Hagner ScreenMaster
The Hagner ScreenMaster is a small, handy and very easy-to-use instrument for
measurement of luminance as well as illuminance over a range of 0.1-200,000 cd/m²
and lux, respectively. With both automatic zeroing and on/off switch, the only controls
needed are a four-position range selection switch, a hold button for retaining the
displayed value and a switch for selection between luminance and illuminance.
The ScreenMaster is provided with two detectors, which both are carefully filtered to
give a spectral response close to that of the human eye, as defined in CIE standards.
The detector on the front side of the instrument is well cosine corrected and used for
measurement of illuminance, for instance on computer screens and in working areas.
The detector on the underneath side of the instrument is built into a tube and is
used for measurement of luminance. The opening of the tube (= 1 cm²) gives a
measuring angle of 36°. (The measured area = the base of a cone with a 36° top
angle.) This implies that the instrument is well suited for e.g. determination of
luminaces and contrasts on computer screens, background luminances and
luminances from negativ viewing tables. (To avoid reflectance of ambient light the
detectortube can be pressed against the light emitting surface when measuring on
screens and tables.) By means of this detector it is furthermore possible to caculate
transmission factors and film density.
The Hagner ScreenMaster is of course also most suitable for general evaluations of
lighting quality.
Operation
To open the lid, press the forward part lightly downward with your thumb and at the
same time pull the latch upwards with the first two fingers of the same hand. The
instrument comes on when the cover is opened and turns off when it is closed. Set the
luminance/illuminance switch in desired position. Move the range switch to the range
which will give the greatest accuracy and read the display. When the HOLD button is
pressed the measured value will show on the display until the button is released.
Calibration
The instrument is carefully calibrated when delivered. As the light sensitive silicon
diodes are extremely stable over long periods of time recalibration every two-three
years should, under normal use of the instrument, be sufficient. If however there is any
reason to believe that the instrument is out of calibration, it can be returned to your
stockist or the manufacturer for earlier control checks.