The other way is creating an opaque tube with a thin slit at one side, and the other side is assembled to the camera lens where the diffraction grating is placed with adhesive tape (figure 4). With this we eliminate the problem of the dispersion of light around the slit, providing beautiful photos of spectra even in the presence of daylight. It has also the advantage to require the calibration procedure only once. The slit aperture must be narrow enough to resolve the spectral lines detected by the camera. The width of the lines is important in determining