Spectra Professional IV-A-SP Spot Metering System
Measures Incident/ ambient and 1º Spot reading


Model 18007 Spectra® Professional® IV-A-SP
Advanced Digital Exposure Meter

   The Spectra Professional IV-A-SP is a unique optical exposure meter system. Simply attaching the Spectra Professional IV-A Advanced Digital Exposure Meter (ADEM) to its Spectra┬« One Degree Photospot converts your Spectra Professional IV-A into a high-sensitivity, one-degree Spotmeter for narrow-angle reflected-light measurements.
Spectra Professional IV-A-SP Exposure Meter PhotoSpot System model # 18007-ASP is an Advanced Digital Exposure Meter for motion picture video and digital photography applications.

   Without the Photospot attached, the Spectra Professional IV-A-SP measures incident light intensity directly in f/stops, footcandles and lux. And in spot-metering mode with the Photospot attached (through the lens viewfinder, bright erect 1░ PhotoSpot ) f/stops and footlamberts can be measured. Plus, you can instantly calculate f/stop difference, contrast ratio, and the average of your particular lighting situation. This last feature is a Spectra exclusive.

   The Spectra Professional IV-A-SP has a digital f/stop measuring range that extends from f/0.35 to f/128 in 1/10-stop increments and an Analog Bargraph range from f/0.7 to f/45 in 1/3-stop increments, in both incident and reflected (one-degree spot) modes. Readings are displayed simultaneously on a backlit liquid crystal display, along with film-speed, frames per second for cine use, and exposure time for digital photography.

   The Spectra Professional IV-A-SP is designed to measure highly accurate light intensity and covers illuminance levels from 0.1 to 70,000 footcandles and 1 to 100,000 lux. And in the reflected spot metering mode, measurement levels are from 0.1 to 70,000 footlamberts. -- that is a sensitivity dynamic range of almost one million to one!

Spectra Professional IV-A-SP offers a number of important advantages:
Widest Sensitivity Range Ever!
Measures f/stop from f/0.35 to f/128, photographic illuminance from near total darkness- 0.1 footcandles to full 70,000 fc and 1 to 100,000 lux. And in spot metering mode, from 0.1 to 70,000 footlamberts.
Contrast Ratio Measurements (Ratio mode)
The ratio of two readings from l:l to 999:1 can be instantly calculated and displayed thereby simplifying the set up of any lighting situation. And in f/stop mode the difference in f/stop between a new reading and the last memorized measurement is displayed in precise 1/10 –stop increments.
The average of two readings and/or continuous averaging in f/stop and footcandle /lux or f/stop and footlamberts are made possible.

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.

Specifications Subject to Change without Notice
SPOTMETER SUPPLIED WITH: Spectra Professional IV-A meter with Photosphere (for ambient light), Photodisc (for key or directional light), 1 degree PhotoSpot for (spotmeter readings), Leather carrying case and Hard carrying case, Neck-strap, 6-volt battery, Instructional manual and warranty card. Two-year limited warranty included.