The Johnson BVRI set used at the ESO standard photometer of the 3.5m was choosen. Except for the I-filter they have the same characteristic as the filter system descibed by Bessell (PASP 88, 557: 1976)

• B-filter: 2mm GG385 + 1mm BG12 + 1mm BG18
• V-filter: 2mm GG495 + 1mm BG18
• R-filter: 2mm OG570 + 1mm KG3
• I-Filter: 3mm RG9

The H-alpha filter has the following characteristics:

• Central wavelength: 658.8nm
• Half power width: 4.0 nm
• radial velocity coverage: about -500 to +1500 km/s
• Transmission: >70%
• # cavities: 4
• Blocking: 0.01% from 380 to 1000nm