A monochrome CCD is recommended as detector. Color cameras have a Bayer matrix in front of the pixels. These are color filters (RGB) arranged in a regular pattern so that each pixel „sees“ only one color component. In other words, around 2/3 of the light is absorbed in the filters and is thus lost. Color cameras therefore do not have the efficiency of monochrome cameras.
The size of the CCD chip determines the wavelength window that is imaged on it. On the other hand, the sharp field of view imaged by the optics of the spectrograph is limited. There is therefore a limit to the maximum size of the detector. In most cases a detector of the Txp KAF-1603ME CCD 1536 x 1024 pixels à 9×9 um, max. QE above 80% (approx. 14 mm x 9 mm), no microlensing, is a good compromise.