  The Lanczos method of Cullum and Willoughby is studied for euclidean Wilson
fermions in quenched and unquenched SU(2) gauge fields on lattices of volume
ranging from $4^4$ to $16^4$. The method is reliable even on larger lattices,
but its cost for the computation of a given fraction of the spectrum grows
(approximately) with the square of the lattice volume. We investigate the
convergence behaviour and show that it is closely linked with the local
spectral density. Complete spectra are determined on lattices up to $8^3 \cdot
12$. For configurations where all eigenvalues are computed, we give numerical
values for the fermionic determinants and results for spectral densities.
Determinants are also given for staggered fermions whose quenched and
unquenched spectra were studied in a previous publication.
