  We investigate the effect of gravitational lensing on the farthest known
supernova, SN1997ff. The SN was found at z~1.7 in the Hubble Deep Field North
and is most likely of Type Ia. Due to our poor knowledge of the properties of
the lensing foreground galaxies, we conclude that large magnification effects
are possible for reasonable lens parameter values implying that this single SN
does not put any strong constraints on the cosmological parameters, grey dust
obscuration or luminosity evolution of SNIa until we can model the lensing with
high accuracy.
