تويت
التصوير الفوتوغرافي الحديث
صنع صور متحركة للتلفزيون
تحقيق تأثيرات خاصة
حركة بطيئة وسريعة
إيقاف الحركة
المعدل الزمني للتصوير
ACHIEVING SPECIAL EFFECTS
In Assignment 19 , we have discussed some of the more special effects which the advanced amateur or the student can use to improve his films . They can , of course , also be used in professional motion picture photography , but ordinarily they should be used with discretion . The ordinary motion picture has a strong story line , a good plot and logical action . Special effects should be used only if they contribute something useful which cannot be achieved with more ordinary techniques . Used to excess , special effects are likely to interfere with the development of the story .
In television the situation is quite different and special effects are widely used . A TV commercial , for example , is quite short , generally running to a minute or less . The advertiser's message must be gotten over with force and emphasis during this short period - there simply isn't time enough to develop a story by conventional means . Furthermore , the viewer is primarily interested in the program itself , and to him the commercial is a necessary evil at best , a distraction or a serious annoyance which may give him the opportunity of leaving the set to take care of some urgent personal business or to shut off the set completely if the program isn't quite good enough to overcome the irritation of the commercial . Under these circumstances , the commercial must attract the viewer's attention instantly and keep him glued to the set so he doesn't switch to another channel . Special effects can be used to give the commercial the dramatic impact it needs to retain the audience .
Special effects are also used in the program material itself . In movies made for the theater , cost seems to be no object . If the story calls for a scene in any part of the world , a crew may be sent there to shoot it even if it is on the screen for only a few seconds . Such extravagance is not possible for the ordinary television show with its much more limited budget . However , it is surprising how much can be achieved at very little cost through the use of special effects .
Some special effects require quite elaborate equipment and a good deal of trick photography but much can be accomplished with ordinary equipment . Some of the more simple effects have already been covered in a general way in Assignment 19 , but we will discuss them here from the special point of view of their use in television .
SLOW MOTION AND FAST MOTION
As you know by now , if you film a scene at one speed and project it at a higher speed , motion is speeded up . If you project it at a lower speed , motion is slowed down . It is usually more convenient to keep the projection speed constant and vary the taking speed of the camera so that you would get speeded up motion . by shooting at a lower than normal speed . But there are occasions when you may want to reverse this procedure .
Slow motion is ordinarily used to permit a more detailed study of the object or subject in motion , but it can also be used for dramatic effect or to achieve a certain mood . One very effective commercial shows a girl just past her teens running directly toward the camera in long graceful strides . The effect was one of extraordinary grace and the reaction of youth to the beauty of the outdoors .
A somewhat different approach to slow motion is frequently used in the photography of sports . Where the pace is fast and anything can happen , the photographer must keep the camera focused on the main action so as not to miss anything important . Sometimes an exciting bit of action is so fast that it is through before the viewer can grasp what the camera captured . Action in such cases is usually so unexpected that the photographer doesn't have time to switch to slow motion and he , therefore , continues shooting at normal speed . However , slow motion can be introduced when a print is made through the use of special optical printing equipment .
For example , the ordinary procedure when making a print is to have the negative and the positive run through the printer at the same speed so that for every frame of the negative there is a corresponding frame on the positive . However , it is possible to make a print in such a way that for every frame of the negative there are any desired number of frames on the positive . For example , if there are four frames on the positive for every frame on the negative , the action takes four times as long when it is projected , and we have slowed up action by that degree . This type of slow motion is very jerky because the action was so fast that there was quite a bit of motion from one frame to the next on the original and this gap cannot be filled in by any process of printing . Nevertheless , it does achieve its prime purpose , to slow up the action so that it can be studied .
Slow motion is often used photograph small objects such as toys and models . These usually seem to be moving too rapidly when photographed at normal speed so that slowing down the motion slightly often produces a more natural effect . It requires a certain amount of skill and experience to judge just how much the motion should be slowed .
STOPPING MOTION
It is sometimes necessary to stop motion completely for a specified length of time . In an educational film , for example , the narration may take much longer than the action and this is one way of stopping the action so that the narrator can explain what is going on . This technique is also used to good effect to introduce the characters at the beginning of a story . As an example , a short scene is selected in which a leading character gets out of a car and walks toward the camera . When he gets close enough , the action is stopped and while he is motionless on the screen , his name and other information is superimposed for a brief period . This method of introducing the principal characters of a TV play is much more . effective than the more common one of simply listing them the introduction .
Stopping or freezing motion in this way is a very simple technique . Decide how long the action is to be stopped and multiply this time in seconds by the number of frames per second for the film and speed you are using ( see Table II , Assignment 19 for this information ) , and have the processing laboratory run off a duplicate strip of this frame to the required length . Then splice it into the action footage at the required point . If any printed material is to be superimposed on the stopped frame , shoot that separately and give that to the laboratory with the action film so they can take care of the double exposure effect . The procedure is quite routine and offers no difficulties to the laboratory .
