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Introduction

In comparison with spectroscopy of extended extragalactic objects, the task of observing stars with a high spectral resolution is traditionally given lower priority. The reason is fundamental: in spectroscopy of extended objects the limiting magnitude is proportional to the squared telescope mirror diameter, whereas in high spectral resolution spectroscopy of stars (i.e. when the angular diameter of the turbulent disk of a star is larger than the spectrograph slit width) the limiting magnitude is proportional to the telescope mirror diameter. A ``natural'' response of some researchers of stars and starlike objects is preferential use of low and moderate spectral resolution techniques, where one succeeds in minimizing losses at the spectrograph input. However, over the last decade new problems of spectroscopy of cool stars, interstellar and intergalactic medium, mapping of stars' surfaces, search for low-mass companion stars have been posed and being solved. All these problems are limiting for large telescopes, that is why the development of high-resolution spectroscopy facilities at large telescopes is of great concern. Suffice it document to mention that the first device put into operation at the 10 m Keck telescope is the high-resolution echelle spectrograph HIRES (Fogt et al., 1994). In order to show how the achievements in technology of manufacturing solid-state light detectors and the development of cross-dispersion spectral systems alter psychology of a spectroscopist, we now present some considerations on the relationship of principal characteristics determined in the process of observations.