline Bichromate Forms The Basis Of The Carbon Process And Of All Photo-mechanical Printing Methods. Fish-glue Is Employed In Some Processes, But That Is A Sub Stance Closely Allied To Gelatine ; And Other Colloids Are Sometimes Substituted, As In The Gum-bichromate Process. Gelatine, ...

Blackening Apparatus
Blackening Apparatus Only A Dead Black Is Suitable For The Interior Of A Camera, As A Glossy Black Would Give Rise To Reflections. Blackings Should Be Tested Upon Pieces Of Metal, Wood, Leather, Etc., Before Applying To The Apparatus. Recipes Are As Follow : Brasswork.—to Blacken Camera Brasswork, Clean With ...

Blisters
Blisters Blisters Appear At Times Upon All Makes Of Plates, Films, And Papers In The Manufacture Of Which Albumen Or Gelatine Is Employed, But The Papers Most Subject To The Trouble Are Albumen And Bromide. The Principal Cause Of Blisters Is The Use Of A Too Strong "hypo" Bath, Rapid ...

Bottles
Bottles (fr., Bouteilles, Flacons ; Ger., Flaschen) Narrow-mouthed Bottles A Are Best For Liquids, And Wide-mouthed Ones, B And C, For Solids. Those With Flat-topped Stoppers Are Preferable, It Being Then Less Easy For Dust To Collect In The Space Between The Neck And The Stopper. A Useful And Neat ...

British Gum
British Gum (see " Dextrine.") Broken Negatives These Must Not Be Confused With Cracked Negatives (which See), As They Are Not Treated In The Same Way. Broken Negatives Are Generally Understood To Be Those In Which The Film Is Broken As Well As The Glass. If The Glass Only Is ...

Bromide Process
Bromide Process The Essential Feature Of The Bromide Process Is Its Suitability For Obtaining Either Contact Prints Or Direct Enlargements By Artificial Light, And The Consequent Facilities That It Gives For Secur Ing Any Desired Result With Absolute Certainty. If A Print Is Produced Which Is Not Exactly In Accordance ...

Bromoil Process
Bromoil Process A Process Of Obtaining Pictures By Bleaching And Pigmenting Bromide Prints ; Suggested By E. J. Wall In 1907. Working Details Were First Published By C. Welborne Piper In August Of The Same Year, And The Modified Process, As Now Worked, Was Introduced In The Following Month. Prints ...

Brush Development
Brush Development The Development Of Negatives, Bromide Prints And Platinum Prints By Applying A Suitable Developer By Means Of A Brush Instead Of Immers Ing In The Developer. For Negatives The Slower Working Developers, Such As Pyro, Are More Suit Able Than The Rapid Kinds, Such As Rodinal, Metol, Etc. ...

Brush Toning
Brush Toning A Method Of Toning In Which The Solution Is Applied By Means Of A Brush. This Method Is Occasionally Adopted For Large Prints. A Con Centrated Solution Is Employed And The Print, After Washing, Is Laid On A Sheet Of Glass And The Solution Rapidly Brushed Over Its ...

Bubbles On Plates And
Bubbles On Plates And Papers Bubbles Or Air-bells Frequently Form On Plates And Papers During Development, And They Have The Effect Of Preventing The Developer Acting On The Spots Covered By Them. The Result Is Clear Glass Spots Upon The Negative Or White Spots Upon Developed Prints. Bubbles Invariably Arise ...

Burnisher
Burnisher (fr., Pressed Satiner A Chaud ; Ger., Heisssatinirmaschine) A Machine For Imparting A Glossy Surface To Prints By Pressure And Friction Against A Heated And Polished Bar Or Roller. The Bar Burnisher A —the Older Type—has A Polished Steel Or Nickelled Must Be Avoided. The Prints Should Not Be ...

Calculating Distances In
Calculating Distances In The Rule For Finding Distances When Reducing Is : Divide The Longer Base Of The Image To Be Reduced By The Longer Base Of Copy Desired, Which Will Give The Number Of Times Of Reduction ; To This Add I And Multiply By The Focal Length Of ...

Camera
Camera (fr., Chambre, Chambre Noire ; Ger., Kamera) The Photographic Camera Is Essentially A Light Tight Box, Having A Lens At One End And Provided At The Other With A Suitable Arrangement For The Insertion And Withdrawal Of The Sensitive Plate Or Film. To Ensure That The Required Amount Of ...

