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We propose to image in the MIR the center of three galaxy clusters showing a large population of arc(let)s, with redshifts inferred either from spectroscopy or from the lensing inversion. The aim is to benefit of magnification to study galaxy evolution of faint distant field galaxies, by constraining their star formation and their metal enrichment histories. Similar analyses will be done simultaneously in a subsample of galaxies with lower redshift evolving in rich environments (clusters). We can reach both goals with a minimum cost, because lensing clusters are natural gravitational telescopes that magnify the back- ground galaxies. The lensing inversion and spectroscopic surveys show that the lensed galaxies detected as giant arcs or arclets have a mean redshift between 0.7 and 1. But, acording to the optical and near-IR data presently available, some of the giant arcs have redshifts larger than 2.5 (as in Cl2244-02 or Cl00- 24+17). Thus, this program will permit to compare 3 populations of galaxies: the nearby cluster galaxies (z around 0.3), the distant magnified galaxies (z around 1) and some highly magnified very distant galaxies (z>2.5). A great effort is presently in progress to investigate spectroscopically the population of galaxies with B=22-25, using the largest ground-based telescopes. Nevertheless, photometry is the only way to study the spectral energy distribu- tion of fainter objects, in order to determine the permitted regions in the relevant parameter space: age, present SFR and SFR history, metallicity and dust. The arc(let)s population is the faint extension of the spectroscopic sample (B=25-27). About 2/3 of them, at z around 1, is expected to experience an active star formation and to be dust enshro so that a major part of their emission appears in the IR. The ratio of the MIR luminosity to the blue lumino- sity will be used to constrain their present SFR and their star formation his- tory. Thus, we should be able to estimate the stellar and the dust content of these faint galaxies. The morphology of the arclets observed either on images obtained at CFHT or with HST provides a priori knowledge for ISOCAM, to reach a better spatial resolution after deconvolution.