Gossen Profisix / Lunasix F

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Gossen Profisix

Maker: Gossen

Dates: 1977-1983

Variants: Profisix, Lunasix F, Lunalite

Type: Null pointer ambient and flash meter


Display: Pointer needle with mechanical computer

Sensor: SBC (silicon blue diode)

Measurement angle: 30° reflected, 180° incident

Multiple measurements: Flash

Ambient sensitivity: -5 to +24LV

Flash sensitivity:

ASA/ISO range: ISO 0.8 to 100,000

Incident light: Yes

Reflected light: Yes

Flash measurement: Yes

Aperture range: f 0.7 to 128

Time range: 1/4,000s to 8 hours

Battery: 9V

Weight: 250g


The 1977 Gossen Profisix (in US Luna-Pro sbc) is a professional "system" exposure meter that can be fitted with a range of electrically connected accessories offering additional measurement facilities, including flash, enlarger metering, and colour temperature. The "Profi-System" line continued and ended with the Mastersix.

The 1981 Gossen Lunasix F (in US Luna-Pro F) was developed from the Profisix. In spite of its name, it is not related to the Lunasix at all, but does share the same range of clip on accessories. Flash metering was incorporated, however sensitivity was reduced compared to the Profisix as was the range of accessories (Profisix accessories will not fit the Lunasix F). The Lunasix F was Gossen's last professional meter with a mechanical moving needle display and the last without a microprocessor.

A lower cost version, the Gossen Lunalite (in US Luna-Lux), substituted the mechanical meter with an LED array. It has further reduced sensitivity and does not provide flash metering.

In spite of mechanical display and "computer" dial, these meters are electronic as circuitry to store the light reading is necessary for flash measurement. The electronics shut off after 30 seconds.

The Profisix was Gossen's flagship professional exposure meter and likewise its replacement Mastersix. The Lunasix F was positioned alongside the Lunasix and in turn was replaced by the Multisix. Both meters were high cost items.


Measurement

The Profisix is a zero or null pointer measurement meter. In use, the measurement button is pressed briefly to take a measurement and then the coupled computer dial rotated in the indicated direction until the needle aligns with zero ("zeroed" or "nulled"). Exposure settings are then read from the computer dial, the lower window of which displays the measured EV ("Exposure Value"). The main meter scale is also marked for over or under exposure.

Zero / null exposure pointers are common in cameras but very unusual in separate meters. There are several advantages:

  • Once zeroed, exposure settings can be immediately read off the computer dial. Conventional moving pointer meters require the measured value to be manually transferred to the computer dial before reading exposure settings.
  • The centre zero position eliminates scale errors of the mechanical meter movement making measurements more accurate & consistent
  • By holding the reading button and pointing from high to low light areas the contrast range can be very quickly assessed

The computer dial incorporates standard exposure compensation, exposure factor compensation for filters or close up work, as well as I - IX steps for zone exposure. The dial has three separate rings:

  • The outer ring is coupled to the meter mechanism and used to zero the meter needle when making measurements. It has shutter speeds marked on it which align with the inner ring aperture scale giving exposure settings for the measured illuminance
  • The innermost ring is used to set film sensitivity and has the aperture scale marked on it
  • In between is the exposure compensation ring, marked +/-EV on its upper half and EF ("Exposure Factor") on its lower half. It is used to apply ongoing exposure compensation such as when using a filter


Specifications

Profisix Lunasix F Lunalite
Type Null pointer hand held exposure meter
Introduction 1977 1981
Sensor SBC (Silicon Blue Cell)
Measurement Ambient & Flash* Ambient
Sensitivity -5 to +24 LV -1 to +17 LV +1 to +17 LV
Display -3 to +3 EV Pointer 3 LED
Film Speed ISO 0.8 to 100,000
Aperture f 0.7 to f 128
Time 1/4,000s to 8 hours
Power 9v Battery
Dimensions 120 x 44 x 70mm
Weight 250g 195g 170g
*Profisix flash measurement with optional attachment

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