Wahl Heat Spy DHS520, User Manual

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User Manual Wahl DHS520
6.2 Lens Options
The Wahl DHS520/520B is supplied, as standard, with a protective window
which covers and protects the instrument lens.
Palmer Wahl can supply optional close-up lenses, which enable smaller
targets to be measured.
CAUTION
Never look at the sun through this instrument - this could cause
severe damage to the eye. When measuring temperatures above
1200°C/2192°F, a dark filter must be fitted to the lens assembly.
6.3 Fitting a Close-up Lens
To fit a close-up lens to the Wahl DHS520/520B thermometer, unscrew
the clear protection window from the lens assembly and replace it with the
relevant close-up lens.
The optical transmission characteristics of the protection window and the close-
up lens are similar. Therefore, there will be no significant calibration error, so
window compensation is not required.
6.4 Fitting a Dark Filter
When measuring temperatures above 1200°C/2192°F, the image through the
viewfinder is uncomfortably bright on the eye. To counter this effect, a dark
filter must be fitted in place of the clear protection window.
To fit a dark filter to the Wahl DHS520/520B thermometer, unscrew the clear
protection window from the lens assembly and replace it with the dark filter.
The optical transmission characteristics of the protection window and the dark
filter are similar. Therefore, there will be no significant calibration error, so
window compensation is not required.
6.5 Fitting a Dark Filter to a Close-up Lens
When measuring a small target where the temperature rises above 1200°C/
2192°F, the image through the viewfinder becomes uncomfortably bright on
the eye. A close-up lens and a dark filter combination must be fitted in place of
the clear protection window. (Continued...)