Variants: Lunasix, Lunasix 3, Lunasix 3s
Type: Ambient exposure meter
Display: Pointer needle with mechanical computer
Measurement angle: 30° reflected, 180° incident
Multiple measurements: no
Ambient sensitivity: -8 to +24LV (Lunasix 3 -4 to +24LV)
Flash sensitivity: N/A
ASA/ISO range: ISO 8 to 2,500
Incident light: Yes
Reflected light: Yes
Flash measurement: No
Aperture range: f 1 to 90
Time range: 1/4,000s to 8 hours
Battery: 2×mercury (later 2×silver oxide)
The 1961 Gossen Lunasix (in US Luna Pro) is a hand held exposure meter. Sold for many years the Lunasix was famed for its low light sensitivity, still impressive by today's standards. It was the company's first light meter not based on a selenium light receptor. The styling, layout, and distinctive "computer" dial set the standard for successive Gossen meters until the advent of electronic displays.
In 1966 the revised Gossen Lunasix 3 (in US Luna Pro S) was introduced, the main difference being a range of clip on accessories. A later revision changed from the original mercury batteries, these models being distinguished by a black case. Finally, the computer dial was replaced by the Lunasix F dial which incorporated exposure compensation, this version called Lunasix 3s.
The Lunasix 3 introduced the standard incident light dome and meter front end aperture for clip on accessories that featured on every Gossen professional meter until the completely restyled Variosix F of 1990.
The Lunasix was Gossen's flagship meter until the 1977 Profisix and remained available for some years afterwards.
The meter movement and operating mechanism are mechanical, however the CdS light cell requires battery power. Measurement is made by depressing the rocker switch in one direction for low light, and the other for daylight. When the rocker is released the needle remains clamped in place making transfer of the reading to the "computer" ring much easier.
A range of clip on accessories extended the measurement possibilities. These accessories would also fit any of the other Gossen professional meters until the completely redesigned Variosix F
- Measuring probe for view cameras and negative measurement (densitometry)
- Tele attachment for selective measurement 15° and 7.5°
- Micro attachment for microsocope measurement
- Lab attachment for enlarger measurement
- Repro attachment for reproduction (document copying) measurement