A new instrument, a camera obscura with a number of light apertures (or slits), is suggested for observation of EAS images in Cerenkov light. Its advantages (over mirror-imaging telescopes) are a low night-sky light noise, a wide field of view and absence of aberrations. This camera is effective for measurements of bright objects such as EAS of energies higher than 10³ TeV. Analysis of EAS images in the 'knee' region of the primary cosmic-ray energy spectrum (E₀ approximately=3*10³ TeV) could give new information on the expected variation of cosmic-ray composition in this energy region.