Camera Obscura
Camera Obscura (fr., Chambre Obscure ; Ger., Die Dunhelltammer) Literally, " Dark Chamber " ; An Optical Instrument Invented By Baptista Porta In 1569, Although There Is Evidence Of An Even Earlier Knowledge Of Its Principle And Properties. This Simple Instrument Depends In Principle On The Fact That If A ...

Camera Stand
Camera Stand (pr., Pied ; Ger., Static) A Raised Support For The Camera, To Keep It Steady During Focusing And Exposure. There Are Several Varieties, Differing In Construction Accord Ing To Their Purpose. In The Older But Still Very Common Form Of Studio Camera Stand B The Top Is Raised ...

Camera On Cycle
Cycle, Camera On There Are Many Opinions As To Which Is The Best Plan Of Carrying A Camera On A Cycle, Much Depending Upon The Size Of Camera And Amount Of Apparatus It Is Desired To Carry. Many Of The Pocket And Folding Cameras Need Not Be Considered, As They ...

Camera_2
Camera (pr., Chambre A Ail De Poisson ; Ger., Fischenauge-hamera) J. Alan Stewart, M.a., Has Published A Method Of Obtaining Photographs Resembling The Views That Would Be Seen By The Eye Of A Fish. Objects Against The Light Of The Sky Are Only Perceived By The Fish When They Fall ...

Candle Balance
Candle Balance (fr., Balance D Chandelle ; Ger., Kerzenwage) An Instrument Employed In Photometry To Ascertain The Loss Of Weight Undergone By A Candle After Burning A Given Time. Lighting Effects In A Photograph, Apparently Due To The Use Of A Candle As The Illuminant. Actually The Candle Pictured Plays ...

Carbon Process
Carbon Process The Idea Of The Carbon Process As It Is Known To-day Is Credited To A. I,. Poitevin, Who, In D. Patent Dated December 13, I855, Describes The Action Of Light Upon A Chromated Gelatine Mixed With D Pigment. J. Pouncy Is Supposed To Have Been The First Actually ...

Carbon Transfer Papers
Carbon Transfer Papers Transfer Papers For Receiving The Film Or Image In The Carbon Printing Process. Two Kinds Of Such Paper Are Used, Called Respectively " Single Transfer Paper " And " Double Transfer Paper." The Former Are Those Employed When The Film Or Image Is Transferred From Its Original ...

Caricature
Caricature (fr., Caricature ; Ger., Zerrbild, Karthatur) A Freak Portrait Obtained By Using Special Backgrounds And Foregrounds, Distorting The Film, Copying, Etc. Some Of The Methods Of Producing Caricatures Are Described Below, And Others Will Be Found Under Such Definite Headings As " Doubles " And " Trick Photography." Large ...

Catatype
Catatype (fr. And Ger., Catatypie) A Process Depending On Catalytic Action, Which Is Defined In The Preceding Article. In The Original Catatype Process Patented By Messrs. Ostwald & Gros In I9oi, A Negative Image Consisting Either Of Silver Or Platinum Is Immersed In A Solution Of Hydrogen Peroxide In Ether, ...

Catechu Toning
Catechu Toning A Method Of Toning Prints On Platinum Paper To Various Shades Of Brown By Means Of A Solution Of Catechu Was Introduced By J. Packham In 1895. The Stock Toning Solution Is Made Up As Follows : Place I2o Grs. Of Catechu In 5 Oz. Of Water And ...

Causes Of Fading
Fading, Causes Of All Silver Images, Whether Negative Or Positive, Are Formed By Metallic Silver In An Extremely Fine State Of Division Imbedded In A Vehicle Of Albumen, Gelatine, Or Collodion. Everyone Knows How Prone Silver, Even In The Form Of Spoons And Forks Or Ornaments, Is To Tarnish, And ...

Centring Of Lenses
Centring Of Lenses When A Lens Is Correctly Centred The Axes Of All Its Surfaces Are In A Straight Line ; Otherwise, Good Definition Cannot Be Obtained. Faulty Centring Gives A Distortion To The Image Similar To That Of Astigmatism Or Coma, And Is Easily Detected By Fixing The Lens ...

Ceramic Process
Ceramic Process The Art Of Obtaining A Burnt-in Impression Of A Photograph On Earthenware, China, Or Porcelain. Such Pictures Are Permanent Because The Image, Formed By A Vitrifiable Powder, Is Protected By An Imperishable Glaze. The Material Of Which The Picture Is Composed Must Obviously Be Of A Special Nature. ...

