Estimating depth from a single RGB images is a fundamental task in computer vision, which is most directly solved using supervised deep learning. In the field of unsupervised learning of depth from a single RGB image, depth is not given explicitly. Existing work in the field receives either a stereo pair, a monocular video, or multiple views, and, using losses that are based on structure-from-motion, trains a depth estimation network. In this work, we rely, instead of different views, on depth from focus cues. Learning is based on a novel Point Spread Function convolutional layer, which applies location specific kernels that arise from the Circle-Of-Confusion in each image location. We evaluate our method on data derived from five common datasets for depth estimation and lightfield images, and present results that are on par with supervised methods on KITTI and Make3D datasets and outperform unsupervised learning approaches. Since the phenomenon of depth from defocus is not dataset specific, we hypothesize that learning based on it would overfit less to the specific content in each dataset. Our experiments show that this is indeed the case, and an estimator learned on one dataset using our method provides better results on other datasets, than the directly supervised methods.Our method relies on a novel Point Spread Function (PSF) layer, which preforms a local operation over an image, with a location dependent kernel which is computed "on-the-fly", according to the estimated parameters of the PSF at each location. More specifically, the layer receives three inputs: an all-in-focus image, estimated depth-map and camera parameters, and outputs an image at one specific focus. This image is then compared to the training images to compute a loss. Both the forward and backward operations of the layer are efficiently computed using a dedicated CUDA kernel. This layer is then used as part of a novel architecture, combining the successful ASPP architecture [5,9]. To improve the ASPP block, we add dense connections [16], followed by self-attention [42].We evaluate our method on all relevant benchmarks we were able to obtain. These include the flower lightfield dataset and the multifocus indoor and outdoor scene dataset, for which we compare the ability to generate unseen focus arXiv:2001.05036v1 [cs.CV]