المعالجة والطباعة بالأبيض والأسود .. المرشد خطوة بخطوة للتصوير الفوتوغرافي

المعالجة والطباعة بالأبيض والأسود .. المرشد خطوة بخطوة للتصوير الفوتوغرافي

BLACK AND WHITE PROCESSING AND PRINTING

STEP 1 : Processing film
STEP 2 : Printing from negatives
STEP 3 : Enlarging
STEP 4 : Manipulated printing

You can take good photographs without doing your own processing and printing . Some of the photographers features in the Evolving Your Own Approach section ( see pp . 177-202 ) send all their exposed film to a reliable laboratory . Others consider their composition as only half complete when taken from the camera , and often manipulate the result extensively during printing . Therefore , you may wish to pass over this section and move on to more advanced camera work or color photography . But even if you do not intend to start processing and printing your own films , reading this section will show you the effects of over- and underexposure and of faulty printing , and will help you to identify and eliminate them from your work .

The main advantage of processing and printing yourself is that you can control the final picture in various ways . You can be as creative in the darkroom as you were with the camera . By the end of this section you should be able to turn the picture originally seen in the camera viewfinder into a good , straightforward , black and white enlargement . All the basic items of equipment you will need are shown , and step - by - step sequences will guide you through each stage . The Steps in the section are intended to be worked through in order and you should complete each one before passing on . It may help to start by re - reading the basic points on light - sensitive materials discussed on pages 18-19 .

Get into the habit of making careful notes of the processing time required for your particular combination of film type and developer before you start . Keep your notes of times and temperatures and printing exposure details along with your results . This is always useful when you are just beginning so that you can learn from your mistakes . Details of procedure may differ slightly according to the make of equipment you buy , but the general sequence of operations applies to almost all films and papers , and can be followed with the book open beside you .

Organization of the section

There are two quite different parts to the section ; developing your film to form black and white negatives , and making contact prints and enlargements on to paper . Film processing is really quite simple . You don't need a darkroom , because the job is carried out in normal lighting with the film in a small light - proof tank . The tank takes a minute or so to load in a light - tight closet or a black fabric changing bag . Apart from the tank you need a few simple items , in particular a clock , a thermometer and some containers for the processing solutions . Processing takes about 40 minutes not including drying time . From the processed negatives you can judge if your images are sharp , correctly exposed , and well framed .

The next stage , printing , really does require access to a darkroom - either your own , or one run by a college or club . The best way to see if you will enjoy this side of photography is to watch someone more experienced actually making prints . Reading through the stages from page 75 will explain what is involved . Two darkrooms are shown on page 74 , one is an ideal , permanent room ; the other is a closet , temporarily converted for darkroom work . Most people begin with this second , smaller room . If you decide to do your own printing , you can control the size and quality of each print individually and , after the initial outlay on equipment , you will be able to get your prints faster and more cheaply than if you sent them to a commercial service .

There are a number of important factors to consider when you set up a temporary or permanent darkroom . Dust must be kept to a minimum so ideally you should choose an area for your darkroom with smooth , plastered walls , and not uncovered brickwork which collects dust . If possible , remove any obvious dust traps , like unnecessary shelves and other wall fixtures . Extreme care must be taken to make door frames , windows , and even ventilation grills light - tight . This usually means that you must provide supplementary air conditioning that is light - proof , if you intend to spend long periods in your darkroom . You will need several electric power outlets and , ideally , a supply of running water . It is advisable to lay chemical - resistant flooring to guard against the spillage of corrosive liquids .

The effort involved in establishing a permanent darkroom demands good planning . You will see on page 74 that you should divide the room into " dry " and " wet " areas , separating liquid processing from the electrical equipment used for enlarging and drying . When you install lighting , ensure that the normal white light switch is within easy reach , so that there is no trouble in finding it in the dark . A wall - mounted safelight should be positioned over the developing tray so that you can watch the development . To prevent any chance of unintentionally exposing light - sensitive materials , you must put the safelight the recommended distance above the tray ( see the manufacturer's instructions ) . A light or some other device outside the darkroom , to show when it is in use , is also important . This prevents people from accidentally opening the door while you are working , and spoiling your work .

