The low surface brightness Universe is one of the latest frontier in observational Astronomy. However, uncovering the precious information contained in ultra-deep imaging is technically challenging. In this contribution, we will present one of the fundamental tools in the toolbox of low surface brightness astronomers: the extended Point Spread Function (PSF). Having an extended PSF is fundamental to characterize the low surface brightness properties of astronomical objects like the extended stellar halos, colors, structural properties, etc. We show the first results in the estimation of extended PSFs of one of the most important nowadays deep surveys: the Hyper-Suprime Camera (HSC) on the 8.2-m Subaru telescope. The techniques used here to build the PSFs can be applied to the next generation of deep imaging astronomical surveys as the LSST.