  We present time-resolved photometry of the optical counterpart to the black
hole candidate Swift J1753.5-0127, which has remained in the low/hard X-ray
state and bright at optical/IR wavelengths since its discovery in 2005. At the
time of our observations Swift J1753.5-0127 does not show a decay trend but
remains stable at R=16.45 with a night to night variability of ~0.05 mag. The
R-band light curves, taken from 2007 June 3 to August 31, are not sinusoidal,
but exhibit a complex morphology with remarkable changes in shape and
amplitude. The best period determination is 3.2443+-0.0010 hours. This
photometric period is likely a superhump period, slightly larger than the
orbital period. Therefore, Swift J1753.5-0127 is the black hole candidate with
the shortest orbital period observed to date. Our estimation of the distance is
comparable to values previously published and likely places Swift J1753.5-0127
in the Galactic halo.
