Calibrated to measure the photopic response curve of the human eye, ideal for set, video, ambient and task lighting, lighting/contrast ratios, etc.
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SPECTRA CANDELA II and II-A
- How to measure lighting contrast
- How to convert footcandles to candelas
- Technical Specifications
- How to Purchase the Candela II or II-A
The Spectra Candela II and II-A are among the worlds most advanced and most sensitive exposure meters. Compact and easy to use, it provides an easy, economical means of making highly accurate measurements of indoor and outdoor light levels. Applications include set lighting, video lighting, task lighting, ambient illumination and calculation of lighting ratios.
While the Spectra Pro IV-A and Spectra Classic meters are calibrated to measure the spectral response of photographic film, the Spectra Candela meters are calibrated to measure the narrower photopic response curve of the human eye. Therefore, while the Spectra IV-A is most useful for photographic/video applications, the Spectra Candela II and II-A are most useful for industrial/scientific research applications.
The Spectra Candela II and II-A meters measure illuminance levels in footcandles or lux and instantly calculates the contrast ratio of your particular lighting situation. Illuminance is the scientific name for the measurement of incident light. The unit of measurement is commonly the "footcandle" in the English system and the "lux" or "dekalux" (lux times 10) in the metric system.
The Spectra Candela meters are designed for simple, one handed convenience. Simply pressing one push-button enables the light level to be measured and displayed on the easy to read back-lit LCD. It reads out directly from 0.1 to 70,000 footcandles and 1 to 100,000 lux - a range encompassing illumination levels from dim indoor lighting to bright sunlight. The meter can store and recall up to two readings with the memory/recall function and covers a sensitivity range of almost one-million to one.
Lighting contrast is defined as the ratio of the illumination produced by the key light plus fill light to that produced by the fill light alone. While the exact value of lighting contrast for a particular scene is a matter of personal choice, the following range of values are commonly suggested: color films: 1.5:1 to 5:1, black and white films: 2:1 to 16:1.
Note: The main difference between the Spectra Candela II and Candela II-A meters is the Candela II-A can automatically calculate contrast ratios as well as average footcandles and lux.
The Candela II and II-A are a "must" for set lighting, video lighting, task lighting, ambient illumination and calculation of lighting ratios.
Electroluminescent Backlit Display: Bright green E-L Lamp for reading displayed measurements at very low light levels.
Instant Recall of Measurement (Candela II-A only): Pressing the Recall (RCL) switch will recall the previously stored reading and display it with the "MEM" announciator on the lcd. Activating the "RCL" switch again will store the recalled information back into memory and display the last reading taken.
Accuracy: The Spectra Candela II is a highly accurate meter designed and manufactured for industrial/scientific research.
How to measure lighting contrast:
1. Prepare the meter for the measurement of illuminance by switching the sliding switch to ILLUM.
2. Point the meter, from the subject, directly at the key plus fill light. Take a reading and store it in the meter's memory (in all readings, be careful your own shadow does not fall on the meter).
3. Point the meter, from the subject toward the fill light or reflectors (exclude the key light) and adjust the fill light or reflectors until the required light level is reached.
4. You can alternate between the stored key light and the fill light reading by toggling the memory "RCL" switch.
Candelas are equal to the square of the distance multiplied by the number of footcandles. For example, if your meter is ten feet away from the light source and your meter reading is 10 footcandles, the equivalent candelas equals 10 feet squared (e.g. 100) times 10 -- which equals 1,000 candelas.
How to convert footcandles and lux to candelas:
The conversion of footcandles and lux to candelas is most accurately achieved in the context of a single point source of light measured in the dark. If the light source is diffused, you should take several readings at different angles in order to calculate an "average" candela measurement.
TYPE: The Spectra Candela II for measuring Incident and Reflected Light.
TECHNOLOGY: Utilizes advanced Custom Sealed Hybrid electronic circuitry, Multiple Range Linear Circuit (MRLC) controlled by Advanced microcomputer and custom liquid crystal display.
LIGHT SENSOR: Silicon Photovaltaic cell, Computer selected glass filters tailored to spectral response of the film. Swivel head assembly turns 270 degrees.
MEASURING CAPABILITY: Direct readout of illuminance level in footcandles (fc) and lux (lx)
MEASURING RANGE: One million to one direct reading Multiple Range Linear Circuit controlled by microcomputer.
ILLUMINANCE: Footcandles 0.1 - 70,000 and Lux 1 - 100,000.
RESOLUTION: 0 - 50 footcandles in 0.1 footcandle increments; 50 - 1,000 footcandles in 1 footcandle increments; 1,000 - 70,000 footcandles in 10 footcandle increments.
ACCURACY: +/- 5%. Calibration is traceable to National Institute Of Standard Technology (NIST), Washington, DC.
ADDITIONAL FUNCTIONS: Memory Store and Recall.
LAMP: Electroluminescent lamp (optional) for backlit liquid crystal display.
POWER CONSUMPTION: Operating 5.00 mA/Reading. Data Retention 5uA.
POWER SOURCE: One 6 volt battery no's: A544, PX28L, PX28.
ESTIMATED BATTERY LIFE: Approximately one year with normal use.
DIMENSIONS: 5-1/2" X 2-1/2" X 2"
WEIGHT: Approximately 6 ounces
WARRANTY: One year limited warranty
RECOMMENDED RE-CALIBRATION PERIOD: Every six to twelve months (six months for meters stored in high humidity environments)
SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE
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