In this work we perform the first test of a stellar spectral classification method ( Stock & Stock 1999 ) by applying it to early type stars .
The sample of stars are the members of the open cluster IC 2391 that have high-resolution spectra available in the UVES Project of Paranal Observatory .
We show that , in general , absolute magnitudes M _ { V } and intrinsic colors ( B - V ) _ { 0 } can be recovered within the uncertainties stated in the original calibration ( \sim 0.4 for the magnitudes and \sim 0.03 for the colors ) .
This accuracy allows us to estimate distances and to infer membership of individual stars to obtain an average distance to the cluster of 156 \pm 24 pc , which is in good agreement with previous reported determinations .
Finally , we identify and discuss the real strengths and limitations of this method and we suggest how it can be improved for future studies .