  The pixel-to-pixel spectral fitting technique is often used in studies of
stellar populations. It enables the user to infer several parameters from
integrated light spectra such as ages and chemical abundances. In this paper,
we examine the question of how the inferred parameters change with the choice
of wavelength range used. We have employed two different libraries of
integrated light spectra of globular clusters (GCs) from the literature and
fitted them to stellar population models using the code Starlight. We performed
tests using different regions of the spectra to infer reddening, ages, [Fe/H]
and [alpha/Fe]. Comparing our results to age values obtained from isochrone
fitting and chemical abundances from high resolution spectroscopy, we find
that: (1) The inferred parameters change with the wavelength range used; (2)
The method in general retrieves good reddening estimates, specially when a
wider wavelength range is fitted; (3) The ideal spectral regions for
determination of age, [Fe/H], and [alpha/Fe] are: 4170-5540A, 5280-7020A, and
4828-5364A, respectively; (4) The retrieved age values for old metal-poor
objects can be several Gyr younger than those resulting from isochrone fitting.
We conclude that, depending on the parameter of interest and the accuracy
requirements, fitting the largest possible wavelength range may not necessarily
be the best strategy.
