Thanks to creator Jon Arnold the creator of CameraSim, you can try out different focal lengths, aperture and other camera functions also available as an app for the Ipad see here http://camerasim.com/camerasim-ipad/
Try it below out below, by dragging the sliders
Learn more about the Camera sim as explained here. http://camerasim.com/slr-camera-explained/
Really great work here.