Film processing

Most early photography was done using light - sensitive materials which had to be processed immediately . Photographers struggled out with darkroom tents and chests of chemicals , as well as a large plate camera . Often pictures were taken close to streams and lakes which provided water for mixing the solutions . Sheets of glass had to be coated with a sticky material called collodion which contained the light - sensitive silver halide crystals . Silver halides are compounds ( salts ) of silver and the various halogens bromine , iodine , chlorine , and flourine . These salts produce tiny grains of metallic silver on exposure to light . The prepared plate was exposed in the camera and then processed while still wet . -

Using glass as a support for the light - sensitive layer obviously has disadvantages . It is heavy and only practicable with large camera formats . Plastic ( or cellulose ) triacetate has proved to be the most versatile and useful of film bases . It is light and flexible enough to be wound on to spools for easier camera loading and wind - on , and it is cheaper to produce than glass . The back of modern film has a dark appearance before processing , as the base is coated on its non - emulsion side with an " anti - halation " dye . This prevents light reflecting off the base , back into the light- sensitive layer where would form halos around highlights .

About one hundred years ago collodion was replaced by gelatin , as a better way of binding a layer of silver halides to a suitable base . Photographic gelatin has so many advantages as a binder that it has not been improved on since . A toughened version of the gelatin used for jello , it swells when placed in liquid , allowing processing chemicals to enter and react with the silver halides it contains . When dry the gelatin coating returns to normal thickness , without distorting the shape or position of the image . So it is ideal for the wet processing techniques used with modern photographic chemicals .

When untreated silver halide crystals are bound to the gelatin medium , the resulting emulsion is only sensitive to blue and ultra - violet light . The color sensitivity of the crystals can be extended by dyeing them . First advances with dye sensitizing produced " orthochromatic " emulsions . This meant that the emulsion was capable of recording naturally occurring colors in tone values of the same brightness as they appear to the eye . In practice , orthochromatic emulsions are sensitive to the blue and green regions of the spectrum , but are insensitive to reds and oranges . Dye sensitizing for the full range of colors is a more recent development - most modern photographic emulsions have this facility and are termed " panchromatic " .
It takes a relatively long time for light to change enough silver halide grains into metallic silver to form a visible image . So in the camera , an invisible , latent image is formed . Only relatively few atoms of the emulsion are affected by the initial exposure in the camera . These can later be amplified millions of times , by development using developing chemicals which increase the amount of silver in those areas of the image affected by light .

The three processing chemicals you need - developer , stop bath , and fixer- are usually solutions which you simply have to dilute with water . They are cheaper if you buy them as ready- weighed packets of powders which you dissolve in water before use . You can also make up your own solutions from the basic chemicals , shown on page 213 ; this is cheapest of all . There are several types of developer available ( see p . 125 ) . To start off , it is probably best to buy or make up a fine grain general purpose developer such as Kodak D76 , any stop bath ( you can use a water rinse instead ) , and an acid fixer .

Film is extremely sensitive so you must be careful not to scratch or to handle the picture area of the film particularly when it is wet or only partly dry . At this time it is very easy to damage or contaminate the film surface with dust and grit .

Most photographic processing chemicals deteriorate when in contact with air so you must store them in a stoppered bottles of the right size to be completely filled by the solution . This means keeping a number of different size bottles , or using one of the concertina types which can be pushed down to expel air from the container . Use plastic graduates to measure out exact amounts of each chemical for the film you are processing .

Film developer is the most expensive of the chemicals . Some types are re - usable and these work out cheaper , but you have to slightly increase development time with each successive processing , as recommended by the manufacturers . Keep a record of how many films you have developed with your developer . After acting on the film , both stop bath and fixer can be returned to their storage bottles for re - use . About two pints of stop bath or fixer will serve about thirty 35mm films .

A minority of people are allergic to some chemicals used in developers , and these can cause a skin rash . Fixing solutions will make any cuts or scratches on your hands sting . For these reasons you will see that rubber gloves are shown along with the other processing equipment . When processing color material you must wear a pair of these gloves for protection , but they are not essential for black and white work and most photographers do not use them .

