Voltmaster IRT 1 Manuel D'utilisation page 27

i.e. at a distance of 100 cm, the measurement area is approx. 8.5 cm in size.
°C/°F switching
Using the "°C/°F" button, the temperature display can be switched
between °C and °F.
Emissivity
The instrument is set to emissivity of 0.95!
The emissivity is a value that is used to specify the energy radiation
characteristics of a material. The greater the value, the greater the capability
of the material to transmit radiation. Many organic materials and surfaces
have an emissivity of approx. 0.95. Metallic surfaces or shiny materials have
a low emissivity. More accurate measurement values can be obtained if the
measurement location is masked using black paint or adhesive tape.
Measurements cannot be carried out through transparent surfaces,
e.g. glass. Instead, the temperature of the surfaces of the glass area is
measured.
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