What part of the camera is the medium?

Clearly, one of the most important parts of a camera is the imaging sensor. As noted earlier, the sensor is where the focused light from the lens is directed and recorded. The information about light is recorded by millions of photosites, or pixels.

Explanation:

This format captures images that are slightly smaller than the large format film size (102x127mm) but are much bigger than those taken using full-frame sensors or 135 film.