TIME - LAPSE PHOTOGRAPHY
Time - lapse photography is really slow motion carried to an extreme . The exposure is made one frame at a time with a considerable pause or lapse of time between exposures . It is usually used to show action which normally proceeds so slowly that ordinary photography cannot be used . For example , the blossoming of a flower , the germination of a seed , or the hatching of an egg can all be speeded up so that they seem to go through the entire cycle from beginning to end in a matter of seconds .
In making a time - lapse sequence , you will first determine how long you want it to show on the screen . Then translate this interval of time into frames of motion picture film . This gives you the number of exposures you want . The next step is to determine the actual time it takes for the process you are photographing to complete its cycle . Divide this time by the number of frames you want , and this gives you the interval of time between exposures .
For example , let us assume you want to show some life process in a short scene which is to last 10 seconds on the screen . You will be shooting at sound speed , which is 24 frames per second so that you will need 240 frames . Let us assume that this life process actually takes four days . There are 24 hours or 1,440 minutes in a day , so that the total lapsed time will be 9,760 minutes . During this interval of time , you want to expose 240 frames , so divide 9,760 by 240 and the approximately 40. This bit arithmetic tells us that we must expose one frame every 40 minutes over the four days to get the action we want . Actually we would probably set up the camera several hours before we want the action to start and let it run for several hours after the action is completed to give us a few extra frames at each end for handling and splicing .
The actual photography should be done indoors so that it will be independent of the weather and of outdoor lighting . Each frame must receive exactly the same exposure as all the others , and this can be done only if excluded aside from the lighting established expressly for the time - lapse sequence . Because the exposure is made over a period of four days , it is not practical to keep the lights on all the time , so that a special timing device and relay is required . The timer should be set so that the following sequence of events occurs every 40 minutes . The lights go on first , then the single exposure button of the camera is pressed and finally the lights go off again . At the end of four days , plus a few hours as a safety factor , the job is done and the film can be processed .
The timing device and relay equipment is rather special in its nature , but it can be rented if the amount of work that is to be done does not warrant its purchase .
If the time - lapse photography is of a simpler nature and takes place over a much shorter period of time , you may dispense with the automatic timing and relay equipment . On the other hand , if you want to photograph a long time process which requires daylight , such as an apple growing on a tree , the set - up becomes quite elaborate and requires a good deal of practical experience .
صنع صور متحركة للتلفزيون
تحقيق تأثيرات خاصة
حركة بطيئة وسريعة
إيقاف الحركة
المعدل الزمني للتصوير
ACHIEVING SPECIAL EFFECTS
In Assignment 19 , we have discussed some of the more special effects which the advanced amateur or the student can use to improve his films . They can , of course , also be used in professional motion picture photography , but ordinarily they should be used with discretion . The ordinary motion picture has a strong story line , a good plot and logical action . Special effects should be used only if they contribute something useful which cannot be achieved with more ordinary techniques . Used to excess , special effects are likely to interfere with the development of the story .
In television the situation is quite different and special effects are widely used . A TV commercial , for example , is quite short , generally running to a minute or less . The advertiser's message must be gotten over with force and emphasis during this short period - there simply isn't time enough to develop a story by conventional means . Furthermore , the viewer is primarily interested in the program itself , and to him the commercial is a necessary evil at best , a distraction or a serious annoyance which may give him the opportunity of leaving the set to take care of some urgent personal business or to shut off the set completely if the program isn't quite good enough to overcome the irritation of the commercial . Under these circumstances , the commercial must attract the viewer's attention instantly and keep him glued to the set so he doesn't switch to another channel . Special effects can be used to give the commercial the dramatic impact it needs to retain the audience .
Special effects are also used in the program material itself . In movies made for the theater , cost seems to be no object . If the story calls for a scene in any part of the world , a crew may be sent there to shoot it even if it is on the screen for only a few seconds . Such extravagance is not possible for the ordinary television show with its much more limited budget . However , it is surprising how much can be achieved at very little cost through the use of special effects .
Some special effects require quite elaborate equipment and a good deal of trick photography but much can be accomplished with ordinary equipment . Some of the more simple effects have already been covered in a general way in Assignment 19 , but we will discuss them here from the special point of view of their use in television .
SLOW MOTION AND FAST MOTION
As you know by now , if you film a scene at one speed and project it at a higher speed , motion is speeded up . If you project it at a lower speed , motion is slowed down . It is usually more convenient to keep the projection speed constant and vary the taking speed of the camera so that you would get speeded up motion . by shooting at a lower than normal speed . But there are occasions when you may want to reverse this procedure .
