What is a disadvantage of duplitized film?

The choice of the parallax effect as a disadvantage of duplitized film is accurate as this phenomenon can negatively impact image quality. Duplitized film consists of two emulsion layers on one film base, allowing for the capture of two images simultaneously. However, this setup can lead to alignment issues, resulting in multiple images or double imaging when viewed at an angle. This misalignment can be particularly detrimental in situations requiring precise imaging, such as in radiographic applications.

Other options, while they may have their own implications, do not directly align with the inherent disadvantages posed specifically by duplitized film. For instance, film speed refers to the sensitivity of film to light, which is generally a beneficial feature rather than a disadvantage. The presence of blue dye is relevant to certain film types but doesn't specifically detract from the operational efficiency of duplitized film. Lastly, contrast loss can occur in various film types due to multiple factors, but in the context of duplitized film, the parallax effect stands out as a unique and critical disadvantage that can impact the overall quality and utility of the images produced.