In astrophotography, pixel size refers to the physical size of an individual pixel on a camera’s image sensor. It is usually measured in micrometers (µm) and can have a significant impact on the image quality and resolution of astrophotographs.

A smaller pixel size generally allows for higher resolution images with more detail, but can also result in a lower signal-to-noise ratio due to smaller photon collecting areas. On the other hand, larger pixel sizes typically have lower resolution but higher sensitivity to light.

When choosing a camera for astrophotography, the pixel size is an important factor to consider depending on the desired field of view, focal length of the telescope, and other factors that may impact the overall image quality.