In Jülich, a small-angle neutron scattering instrument and neutron reflectometer will be built, both of them use a double-focusing mirror, which produces an one-to-one image of the entrance on the detector. This neutron focusing technique, known since 50 years, has become practicable only recently, since very smooth mirror surfaces were produced for X-ray space telescopes. The neutron mirrors are produced by the same technique. The focusing is especially good for high-resolution experiments (with the momentum transfer Q<10−3 Å−1). Compared to pinhole collimation, the focusing technique in this region has intensity advantages of several orders of magnitude. In this contribution mainly the influence of the shape of the mirror and the influence of gravity on the quality of the image is discussed. We explain, how these effects can be minimized.