Slow motion is ordinarily used to permit a more detailed study of the object or subject in motion , but it can also be used for dramatic effect or to achieve a certain mood . One very effective commercial shows a girl just past her teens running directly toward the camera in long graceful strides . The effect was one of extraordinary grace and the reaction of youth to the beauty of the outdoors .
A somewhat different approach to slow motion is frequently used in the photography of sports . Where the pace is fast and anything can happen , the photographer must keep the camera focused on the main action so as not to miss anything important . Sometimes an exciting bit of action is so fast that it is through before the viewer can grasp what the camera captured . Action in such cases is usually so unexpected that the photographer doesn't have time to switch to slow motion and he , therefore , continues shooting at normal speed . However , slow motion can be introduced when a print is made through the use of special optical printing equipment .
For example , the ordinary procedure when making a print is to have the negative and the positive run through the printer at the same speed so that for every frame of the negative there is a corresponding frame on the positive . However , it is possible to make a print in such a way that for every frame of the negative there are any desired number of frames on the positive . For example , if there are four frames on the positive for every frame on the negative , the action takes four times as long when it is projected , and we have slowed up action by that degree . This type of slow motion is very jerky because the action was so fast that there was quite a bit of motion from one frame to the next on the original and this gap cannot be filled in by any process of printing . Nevertheless , it does achieve its prime purpose , to slow up the action so that it can be studied .
Slow motion is often used photograph small objects such as toys and models . These usually seem to be moving too rapidly when photographed at normal speed so that slowing down the motion slightly often produces a more natural effect . It requires a certain amount of skill and experience to judge just how much the motion should be slowed .
STOPPING MOTION
It is sometimes necessary to stop motion completely for a specified length of time . In an educational film , for example , the narration may take much longer than the action and this is one way of stopping the action so that the narrator can explain what is going on . This technique is also used to good effect to introduce the characters at the beginning of a story . As an example , a short scene is selected in which a leading character gets out of a car and walks toward the camera . When he gets close enough , the action is stopped and while he is motionless on the screen , his name and other information is superimposed for a brief period . This method of introducing the principal characters of a TV play is much more . effective than the more common one of simply listing them the introduction .
Stopping or freezing motion in this way is a very simple technique . Decide how long the action is to be stopped and multiply this time in seconds by the number of frames per second for the film and speed you are using ( see Table II , Assignment 19 for this information ) , and have the processing laboratory run off a duplicate strip of this frame to the required length . Then splice it into the action footage at the required point . If any printed material is to be superimposed on the stopped frame , shoot that separately and give that to the laboratory with the action film so they can take care of the double exposure effect . The procedure is quite routine and offers no difficulties to the laboratory .
TIME - LAPSE PHOTOGRAPHY
Time - lapse photography is really slow motion carried to an extreme . The exposure is made one frame at a time with a considerable pause or lapse of time between exposures . It is usually used to show action which normally proceeds so slowly that ordinary photography cannot be used . For example , the blossoming of a flower , the germination of a seed , or the hatching of an egg can all be speeded up so that they seem to go through the entire cycle from beginning to end in a matter of seconds .
In making a time - lapse sequence , you will first determine how long you want it to show on the screen . Then translate this interval of time into frames of motion picture film . This gives you the number of exposures you want . The next step is to determine the actual time it takes for the process you are photographing to complete its cycle . Divide this time by the number of frames you want , and this gives you the interval of time between exposures .
For example , let us assume you want to show some life process in a short scene which is to last 10 seconds on the screen . You will be shooting at sound speed , which is 24 frames per second so that you will need 240 frames . Let us assume that this life process actually takes four days . There are 24 hours or 1,440 minutes in a day , so that the total lapsed time will be 9,760 minutes . During this interval of time , you want to expose 240 frames , so divide 9,760 by 240 and the approximately 40. This bit arithmetic tells us that we must expose one frame every 40 minutes over the four days to get the action we want . Actually we would probably set up the camera several hours before we want the action to start and let it run for several hours after the action is completed to give us a few extra frames at each end for handling and splicing .
The actual photography should be done indoors so that it will be independent of the weather and of outdoor lighting . Each frame must receive exactly the same exposure as all the others , and this can be done only if excluded aside from the lighting established expressly for the time - lapse sequence . Because the exposure is made over a period of four days , it is not practical to keep the lights on all the time , so that a special timing device and relay is required . The timer should be set so that the following sequence of events occurs every 40 minutes . The lights go on first , then the single exposure button of the camera is pressed and finally the lights go off again . At the end of four days , plus a few hours as a safety factor , the job is done and the film can be processed .
The timing device and relay equipment is rather special in its nature , but it can be rented if the amount of work that is to be done does not warrant its purchase .
If the time - lapse photography is of a simpler nature and takes place over a much shorter period of time , you may dispense with the automatic timing and relay equipment . On the other hand , if you want to photograph a long time process which requires daylight , such as an apple growing on a tree , the set - up becomes quite elaborate and requires a good deal of practical experience .
تعليق