Astronomy Bandpass Filters are used to filter out and measure specific bands of light emitted by astronomical and celestial objects. Johnson/Bessel filters are well suited for use with photomultiplier tubes and Kron/Cousin filters are well suited for use with Silicon sensors because of the sensors’ responsivity. Both types of filters utilize identical UV (U), Blue (B), and Violet (V) filters. However, the Red (R) and Infrared (I) filters are optimized for use with either a photomultiplier tube or silicon CCD detector. Astronomy Bandpass Filters have precisely controlled thicknesses to minimize the common problem of refocusing when changing filters.