A survey of magnetic recording for the motion picture film and its application to military film production

104 Pages·04.38 MB·English

by  Gray, Norman

A SURVEY OP MAGNETIC RECORDING FOR THE MOTION PICTURE
FILM AND ITS APPLICATION TO MILITARY FILM PRODUCTION
A Thesis
Presented to
the Faculty of the Department of Cinema
The University of Southern California
In Partial Fulfillm ent
of the Requirements for the Degree
Master of Arts
by
Norman Gray
Major, United States Army Signal Corps
June 1950
UMI Number: EP42686
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This thesis, written by
..........................
under the guidance of h..%3.. Faculty CommitteeK
and approved by all its members, has been
presented to and accepted by the Council on
Graduate Study and Research in partial fulfill­
ment of the requirements for the degree of
.................................
Date .Jyne...!9J2.Q.
Faculty Committee
Chairman
TABLE OK CONTENTS
CHAPTER PAGE
I. THE PROBLEM AND DEFINITIONS OF TERMS USED . . *1
The problem . . . . . . . . . . . 1
Statement of the problem .................... 1
Importance of the study . . .............................. 2
D efinitions of terms u s e d ....................................... 3
Magnetic recording . 3
Laminated film ............................. 3
M ilitary ............................................................................... 3
Organization of remainder of the thesis . . 3
Principles of o p e r a tio n . 3
Noise and d is to r tio n ................................................. l\.
Magnetic equipment • • • • ................................... Ij.
Advantages and disadvantages of magnetic
r e c o r d in g ...................................................................... 1|
Conclusions and recom m endations.................... I4.
History and present status of magnetic
r e c o r d in g ................................................................ £
History ................................................................................ 5
Present status ................................................................. 5
Sources of data and treatment of findings • 6
Sources of d a t a ............................................................ 6
Method of procedure .............................. 7
i i
CHAPTER PAGE
II. PRINCIPLES OP OPERATION ................................................... 8
Principles of magnetic recording ......................... 8
B ia s ................................................. lif
Lay-out of com p on en ts.................................................. 17
III. NOISE AM) DISTORTION............................................................. 22
Inherent noise lim itations ......................................... 22
Bias c u r r e n t.......................................................................... 23
F l u t t e r ................................................................................... 25
Overload characteristics . . . • • . . • • • 25
Frequency characteristics ......................................... 26
IV. MAGNETIC EQUIPMENT.................................................................. 31
E r a s e ....................................... 31
Recorder ............................. 32
F ilm .............................................................................................. 33
Film id e n t if ic a t io n ..................................................... 36
E d it i n g .................................................................................... I4.O
Laminated f i l m ............................................................... . I4.I
Processing of magnetic f i l m ................................... l\2
Spurious p r i n t i n g ............................................................ I4.6
R e e l s ......................................................................................... I4.7
P ro je ctio n ...............................................................................
V. ADVANTAGES AND DISADVANTAGES OF MAGNETIC
RECORDING ........................................................................... 50
Economy ....................................... 50
i i i
CHAPTER PA1E
Q u a lity .................................................................................... 5k
Equipment . ...................................................................... 57
F ilm .............................................................................................. 59
P ro cessin g ............................................................................... 62
P ro jectio n ........................ 63
VI* CONCLUSIONS AND RECOMMENDATIONS .............................. 65.
C o n c lu sio n s.......................................................................... 65
Recom m endations................................................................. 72
