  We present IR surface brightness fluctuation (SBF) distance measurements to
NGC 4889 in the Coma cluster and to NGC 3309 and NGC 3311 in the Hydra cluster.
We explicitly corrected for the contributions to the fluctuations from globular
clusters, background galaxies, and residual background variance. We measured a
distance of 85 +/- 10 Mpc to NGC 4889 and a distance of 46 +/- 5 Mpc to the
Hydra cluster. Adopting recession velocities of 7186 +/- 428 km/s for Coma and
4054 +/- 296 km/s for Hydra gives a mean Hubble constant of H_0 = 87 +/- 11
km/s/Mpc. Corrections for residual variances were a significant fraction of the
SBF signal measured, and, if underestimated, would bias our measurement towards
smaller distances and larger values of H_0. Both NICMOS on the Hubble Space
Telescope and large-aperture ground-based telescopes with new IR detectors will
make accurate SBF distance measurements possible to 100 Mpc and beyond.
