The low surface brightness (LSB) universe is one of the last frontiers in observational astronomy. However, uncovering the information contained in ultra-deep imaging is technically challenging. In this contribution, we present one of the fundamental tools of LSB astronomers: correcting for the extended Point-Spread Function (PSF), which is critical to characterize the LSB properties of astronomical images. We show how to build the extended PSF (approximately 5' in radius), in 5 bands (grizY), of one of the most important modern deep surveys: the Hyper-Suprime Camera (HSC) one on the 8.2 m Subaru telescope. These PSFs have been obtained by sampling individual point-like sources at different brightness. The techniques used here can be applied to the next generation of deep astronomical imaging surveys as the LSST.