Here we are comparing two Mirrorless cameras from Nikon and Canon. Both Z5 and R5 were launched within the same month in July 2020, so we are expecting this to be a fair comparison regarding age and available technology level.
The size of the imaging sensor is a crucial determinant of image quality. A large sensor will generally have larger individual pixels that offer better low-light sensitivity, provide wider dynamic range, and have richer color-depth than smaller pixels in a sensor of the same technological generation. Furthermore, a large sensor camera will give the photographer more possibilities to use shallow depth-of-field in order to isolate a subject from the background. On the downside, larger sensors tend to be associated with larger, more expensive camera bodies and lenses.
Both cameras under consideration feature a full frame sensor, but their sensors differ slightly in size. The sensor area in the Z5 is 1 percent smaller. They nevertheless have the same format factor of 1.0. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.