These are samples from Leitz 560mm f/6.8 Telyt-R lens and various Pentax digital SLR's.
Old but still works. Optical design: 2 elements, cemented together to make a single optical group with only 2 air/glass interfaces.
Leitz 560mm f/6.8 Telyt-RLeitz 560mm f/6.8 Telyt-RLeitz 560mm f/6.8 Telyt-RLeitz 560mm f/6.8 Telyt-RLeitz 560mm f/6.8 Telyt-RLeitz 560mm f/6.8 Telyt-RLeitz 560mm f/6.8 Telyt-RLeitz 560mm f/6.8 Telyt-R��czak (Tringa glareola)Leitz 560mm f/6.8 Telyt-RLeitz 560mm f/6.8 Telyt-RLeitz 560mm f/6.8 Telyt-RLeitz 560mm f/6.8 Telyt-R