BS 5550-2.7.2:1982

Foreword
Cooperating organizations
Section one. General
1 Scope
2 References
3 Definitions
4 Instruction manual and marking
Section two. Design and construction
5 Design
6 Speed of projection
7 Projector lens assembly
8 Accessibility of optical and other parts for
    cleaning
9 Picture aperture
10 Framing and tilt
11 Picture-sound separation
12 Electrical and safety requirements
13 Light source
14 Lamphouse ventilation
15 Optional facilities
Section three. Picture performance
16 General
17 Preliminary setting up
18 Light output
19 Distribution of screen illumination
20 Colour bands in the image
21 Picture steadiness
22 Travel-ghost
23 Image resolution
24 Alignment and position of film plane
25 Flicker
Section four. Sound performance
26 General
27 Projectors with photographic sound systems
28 Projectors with magnetic sound systems
29 Amplifier
Section five. Mechanical tests with film
30 Test requirements
31 Test film
32 Loop tests
33 Fast winding without unthreading tests
34 Feed, reverse, still-picture, take-up and rewind
    tests
35 Loop reformer test
Appendices
A Requirements specific to projectors with discharge
    lamps
B Alternative picture unsteadiness test film
C Weighting network for measurement of amplifier noise
    with projector not running
D Measurement of photographic sound system noise
E Test of erasure efficiency
F Test of the total system signal-to-noise ratio
G Warning symbol
Tables
1 Signal-to-noise ratios for projectors with magnetic
    sound systems
2 Amplifier characteristics
3 Take-up and rewinding
4 Reverse take-up
5 Perforation strain
6 Perforation strain, reverse take-up
7 Change of direction while running test
Figures
1 Light output
2 Distribution of screen illumination
3 Warning symbol
4 Weighting curve A
5 Cut-outs for loop reformer test