The preslit devices of the Nasmyth-2 focus of the 6-m telescope:

• 1 - flat mirror of the field TV viewer,
• 2 - optics of the field TV viewer,
• 3 - TV viewer,
• 4 - hollow cathode lamp,
• 5 - continual spectrum lamps,
• 6 - balance filter,
• 7 - optics of the calibration channel,
• 8 - flat mirror of the calibration channel,
• 9 - circular polarization analyser,
• 10 - Fabry-Perot etalon,
• 11 - Jodine cell,
• 12 - beam splitter unit,
• 13 - dekkers turret of echelle spectrographs,
• 14 - mirror of dekkers viewer,
• 15 - Main Stellar Spectrograph (MSS) slit unit,
• 16 - optics of viewer of dekkers turret and of the MSS slit,
• 17 - TV viewer of dekkers turret and of the MSS slit,
• 18 - TV viewer filters turret.