  This is the first in a series of papers on the weak lensing effect caused by
clusters of galaxies in Sloan Digital Sky Survey. The photometrically selected
cluster sample, known as MaxBCG, includes ~130,000 objects between redshift 0.1
and 0.3, ranging in size from small groups to massive clusters. We split the
clusters into bins of richness and luminosity and stack the surface density
contrast to produce mean radial profiles. The mean profiles are detected over a
range of scales, from the inner halo (25 kpc/h) well into the surrounding large
scale structure (30 Mpc/h), with a significance of 15 to 20 in each bin. The
signal over this large range of scales is best interpreted in terms of the
cluster-mass cross-correlation function. We pay careful attention to sources of
systematic error, correcting for them where possible. The resulting signals are
calibrated to the ~10% level, with the dominant remaining uncertainty being the
redshift distribution of the background sources. We find that the profiles
scale strongly with richness and luminosity. We find the signal within a given
richness bin depends upon luminosity, suggesting that luminosity is more
closely correlated with mass than galaxy counts. We split the samples by
redshift but detect no significant evolution. The profiles are not well
described by power laws. In a subsequent series of papers we invert the
profiles to three-dimensional mass profiles, show that they are well fit by a
halo model description, measure mass-to-light ratios and provide a cosmological
interpretation.
