Why Do Opening and Closing Credits in Older Movies Shake on TV?

Ever wondered why the opening and closing credits on some older movies seem to create a slight shaking effect? This phenomenon is often attributed to a term known as film ride. The image from film playing on TV appears to bounce around slightly and becomes more noticeable when there is text on the screen. To understand this, we need to delve into the history and technology behind movie projection and how such effects often arise from the conversion process.

From Film Speed to TV Playback

Movies are primarily shot at a frame rate of 24 frames per second (fps) and projected similarly. However, when these films are converted for TV or streaming, they are often upgraded to a higher frame rate, typically 30 fps. This conversion process can introduce a slight movement in the image, which is particularly noticeable during quieter scenes or when text is displayed on the screen.

The Impact of Negative and Print Quality

While most modern films do not exhibit this shaking, it can occur if the sprocket holes on the negative or print used in projection are worn or enlarged. Sprocket holes, also known as edge perforations, play a crucial role in holding the film in place during projection by engaging with registration pins. These pins ensure that each frame of the film is precisely positioned, which is why any variation in their position results in picture wobble.

No More Wobble with Optical Printer?

Before the 1990s, films, including their opening and closing credits, were all created on film. To superimpose these credits over images, an optical printer was used. This device re-exposed different elements, such as the main image, titles, and visual effects, onto a new single roll of film, creating a composite image. During this multi-pass process, there was nearly inescapable variation in registration, leading to the apparent movement of the title over the image, under the image, or both.

Understanding the Mechanical Precision of Film Projection

When film travels through a camera or projector, it moves intermittently one frame at a time, 24 times per second. This mechanical precision is crucial; any positional variation from one frame to another will be visible as picture wobble. Registration pins are used to hold the frame firmly in place by engaging with the sprocket holes, or edge perforations. If the equipment lacks registration pins, it may only use a pull-down claw, which functions similarly to a sewing machine needle, but in an elliptical path rather than a linear one.

Age and Environmental Factors

As film ages, or when it is exposed to changes in humidity, there can be a slight variance in registration, causing the image to subtly bounce or weave. This effect is present in all projected film, but it is typically not noticed due to the overall smoothness and structural integrity of the film. However, when the text over an image makes it more apparent, this phenomenon becomes quite noticeable.

Conclusion

The shaking effect seen in the opening and closing credits of older movies is a result of the conversion from 24 fps film to higher frame rates on TV and streaming platforms. It can also be attributed to the wear and tear of the film itself, particularly in the sprocket holes. While this may not be a significant concern for modern films, it is a fascinating aspect of the history and technology of cinema that sheds light on the challenges of preserving and adapting film for different viewing mediums.

Keywords: film ride, optical printer, registration pins, sprocket holes, superimposed titles