Processing exposed film forms negative images , in which the original subject tones are reversed . In the enlarger , the dark and light tones of the negative control the amount of light which reaches the light - sensitive photographic paper ( bromide paper ) . Dark parts of the negative , which represent the brightest parts of the subject , stop the light , and vice versa . When processed , the print will be palest in those areas on the negative which received most light darkest in those areas which received least light , producing a positive image .

Portable wet - plate viewing tent
Early photographers had to carry around cumbersome equipment for the messy wet - plate process . The portable viewing tent , left , was used for inspecting the wet plates in the dark immediately after exposure - so that a further exposure could be made if results were unsatisfactory .

Travelling photographic van
Roger Fenton , the first English war photographer , used this converted van , left , as a travelling darkroom in the Crimean War in the 1850s . The cumbersome van was an easy target as he moved around the battlefields . taking photographs for the Illustrated London News .

Printing

We look first at contact printing , which means making positive prints the same size as the negative , on photographic paper . At one time , when everyone used large format cameras , all prints were made this way because no enlargement was needed from the large negative . Today , you have to enlarge the much smaller negatives to obtain a print of a reasonable size . Sheets of contact prints taken from complete films are a very useful record of each picture you take . From these sheets you can decide which pictures you want to enlarge , and you can analyze any exposure , framing , or processing and printing errors . You don't need an enlarger for contact printing - the exposure can be made with any low wattage desk lamp which gives even lighting .

As with film , your exposed print also has to be processed . To process prints , you use three print - sized trays for the developer . stop - bath , and fixer . Buy a print developer , such as Kodak D163 : or use a " universal " developer - which can be used for film or prints and dilute it for prints . The stop bath and fixer can be the same types used for films , but you often have to alter the dilution . so check the manufacturer's instructions .

For contact printing , you require a " normal contrast " grade paper - perhaps with a white smooth glossy finish - 10 x 8 ins in size . Contrast refers to the number of grays given between black and white . Hard contrast papers give a few grays , soft contrast papers give many more tones of gray . As soon as you start making enlargements , from a range of negatives , you will want several contrast grades - soft and hard grades as well as normal contrast . Soft and hard grade papers give normal contrast prints from harsh and low contrast negatives respectively , as shown on pages 84-5 . You can also buy variable contrast paper , with which , by using color filters over the enlarging lens , you can produce any contrast grade - locally or overall ( see p.87 ) . You may decide to do all your printing on " resin - coated " ( plastic- based ) paper . This processes , washes , and dries faster than the older . fiber - based papers . But it is more expensive and the final print is slightly more difficult to mount and retouch ( see p.88 ) .

After contact printing , we move on to making enlargements . The enlarger you buy for black and white printing can be quite simple , provided it evenly illuminates the negative and has a good quality lens . Even if you have a high quality camera lens . fine detail on the negative will be lost on the print if your enlarger lens is poor . When buying an enlarger look ahead to the possibility of using it for color printing , too . If it has a filter drawer or , better still , a dial - in color head then you can easily use it for color printing ( see p.165 ) .

Enlarging allows you several controls over the image . You can print the negative at almost any size , and also crop ( omit ) any parts of the image ( at the edges ) you wish to leave out . This is a common practice among photographers , and is a simple way of eliminating framing errors ( see p.83 ) or strengthening an image . You can determine how light or dark the print will appear , by your choice of exposure time . You can make a local area of the print lighter by blocking out the light ( " shading " , or " dodging " ) during part of the exposure ; or darker ( " printing - in " ) by giving it an additional period of time . There is no limit to the number of identical prints you can make from one negative . You can go back to old negatives printed by the store and see if you can improve on their results . You can even make black and white prints from color negatives to create special effects ( see p.172 ) . None of these controls will make a good picture out of a technically inadequate or uninteresting negative , but you can make a good image much stronger and more effective by sympathetic printing . For example , image contrast can be increased to add drama , or reduced to give a softer effect .

Doing your own black and white processing and printing is a logical extension of taking your own exposure readings and controlling the camera image , because you will come to know what results you can , and cannot . produce . With experience . merely looking at a negative will give you a good idea of the sort of print quality to expect . What you learn in this section , for black and white photography , is essential information if you are considering doing your own color processing and printing . Color processes are longer , and more decisions are involved in judging color prints , but you follow similar basic procedures .