a b

1. ab presents today

2. A closer look at the production process of a movie soundtrack. What elements are affecting recorded sound quality ?

3. Back to basics for only a moment... - Silver halide crystals were found to be light sensitive - Being light sensitive means that these grains are able to absorb photons or quanta of light energy. - Absorption is not evident, but function of different parameters (photon energy, angle of incidence…) - Photon energy is defined by it’s wavelength, and to be high enough, wavelength must be shorter than 495 nm. - Having absorbed the threshold number of quanta makes a grain developable. - Once the threshold is reached, any further absorbed quanta are wasted and have no further contribution to image forming. - For practical reasons, grains are dispersed in a light sensitive emulsion and coated on a transparent base.

4. Some fundamentals to remember... • even without exposure, eventually all grains will be reduced to silver.(when brought in contact with the developer) • the rate of this reduction is much higher for those grains, having absorbed the threshold number of energy quanta. • the latent image is formed by the above mentioned grains.. • in theory, grain size defines the maximum resolving power. • absorption and collision of photons and silver halide grains is a pure statistical phenomenon. • because of these collisions, spreading of the image will occur. • and as we know, control of image spread can be prohibitive for the quality of analogue and digital sound tracks.

5. Let’s have a look at this phenomenon. emulsion layer base (polyester)

6. How to reduce image spread. reduce thickness of the emulsion layer 1 2 increase base density because of the low printing speed in “those” days, and hence the availability of enough light, increasing base density was an acceptable solution. this is why “grey base” was introduced years ago.

7. How does it work. Less spreading of the image and hence and increased sharpness ! - An increased base density reduces intensity of the reflected light. - This reduction decreases probability of absorption. - However this probability will never be zero. - So if there’s a collision, image spread can be relatively high also. An elegant solution for this problem is, - To use a normal transparent polyester base, and - To add an extra (anti halation) high density layer between the emulsion package and the base, of which - dye’s are loosing (in a controlled way) density during processing. The result will be...

8. A few complications... • to increase resolving power (sharpness) of the material, grain size can be reduced. • to increase the probability of collision between photons and grains (and therefore increase speed), grain size must be increased. Therefore the higher the sharpness of a material (with the same amount of silver), the lower the sensitivity.

9. And even more... • increasing sharpness will result in a reduced image spread. • therefore, to obtain the same level of image spread, a sharper material needs a higher aim density. Conclusion Whatever a film manufacturer will change in photographic characteristics, it will always have an impact upon practical settings as aim densities and or exposure values.

10. And what about contact printing ? sound negative colour positive

11. Elements affecting sound quality. Sound negative characteristics Sound camera exposure Colour positive characteristics Printing process Black & White processing Colour processing Reproduction (projector characteristics) Conclusion The final quality (frequency response) depends upon every detail in the production process.

12. Let’s have a look at the total frequency response.

13. And what about the sound level ? colour print light source and optics detector and optics Sin (wt) 1 - Sin (wt) S(t)= + 10Dmin 10Dmax Dmax Dmin

14. One slide with some mathematics Sin (wt) 1 - Sin (wt) S(t) = + 10Dmin 10Dmax Sin (wt) Sin (wt) 1 S(t) = - + 10Dmin 10Dmax 10Dmax Example: with Dmin = 0.20 and Dmax = 1.2 we obtain S(t) = 0.57. Sin(wt) + 0.06 with 1/10Dmax neglected, 1 1 S(t) = ( - ) Sin (wt) 10Dmin 10Dmax

15. The previous formula visualized Dmin = 0.1 Dmin = 0.21 Conclusions Cyan dye tracks (on a red reader) produce 33% more output. At Dmax = 1.5 the output level reaches more than 95% !!

16. And what about digital tracks ..? Reference to measurements, carried out on the Dolby Digital signal. Both sources of information, shape of the dots as well as density scans are used in an attempt to reveal the digital printing process.

17. Influence of B&W chemistry upon density reconstruction in a sound negative PROCESSING CONDITIONS A Camera setting Camera setting 11 Camera setting 15 Camera setting 19 B

18. Densitometrical dot shape is very important And therefore, a standardized B&W chemistry is an issue.

20. Let’s make a simulation... Starting with the characteristic curve Density Exposure energy

26. dD If we define a detection range as being the difference in minimum and maximum signal level..

27. We can calculate the range dD as a function of exposure level. Or even the maximum density value of the dots in the colour print. And therefore if the glitches where the only players in the game, it would be easy to make the optimum parameter choices !!

28. But, there’s also image spread !! 18m !!

29. And image spread can destroy information At a certain moment Dmin starts to increase

30. Let’s therefore have a look at the relationship between detection margin and image spread... 5 to 6 m Dred= 1.3

31. General Conclusions. - a standardization of aim densities would be very welcome - with high magenta tracks being a reality and cyan dye technology coming up, also filter characteristics should be “common knowledge”. - there’s a need for a stable and “easy to use” black & white processing. Our proposal A- Is to set up a specialized committee, with the objective to determine, for all kinds of motion picture sound recording technologies, a standardized practical set of aim densities and filter characteristics. B- To act quickly and to communicate the findings of this committee asap to all participants.

32. Finally, what’s new from AGFA ? We improved our ST9 significantly ! - Because they have been good all the time, there was no need to improve the photographic characteristics. - So we concentrated on physical performances... - And we improved the mechanical resistance dramatically! - We made our sound negative permanent anti static ! That’s it for now ...