  Optical CCD imaging and spectroscopic observations of three supernova
remnants are presented. Optical emission from G 54.4-0.3 and G 59.8+1.2 is
detected for the first time, while the first flux calibrated CCD images of the
supernova remnant G 126.2+1.6 were performed in the optical emission lines of
Halpha+[N II], [O III] and [S II]. A mixture of filamentary and diffuse
structures is observed in G 54.4-0.3 and G 59.8+1.2, mainly in Halpha+[N II],
while the deep optical images of G 126.2+1.6 reveal several new filamentary and
diffuse structures inside the extent of the remnant as defined by its known
radio emission. In all cases, the radio emission is found to be well correlated
with the optical filaments. [O III] emission was not detected at G 54.4-0.3 and
G 59.8+1.2 while in G 126.2+1.6, significant morphological differences between
the low and medium ionization images are present suggesting incomplete shock
structures. Deep long-slit spectra were taken at different positions of the
remnants. Both the flux calibrated images and the long-slit spectra clearly
show that the emission originates from shock-heated gas, while some spectra of
G 126.2+1.6 are characterized by large [O III]/Hbeta ratios. This remnant's [O
III] flux suggests shock velocities into the interstellar "clouds" between 100
and 120 km/s, while the [O III] absence in the other two remnants indicates
slower shock velocities. For all remnants, the [S II]6716/6731 ratio indicates
electron densities below 600 cm^{-3} with particularly low densities for G
54.4-0.3 (below 50 cm^{-3}). Finally, the Halpha emission has been measured to
be between 3.0 to 15.2x10^{-17} erg/s/cm^2/ arcsec^2, 3.2x10^{-17} erg/s/cm^2/
arcsec^2 and between 6.5 to 16.8x10^{-17} erg/s/cm^2/ arcsec^2 for G 54.4-0.3,
G 59.8+1.2 and G 126.2+1.6, respectively.
