  The ESO-Spitzer extragalactic Imaging Survey (ESIS) is the optical follow up
of the Spitzer Wide-Area InfraRed Extragalactic (SWIRE) survey in the ELAIS-S1
area. This paper presents B, V, R Wide Field Imager observations of the first
1.5 square degree of the ESIS survey. Data reduction is described including
astrometric calibration, illumination and color corrections, completeness and
photometric accuracy estimates. Number counts and color distributions are
compared to literature observational and theoretical data, including
non-evolutionary, PLE, evolutionary and semi-analytic Lambda-CDM galaxy models,
as well as Milky Way stellar predictions. ESIS data are in good agreement with
previous works and are best reproduced by evolutionary and hierarchical
Lambda-CDM scenarios. The ELAIS-S1 area benefits from extensive follow-up from
X-ray to radio frequencies: some potential uses of the multi-wavelength
observations are illustrated. Optical-Spitzer color-color plots promise to be
very powerful tools to disentangle different classes of sources (e.g. AGNs,
starbursts, quiescent galaxies). Ultraviolet GALEX data are matched to optical
and Spitzer samples, leading to a discussion of galaxy properties in the
UV-to-24 microns color space. The spectral energy distribution of a few
objects, from the X-rays to the far-IR are presented as examples of the
multi-wavelength study of galaxy emission components in different spectral
domains.