BIBLIOGRAPHY.............................................................................................. 7^
APPENDIX A* Proposed Standards 35-MM Film with
Magnetic Coating.................................................. 81
APPENDIX B* Proposed Standards 17s-MM Film with
Magnetic Coating • • • ............................. 81^
APPENDIX C* L etter from W riter to The Signal Corps
Photographic Center• • • • • • • • « 87
APPENDIX D* Letter from The Signal Corps Photo­
graphic Center to the W riter . • • • 90
LIST OF FIGURES
FIGURE PAGE
1« Method of Inducing Perpendicular Magnetiza­
tion in the Magnetic C a r r ie r .................................. 10
2* Method of Inducing Longitudinal Magnetization
in the Magnetic C a r rie r .................................................. 11
3* Staggering of the Pole Pieces Gives Longitudi­
nal Magnetization at Low Frequencies and
Perpendicular Magnetization at High
F requencies............................................................................... 13
if.* Relationship Between Remanent Induction and
Magnetizing Force ................................................................. 15
5* Process of Magnetic Recording U tilizin g a
Direct-Current Bias ........................ l6
6* Recording C haracteristics of Magnetic Film
Using an Alternating-Current B i a s ........................ 18
7* Film Path of the Magnetic R e c o r d e r ......................... 20
8* E ffect of Bias Current on Output and D istortion
for a Given Type Magnetic F i l m .............................. 2i\.
9* Magnetic-System Frequency Characteristic Which
Indicates the 6-DB-Per-0ctave Rise • • . • • 27
10* Magnetic-Recording Pre and Post-Equalization
Curves Giving a P ractically Uniformly Flat
Curve When Added Together ....................................... „28
FIGURE PAGE
11* Magnetic Film of the Minnesota Mining and
Manufacturing Company ................................................. 35
12* Film Splice on Magnetic Film Made by Cello-
Vision Magnetic Splicer .................................................. 39
13* Magnetic M aterial Laminated on One Side of
Film Base (E xaggerated)........................ 43
1 if* Magnetic M aterial Laminated on One Side of Film
Base with Dummy on Opposite Side 44-
15* Magnetic Coating of a Photographic Film
U tilizin g a Portion of the Film Base for
the Magnetic M a teria l...................................................... 45
CHAPTER I
THE PROBLEM AND DEFINITIONS OF TERMS USED
The United States Armed Forces are constantly str iv ­
ing to increase their efficien cy and effectiveness through
the adoption of new methods and procedures whose usefullness
are proven through continuous experimentation and research*
The u tiliza tio n of magnetic recording for the m ilitary film
presents the Armed Forces with a new method and procedure
which can increase the efficien cy and effectiveness of
m ilitary film production*
I . THE PROBLEM
Statement of the problem* It is the purpose of this
study (1) to review the progress which has been made in the
recording of sound for motion pictures through the use of
magnetic film ; (2) to discuss equipments and procedures' which
must be developed in order that the m ilitary forces can adopt
magnetic recording; (3) to present the problems involved in
converting from photographic recording to magnetic recording;
and (if) to present logica l recommendations for the adoption
of magnetic recording by the m ilitary forces* Recommenda­
tions and conclusions contained herein are based on solutions
to sound recording problems in the commercial fie ld and ex#
perience of the writer in the m ilitary training field *
2
Importance of the study* The expanded peace time
Army is spending lite r a lly m illions of dollars annually in
order to train and keep m ilitary personnel informed, through
the use of the motion picture. During war, these expenditures
are increased many many times.
In peace time, the Army frequently sends photographic
teams into the fie ld to obtain necessary sequences for film s
in production. During war, combat photographers shoot
thousands of feet of film of actual combat operations, foot­
age which is u tilized in the training of personnel for fu­
ture operations as w ell as for information and h istorical
purposes. The problems of recording good quality sound dur­
ing combat operations are extremely d iffic u lt, and to a
great extent they are also present in peace time on m ilitary
maneuvers and in the fie ld .
By conducting a survey of magnetic recording and d is­
cussing its advantages as w ell as disadvantages for m ilitary
film production, recommendations can be made which may
enable the m ilitary to obtain better quality sound with
increased efficien cy and economy. It is anticipated that
this study w ill be made available to appropriate m ilitary
personnel for consideration in the formulation of future
plans and p o licies pertaining to sound recording for the
m ilitary film .