Render-optimization is an important phase of the light field rendering process to improve user experience while minimizing computational effort. It is concerned with CPU/GPU interplay, and requires both an understanding of optics and the equations behind the light field. In this study we investigate users evaluation of light field rendering for a head mounted display by comparing images created with different methods. Images made with high-precision but cost heavy methods arecompared to images made with improved algorithms, in order to test users' ability to perceive a difference. We implement an improved method for light field rendering, where we instead of rendering all virtual cameras for each subimage instead render the four corner cameras and interpolate the rest of the views using pixel reprojection in the game engine Unity 3D.