  We address the pair of conjugated field modes obtained from
parametric-downconversion as a convenient system to analyze the
quantum-classical transition in the continuous variable regime. We explicitly
evaluate intensity correlations, negativity and entanglement for the system in
a thermal state and show that a hierarchy of nonclassicality thresholds
naturally emerges in terms of thermal and downconversion photon number. We show
that the transition from quantum to classical regime may be tuned by
controlling the intensities of the seeds and detected by intensity
measurements. Besides, we show that the thresholds are not affected by losses,
which only modify the amount of nonclassicality. The multimode case is also
analyzed in some detail.
