The Spectra® Professional® IV-A model # 18002-A is an Advanced Digital Exposure Meter for motion picture video and digital photography lighting. This Internationally Acclaimed Industry Standard has received Technical Academy (OSCAR), Engineering Emmy and numerous international awards.The Spectra Professional IV-A is compact and easy to use, it is the most comprehensive, and reliable light meter for motion picture, digital photography and video lighting. See Pro IV-A Detailed Description.Spectra meters are the industry standard and choice of professionals for the past 60 years.SPECIFICATIONS:MEASURING RANGE: One million to one (20 f/stop) direct reading Multiple Range Linear Circuit. Digital f/stop: f/0.35 to f/128 in 1/10-stop increments. Analog f/stop: f/0.7 to f/45 in 1/3-stop increments. PHOTOGRAPHIC ILLUMINANCE: Footcandles 0.1 to 70,000 and lux 1 to 100,000. CONTRAST RATIOS: Calculates ratio of key plus fill to fill light alone from 1:1 to 999:1. F-STOP DIFFERENCE: Displayed in precise 1/10-stop increments up to Plus or Minus 12 f/stop. AVERAGE: Average of two readings and or continuous averaging in f/stop and footcandle mode. DISPLAY RANGE: ISO 3 to ISO 8,000 in 1/3-stop increments. FRAMES PER SECOND: 2 to 360 (for motion picture cameras). EXPOSURE TIME: 1/8000 sec to 30 minutes. ADDITIONAL FUNCTIONS: Memory Recall switch is to recall stored reading in memory (M1), current reading in memory 2(M2) and/or the Ratio, Average and f/stop difference of the two readings. LAMP: Electroluminescent lamp for backlit liquid crystal display. POWER SOURCE: One 6 volt battery.ESTIMATED BATTERY LIFE: Approximately one year with normal use.ALL SPECTRA PROFESSIONAL VI-A METERS ARE SUPPLIED WITH :• Photoshere (for ambient light)• Photodisc (for key or directional light)• Leather carrying case• Neck-strap• 6-volt battery• Instructional manual and Warranty card