The. Spectra, Professional IV-A measures incident and reflected light intensity directly in f/stops, footcandles or lux and instantly calculates f/stop, difference, contrast ratio. and average of your particular lighting situation, This feature is a Spectra exclusive.
The Spectra Professional IV-A 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 increments. Both are displayed simultaneously on a backlit liquid crystal display, along with film-speed, frames per second for cine use or exposure time for still photography.
The Spectra Professional IV-A is designed to measure highly accurate light intensity and covers luminance levels from 0.1 to 70,000 footcandles and 1 to 100,000 luxes. The meter covers a sensitivity range of almost one million to one!