A manual device for the detection of photometric data which includes a measuring head to illuminate a measuring surface and to detect the light reflected. The measuring light captured by the measuring head is spectrally decomposed by a monochromator containing a diffraction grating. The intensity of the light exiting through an outlet diaphragm is detected by a photodetector. The spectral position of the measuring light is set by a drive motor rotating a grating shaft connected with the holder of the diffraction grating. From the spectra detected, densitometric and colorimetric data are calculated by a computer, which together with the spectra determined, may be displayed on a display field.