TYPE: Spectra Professional IV-A-SP Advanced Digital Exposure Meter for measuring both incident, reflected and 1 degree spot measurement.
TECHNOLOGY: For highest accuracy and reliability it utilizes an advanced front end op amp, a custom sealed hybrid electronic circuitry, a multiple range linear circuit controlled by advanced mirco-computer and a custom liquid crystal display with aviation green backlit electro-luminescent lamps.
LIGHT SENSOR: Silicon photovoltaic cell with computer selected glass filters tailored to the spectral response of the film. Swivel head assembly turns 270 degrees.
MEASURING CAPABILITY: Direct readout of photographic exposures. Measures contrast ratios and average in f-stop., Features both illuminance and luminance modes: illuminance level in f/stop, footcandles (fc) and lux (lx), and luminance in f/stop and footlamberts.
MEASURING RANGE: One million to one (20 f/stop) -- widest sensitivity range available!
ILLUMINANCE/INCIDENT MODE: Digital f/stop: f/0.35 to f/128 in 1/10 stops
increments Analog bargraph f/stop: f/0.7 to f/45 in 1/3 stops increments Footcandles 0.1 to 70,000 and lux 1 to 100,000
LUMINANCE/REFLECTED MODE: (thru the lens of 1 degree Photospot)
Digital f/stop: f/0.35 to f/128 in 1/10 stops increments
Analog bargraph f/stop: f/0.7 to f/45 in 1/3 stops increments
Footlamberts: 0.1 to 70,000 (fl)
CONTRAST RATIO: Calculates ratio of two readings-- key plus fill to fill light alone, from 1:1 to 999:1. F/stop Difference: The difference in f/stop between a new reading and the last stored/memorized measurement is display in precise 1/10-stop increments up to plus or minus 12 f/stop.
AVERAGING: Average of two readings and/or continuous averaging in f/stop, footcandle and Spot metering modes are made possible.
FILM SPEED: ISO 3 TO ISO 8000 in 1/3-stop increments
FRAMES PER SECOND: 2 TO 360 (for motion picture cameras)
EXPOSURE TIME: 1/8000 sec to 30 minutes.
RESOLUTION: Digital 0.1-stop. Analog 0.2-stop.
ACCURACY: Digital 0.05 f/stop. Calibration is traceable to National Institute of Standard Technology (NIST) Washington, D.C.
ADDITIONAL FUNCTIONS: Memory Recall switch to recall stored reading in memory (M1), second reading in memory (M2) and/or the ratio average and f/stop difference of the two readings.
INSTANT RECALL OF ALL MEASUREMENT AND CALCULATIONS: By pressing the recall (RCL) switch, the first stored/memorized reading (M1), the second stored/memorized reading (M2), contrast ratio or brightness (f/stop) difference average footcandle/lux or average f/stop, can be recalled.
IMMEDIATE UPDATE OF ALL EXPOSURE CALCUATIONS: If the film speed (ISO), frames per second/Cine (FPS) or exposure time/Still (TIME) settings are changed, the f/stops are immediately recalculated and displayed in normal, f/stop difference, or average modes.
MEMORY ERASURE: You can erase the stored/memorized readings in memory (M1) and memory (M2) by pressing the store (STR) and recall (RCL) switch simultaneously.
CAMERA SHUTTER ANGLE: Complete list of shutter angles and equivalent compensation table conveniently provided in the instructional material.
BRIGHT GREEN DISPLAY: Electro-luminescent lamp for viewing displayed measurements at very low light levels.
POWER CONSUMPTION: Operation 5mA/reading. Data Retention 5μA.
POWER SOURCE: One 6 volt battery; No.’s A544, PX28l, PX28.
BATTERY LIFE: Approximately six months normal use.
DIMENSIONS: 5-1/2” X 2-1/2” X 2”
WEIGHT: Approximately 6 ounces.