Certinal
Certinal A Highly Concentrated Liquid Developer In One Solution Form, Introduced By Ilford Ltd., March, 1909. The Best Proportion For Developing Plates And Films Which Have Received Normal Exposure Is Certinal 24 Drops, Water I Oz. At A Tempera Ture Of 6o° F. (nearly 16° C.) The Image Appears In ...

Changing Bags And Boxes
Changing Bags And Boxes A Changing Bag Is A Device To Allow Of Reload Ing Dark-slides Or Sheaths Without The Necessity For A Dark-room. It Is Generally A Bag Of Several Thicknesses Of Black And Red Material, Provided With Sleeves Which Tighten Round The Arms By Means Of Elastic, So ...

Chemical Retouching
Retouching, Chemical (fr., Retouche Chimique ; Ger., Chemische Retouchier) Modifying Or Removing Portions Of A Photo Graph, Usually In The Negative, By Means Of Chemical Solutions Applied With A Brush. Thus In Developing, Any Details That Come Up Too Rapidly May Be Kept Back By Draining The Nega Tive And ...

Chromatic Aberration
Chromatic Aberration (pr., Aber Ration Chromatique ; Ger., Chromatische Abweichung) To Arrive At A Proper Understanding Of The Cause Of Chromatic Aberration, It Is Necessary To Remember That A Lens Is Practically A Prism With The Power Of Refracting Or Altering The Direction Of Rays Of Light And, In An ...

Chronometric Shutter
Chronometric Shutter (pr., Obtura Teur Chronometrique ; Ger., Chronometrischer Verschluss) A Shutter Mechanically Geared To Give A Pre Cisely Timed Exposure, Or Successive Exposures At Accurately Recurring Intervals. The Art Of Making Photographic Records Of The Motion Of An Object In Chronological Order. In The Year 187o, Prof. E. J. ...

Chrysotype
Chrysotype An Obsolete Process Analogous To The Blue Print Process, Invented By Sir John Herschel In 1842 ; Known Also As " Chripotype." It Can Be Best Described In The Inventor's Own Words : " Paper Is Washed With A Moderately Strong Solution Of Ammonia-citrate Of Iron, And Dried. The ...

Circle Of Least Confusion
Circle Of Least Confusion The Theoretically Perfect Lens Is Capable Of Sharply Reproducing A Point Or A Line, No Matter How Small Or Fine. In Telescope And Microscope Objectives, Where Only Rays Near The Axis Of The Lens Are Used, This Condition Is Nearly Fulfilled, But In Photographic Lenses, Where ...

Cleaning Bottles
Cleaning Bottles The Methods Employed For Cleaning Bottles Will Depend Upon What The Bottles Have Contained. The Simple And Old-fashioned Method Of Half Filling The Bottle With Water And Adding Sand, Cinders, Or Shot May Serve In Some Cases, As May The Use Of A Little Vinegar And Broken-up Egg-shell. ...

Cleaning Dishes
Cleaning Dishes Dishes Used For " Hypo " Should Not Be Put To Other Photographic Purposes, Even After Clean Ing, As Any Print Treated Therein Is Liable To Be Stained. Dishes Used For Developing And Toning Soon Become Dirty, Particularly When The De Veloper Oxidises Quickly, As Pyro, For Example. ...

Cleaning Glass
Glass, Cleaning Glass For Photographic Purposes Must Be Scrupulously Dean. Glass Upon Which Prints Are Squeegeed For Glazing Is Best Cleaned By Soaking In Very Dilute Nitric Acid And Scrubbing With Soap And Water ; After Drying, It Is Dusted Over With French Chalk And Polished. When Glasses Are To ...

Cleaning Lenses
Cleaning Lenses It Is Easy To Damage A Lens By Improper Cleaning, Optical Glass Being Generally Much Softer Than Other Kinds. Apart From Actual Scratches The Surface Is Liable To Become Dulled, A Condition That Affects The " Rapidity." The Necessity For Frequent Cleaning Is Obviated By Fitting All Lenses ...

Cleaning Negatives
Cleaning Negatives The Films Of Negatives Are Best Cleaned When Wet. Usually They Are Merely Wiped Over With A Piece Of Wet Cotton-wool ; But To Remove A Dirty Or Messy Appearance From A Dry Negative Use Cotton-wool Soaked In Methylated Spirit, Rubbing Very Lightly To Avoid Reducing The Den ...

