Luminantiemeter EC1-L

The Hagner EC1-L Screen Luminance and Film Density Meter is a compact instrument for measuring the luminance of luminous screens, for instance of film and slide viewers, X-ray viewers etc., and for easy calculation of film density. It has both an automatic zeroing and an on/off switch and the only controls needed are a four position range selection switch and a hold button to retain the displayed value.

The opening of the detector, which should be pressed against the screens, has a round aperture with an area of 100mm². The meter is normally calibrated to read from 1 cd/m² to 2,000,000 (2x10⁶) cd/m² in four measurement ranges.

This calibration is suitable for X-ray viewers. Other ranges, for instance from 0.1 - 200,000 cd/m² can be supplied on request.

The calculation of film density requires also a simple calculator which will give the logarithm to base 10 of a number (LOG10).

Measurement of film density

1. Measure the luminance (L_s) of the blank viewing screen and enter into the calculator.
2. Measure the luminance (L_f) of the film when placed over the screen.
3. Film density is then given by: D = LOG₁₀ (L_s/ L_f)

Example

Screen luminance is 1,352,000 cd/m²

Film luminance is 107.2 cd/m²

Density is D = LOG₁₀ (1,352,000/107.2)=4.1

If the value of screen luminance is stored in the memory of the calculator, the density at several different positions on the film can be calculated very easily.

Specifications