Gossen Profisix / Lunasix F
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
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
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.
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.
|Gossen Lunasix F|
image by Gitzo73 (Image rights)
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
image by Nesster (Image rights)
|Type||Null pointer hand held exposure meter|
|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|
|Dimensions||120 x 44 x 70mm|
|*Profisix flash measurement with optional attachment|