In this work we discuss the detection of Ly-α emitters (LAEs) through the gravitational amplification effect due to the mass in the core of the cluster of galaxies MS~2053.7-0449. We modeled the cluster using two NFW profiles, and 23 Galaxy-scale mass components as perturbations to the cluster potential. We simulate a distribution of sources for different redshifts. The positions and magnifications in the image plane were calculated. Finally, we estimated the probability to detect images from Ly-α emitters with the OSIRIS-GTC tunable filters. The instrument OSIRIS (Optical System for Imaging and Low Resolution Integrated Spectroscopy) is an imaging system and a low-resolution long-slit and multi-object spectrograph for the Gran Telescopio de Canarias (GTC). The image capabilities of OSIRIS include both broad band and tunable filters (TF). The TF provides the capability of making narrowband imaging choosing the central wavelength and the bandpass of the filter.