Page "Photometer" Paragraph 15

In airborne and space-based remote sensing such photon counters are used at the upper reaches of the electromagnetic spectrum such as the X-ray to far ultraviolet.

This is usually due to the lower radiant intensity of the objects being measured as well as the difficulty of measuring light at higher energies using its particle-like nature as compared to the wavelike nature of light at lower frequencies.

Conversely, radiometers are typically used for remote sensing from the visible, infrared though radio frequency range.