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Close-up lenses for model S5
The Hagner S3, S4 and S5 Universal Photometer can be provided with close-up lenses for measuring the luminance of small surfaces at short distance without troublesome light loss. The lenses are available in sets of 3 and can be used separately or in combination with each other.
For the Hagner Universal Photometer, model S3 and S4
Measuring the luminance of small surfaces
The Hagner Universal Photometer can be provided with close-up lenses for measuring the luminance of small surfaces at short distances, for example text on data terminal screens, without troublesome light loss.
The close-up lenses are available in sets of 3:
A. Focal length 500 mm (2 dioptres)
B. Focal length 250 mm (4 dioptres)
C. Focal length 125 mm (8 dioptres)
The lenses can be used separately or in combination with each other.
The following table applies when using close-up lenses with the Hagner Universal Photometer, model S3, S4 and S5
When close-up lenses are used, the lumiance (L) of the object is obtained from the following equation:
L = F x LM where F is the correction factor from the above table and LM
is the luminance measured with the close-up lense mounted.
It should be noted that the luminance (L) is the average luminance of a cone with the object on the "top" and the surface of the outermost lens as a base.