Cleaning And Restoring Daguerreotypes
Daguerreotypes, Cleaning And Restoring Cleaning And Restoring A Daguerreotype Picture Is At All Times A Risky Process, And Should Not Be Attempted Unless The Worker Is Particularly Careful And Patient. Many Methods Have Been Advocated, But They All Need Care And Thought, And Rather Than Run The Risk Of Ruining ...

Cloud Negatives
Cloud Negatives Clouds That Are To Be Added To Landscapes Must Be Taken Under Similar Conditions To Those Of The Landscapes For Which They Are Required. A Large Common Or Open Space Should Be Selected For Photographing, So That A Low Horizon Line May Be Included On The Plate. And ...

Coating
Coating It Will Be Found Somewhat Easy With A Little Practice To Coat Plates If The Operation Is Prac Tised First In Daylight Or Gaslight, And For This Purpose It Is Advisable To Start With Whole Plates, Assuming That One Wishes Subsequently To Obtain Quarter Plates. A Pneumatic Holder (which ...

Cockling Of Prints
Cockling Of Prints Photographs Mounted In A Wet State Upon Thin Cardboard, Or Upon The Leaves Of An Album, Invariably Cockle Or Curl When Dry, Whereas Prints Mounted Surface-dry Do Not Cockle So Badly. The Defect Is Clue To Uneven Expansion Caused By The Wet Mountant, And Can Be Made ...

Collodion
Collodion (fr., Collodion ; Ger., Kollodium) A Solution Of Pyroxyline In A Mixture Of Equal Quantities Of Alcohol And Ether ; It Should Be Kept In A Well-stoppered Bottle. It Is A Colour Less, Syrupy Liquid, Being More Or Less Fluid According To The Quantity And Nature Of The Pyroxline ...

Collodion Emulsion
Collodion Emulsion A Suspension Of Various Silver Salts In Collo Dion, And Used For Printing-out Papers, Trans Parencies By Development, And Negative Work. The Simplest Of All Collodion Emulsions To Make Is That For Printing-out Paper, Or, As It Is Some Times Called, Collodio-chloride Paper. There Are Numerous But Those ...

Colloids
Colloids A Name Derived From Greek Kolla (glue) And Eidos (appearance), And Given By Graham To Those Non-crystalline Substances Which Do Not Diffuse Through Porous Membranes. The Chief Organic Colloids Are Cellulose, Starch, Dextrine, Tannin, Gelatine, Caramel, And Albumen. The Inorganic Colloids Are Hydrated Oxides Of Iron, Hydrated Silica, Alumina, ...

Collotype
Collotype (fr., Phototypie ; Ger., Licht Druch) A Process Known Also As " Phototype," And, In Slight Variations, As " Albertype," " Arto Type," Etc. It Is Based On The Principle That If A Film Of Bichromated Gelatine Is Exposed To Light Under A Negative, And The Unaltered Bichromate Is ...

Colour Absorption
Colour Absorption Whilst Colour Itself Is An Absorption Of Light (see " Colour "), It Is Extremely Important In Some Cases To Know The Colours Absorbed By Certain Materials, Such As Aniline Dyes For Filter Making. The Only Method Of Determining This Satisfactorily Is By Means Of A Spectroscope, Or, ...

Colour Screen Or Filter
Colour Screen Or Filter A Sheet Of Coloured Glass, Or Glass Coated With Dyed Gelatine Or Collodion, Or A Cell Containing A Coloured Liquid, Used To Modify The Action Of Some Particular Region Of The Spectrum On The Sensitive Plate. It Is Usual To Divide Colour Screens Into Two Classes, ...

Colour Sensations
Colour Sensations Although There Are Considered To Be But Six Or Seven Spectrum Colours—red, Orange, Yellow, Green, Blue, Indigo, And Violet—they Melt So Insensibly One Into The Other That There Are An Infinite Number Of Distinct Colours ; Again, In Natural Objects There Are Innumerable Colours. It Has Been Proved, ...

Colour Sensitising
Colour Sensitising It Was Very Early Recognised That Certain Colours Acted More Strongly On The Photographic Plate Than Others, And That The Former Were Nearly All Those That Reflected The Violet And Blue Spectral Rays, Which Therefore Were Called The " Chemically Active " Or " Actinic," Whilst Green, Yellow, ...

And Depth Of Focus
Field, And Depth Of Focus "depth Of Field" Is Sometimes Used As Synony Mous With " Depth Of Focus " And " Depth Of Definition," The Third Expression More Correctly Indicating What Is Meant. Theoretically, Objects On Different Planes, However Small Their Separa Tion, Are Brought To A Focus By ...