  Isomers produced by spontaneous fission of ${}^{252}$Cf have been measured
with the VESPA setup, composed of LaBr$_3$(Ce) detectors for fast $\gamma$-ray
spectroscopy and an ionization chamber for detecting fission fragments.
Identification of the isomers was derived from fission
fragment-$\gamma$-$\gamma$ coincidences. This paper presents the half-life of
34 isomeric states measured with this setup, from less than the nanosecond up
to tens of microseconds. Two of these isomers are reported for the first time,
in ${}^{108}$Tc and ${}^{147}$Ce. In addition to this half-life analysis, the
isomers are used to develop and test a nuclear charge calibration of the
ionization chamber.
