  To obtain an accurate description of broad-band photometric star cluster
evolution, certain effects should be accounted for, such as the preferential
loss of low-mass stars and the retain of stellar remnants. Moreover, the IMF
and metallicity affect photometry as well. Due to their advanced evolutionary
state, globular clusters (GCs) are interesting test cases for cluster models
describing these effects. In this paper we describe cluster models in which the
above effects are included. The photometric evolution of clusters is predicted,
and the results are applied to Galactic GCs. The presented cluster models
represent an analytical description of the evolution of the underlying stellar
mass function due to stellar evolution and dynamical cluster dissolution.
Stellar remnants are included by using initial-remnant mass relations, while
cluster photometry is computed from the Padova 1999 isochrones. Our study shows
that the preferential loss of low-mass stars, the retain of stellar remnants,
as well as IMF and metallicity variations strongly influence the magnitude,
colour and mass-to-light ratio evolution of clusters. The different effects can
be clearly separated with our models. The models are applied to the Galactic GC
population, of which the magnitude, colour and mass-to-light ratio ranges are
well reproduced. We also show that the mass-to-light ratios of clusters of
similar ages and metallicities cannot be assumed to be constant for all cluster
luminosities. Instead, mass-to-light ratio increases with cluster luminosity
and mass. These models underline the importance of detailed cluster models when
considering cluster photometry. With the analytic framework provided in this
paper, observed cluster properties can be interpreted in a more complete
perspective. (Abridged)
