  We present BVRI photometry and optical spectroscopy of SN 2005bf near light
maximum. The maximum phase is broad and occurred around 2005 May 7, about forty
days after the shock breakout. SN 2005bf has a peak bolometric magnitude
M_{bol}=-18.0\pm 0.2: while this is not particularly bright, it occurred at an
epoch significantly later than other SNe Ibc, indicating that the SN possibly
ejected ~0.31 M_{sun} of 56Ni, which is more than the typical amount. The
spectra of SN 2005bf around maximum are very similar to those of the Type Ib
SNe 1999ex and 1984L about 25-35 days after explosion, displaying prominent He
I, Fe II, Ca II H & K and the near-IR triplet P Cygni lines. Except for the
strongest lines, He I absorptions are blueshifted by <~6500 km/s, and Fe II by
\~7500-8000 km/s. No other SNe Ib have been reported to have their Fe II
absorptions blueshifted more than their He I absorptions. Relatively weak
H-alpha and very weak H-beta may also exist, blueshifted by ~15,000 km/s. We
suggest that SN 2005bf was the explosion of a massive He star, possibly with a
trace of a hydrogen envelope.
