  Speckle photography can be used to monitor deformations of solid surfaces.
The measuring characteristics, such as range or lateral resolution depend
heavily on the optical recording and illumination set-up. This paper shows how,
by the addition of two suitably perforated masks, the optical aperture of the
system may vary from point to point, accordingly adapting the range and
resolution to local requirements. Furthermore, by illuminating narrow areas,
speckle size can be chosen independently from the optical aperture, thus
lifting an important constraint on its choice. The new technique in described
within the framework of digital defocused speckle photography under normal
collimated illumination. Mutually limiting relations between range of
measurement and spatial frequency resolution turn up both locally and when the
whole surface under study is considered. They are deduced and discussed in
detail.
