  Using single channel infrared photometry from the literature, a provisional
K-band diameter--velocity dispersion relation for elliptical galaxies in the
Coma and Virgo clusters is derived. The Coma cluster relation has \~1.5 times
lower scatter at K than in B or V. Excluding 4 outliers, the RMS scatter at K
for 24 galaxies in Coma is only 4.8% in distance, close to the limit implied by
the observational errors. Distance estimates based on the IR \Dsig relation
will be more accurate than those derived from optical data. The improvement in
the infrared is attributed to a decrease in sensitivity to stellar population
parameters (age, metallicity, and slope of the IMF) as well as lower internal
extinction from dust compared to the optical. That the \Dsig relation has a
larger scatter in the optical indicates that there are detectable, but small,
stellar population or dust content differences among the Coma ellipticals.
Since the \Dsig relations are based on the fundamental plane, this result
promises that the fundamental plane is thinner in the infrared than it is in
the optical.
  Infrared photometric data available for Virgo are limited to just 13 objects;
the spread in distance due to the depth of the cluster precludes any
significant improvement over B and V. A relative Coma-Virgo distance of 5.56 is
derived from the K band data, in agreement with estimates in other colors and
using other techniques, indicating that there is no significant age difference
between Virgo and Coma ellipticals.
