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الخطوة 4: الفيلم وقياس التعرض / الفيلم .. تقنية الكاميرا .. المرشد خطوة بخطوة للتصوير الفوتوغرافي
STEP 4 : FILM AND MEASURING EXPOSURE / Film
Exposure - the amount of light that is allowed to act on the film - is controlled by the aperture and shutter settings . In order to set the correct exposure on your camera , you need to know the light - sensitivity of your film , and the brightness of your subject lighting and tone ) . On this page , we look at factors involved in choosing film ; the follow ing pages deal with ways of measuring light and calculating the exposure .
Film size and speed :
First you must select the right size film to fit your camera : some cameras take drop - in cartridges , 110 or 126 size ( see p . 26 ) , others take larger rollfilm ( see p . 204 ) , but the most popular size for direct vision and single lens reflex cameras is 35 mm wide and is packaged in a metal cassette . Cassettes contain enough film for either 20 or 36 exposures , with each frame 36 x 24 mm .
The next important factor when choosing a film is its sensitivity , or " speed " , which is given by its ASA ( American Standards Association ) or DIN number . DIN numbers are used mainly in Europe , but most film packs give both ratings .
A film marked 400 ASA is twice as sensi- tive , or fast , as a 200 ASA film ; doubling the ASA number doubles the speed . The faster the film the less exposure you need to give , but the coarser and more " grainy " your picture will appear . This is because a
fast film gains its sensitivity by using larger . grains of silver , so the resulting negatives have a coarse granular pattern that can be clearly seen in enlargements .
To decide on a speed of film you have to consider the lighting conditions and subject matter of your pictures . Films of 64 , 32 or lower ASA numbers are slow and have a very fine grain . They are a good choice if you ! want high quality , grain - free enlargements with lots of detail , but because of their slow- ness the lighting generally must be quite bright . A slow film is also useful if you need to give long exposures for blur effects with- out overexposing .
Films of around 125 ASA still have a fine grain and are more generally applicable . They are ideal for average subjects outdoors and well - lit indoor subjects . Faster films of 400-800 ASA begin to show grain but are sensitive enough for a wide range of sub- jects , inside and outside . Ultra - fast films of 1000 ASA and above are intended for quite dim lighting , or if you deliberately want to produce a grainy picture , or whenever you want to freeze fast action while using fast shutter speeds .
The best general advice is to keep to one brand and one speed such as 125 ASA or 400 ASA film for all your regular photography , and really get used to it . Then change only for unusual subjects or to achieve particular effects .
Negatives and positives :
Nearly all black and white films give a negative record of the image so that light areas of the subject are dark , while dark parts of the subject appear as clear film . Print- ing from this on to photographic paper ( see pp . 74-7 ) again re- verses the tones to create a posi- tive picture . As many prints as you want can be taken ( and en- larged ) from each negative .
Film speed and grain :
The picture above , left , was photo- graphed on 32 ASA film . Even though the negative is shown here enlarged six times , the grain pat- tern is almost unnoticeable . The other picture , right , was exposed on 1250 ASA film . At the same en- largement this much faster film shows a distinct granular pattern . Notice how the grain shows up clearly in mid - gray areas . It tends to break up fine detail , but can give a textured effect which suits some subjects .
Decoding the pack :
The most important pieces of information on the film pack are the film speed ( shown in both ASA and DIN numbers ) , film size ( this pack contains 35 mm film ) , number of exposures ( 20 or 36 , on 35 mm film ) , and whether the film is color or black and white . You should decide these before you buy film . Other information in- cludes the brand name and type and the expiry date for the film . To obtain maximum life from un- exposed film you should store it in a cool , dry place .
STEP 4 : FILM AND MEASURING EXPOSURE / Film
Exposure - the amount of light that is allowed to act on the film - is controlled by the aperture and shutter settings . In order to set the correct exposure on your camera , you need to know the light - sensitivity of your film , and the brightness of your subject lighting and tone ) . On this page , we look at factors involved in choosing film ; the follow ing pages deal with ways of measuring light and calculating the exposure .
Film size and speed :
First you must select the right size film to fit your camera : some cameras take drop - in cartridges , 110 or 126 size ( see p . 26 ) , others take larger rollfilm ( see p . 204 ) , but the most popular size for direct vision and single lens reflex cameras is 35 mm wide and is packaged in a metal cassette . Cassettes contain enough film for either 20 or 36 exposures , with each frame 36 x 24 mm .
The next important factor when choosing a film is its sensitivity , or " speed " , which is given by its ASA ( American Standards Association ) or DIN number . DIN numbers are used mainly in Europe , but most film packs give both ratings .
A film marked 400 ASA is twice as sensi- tive , or fast , as a 200 ASA film ; doubling the ASA number doubles the speed . The faster the film the less exposure you need to give , but the coarser and more " grainy " your picture will appear . This is because a
fast film gains its sensitivity by using larger . grains of silver , so the resulting negatives have a coarse granular pattern that can be clearly seen in enlargements .
To decide on a speed of film you have to consider the lighting conditions and subject matter of your pictures . Films of 64 , 32 or lower ASA numbers are slow and have a very fine grain . They are a good choice if you ! want high quality , grain - free enlargements with lots of detail , but because of their slow- ness the lighting generally must be quite bright . A slow film is also useful if you need to give long exposures for blur effects with- out overexposing .
Films of around 125 ASA still have a fine grain and are more generally applicable . They are ideal for average subjects outdoors and well - lit indoor subjects . Faster films of 400-800 ASA begin to show grain but are sensitive enough for a wide range of sub- jects , inside and outside . Ultra - fast films of 1000 ASA and above are intended for quite dim lighting , or if you deliberately want to produce a grainy picture , or whenever you want to freeze fast action while using fast shutter speeds .
The best general advice is to keep to one brand and one speed such as 125 ASA or 400 ASA film for all your regular photography , and really get used to it . Then change only for unusual subjects or to achieve particular effects .
Negatives and positives :
Nearly all black and white films give a negative record of the image so that light areas of the subject are dark , while dark parts of the subject appear as clear film . Print- ing from this on to photographic paper ( see pp . 74-7 ) again re- verses the tones to create a posi- tive picture . As many prints as you want can be taken ( and en- larged ) from each negative .
Film speed and grain :
The picture above , left , was photo- graphed on 32 ASA film . Even though the negative is shown here enlarged six times , the grain pat- tern is almost unnoticeable . The other picture , right , was exposed on 1250 ASA film . At the same en- largement this much faster film shows a distinct granular pattern . Notice how the grain shows up clearly in mid - gray areas . It tends to break up fine detail , but can give a textured effect which suits some subjects .
Decoding the pack :
The most important pieces of information on the film pack are the film speed ( shown in both ASA and DIN numbers ) , film size ( this pack contains 35 mm film ) , number of exposures ( 20 or 36 , on 35 mm film ) , and whether the film is color or black and white . You should decide these before you buy film . Other information in- cludes the brand name and type and the expiry date for the film . To obtain maximum life from un- exposed film you should store it in a cool , dry place .
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