Simulens Tab
The SimuLens system emulates several optical effects found in real-world camera lenses.
- Diffraction: Diffraction effects occur when light goes through small holes, causing interference patterns in the shape of the lens aperture. Light will always cause slight interference patterns because of the optical components used, causing the visual “artifact” known as glare. This setting controls the intensity of the diffraction effect.
- Frequency: Specifies the frequency of coloring in the diffraction effect. Higher values will make the patterns denser.
- Aperture Map: The shape of the diaphragm will model the pattern of light that reaches the film. For example, a circular diaphragm will create circular patterns; a hexagonal diaphragm will create 6 light streaks. You can set the diaphragm shape using a black & white or color map called the aperture map. The map should be black, with white specifying the shape and size of the aperture.
- Obstacle Map: Water drops, eyelashes or dirt on the camera lens will also cause diffraction effects. A black & white map called the obstacle map is needed. If you do not want to use an obstacle map, you can leave this path blank: you only need an aperture map for diffraction to work. However, if you do want to use an obstacle map, be aware that it is necessary to load an aperture map too. The map should be white, with black areas specifying dirt or scratches on the lens surface.
- Scattering: Commonly known as bloom, scattering occurs when the light is scattered inside the lens before reaching the film.
- Devignetting: Vignetting is an artifact that darkens an image around the edges, due to camera optics. Setting the devignetting parameter to 100% will eliminate the vignetting effect entirely; setting it to lower values will partially remove it. In the real world, the more wide-angle the lens is (for example, a focal length of 24mm), the more pronounced the vignetting will be. As you raise the focal length of the camera, the vignetting effect will be less pronounced. A focal length of around 80mm or higher will have almost no vignetting, no matter the Devignetting settings used.
Map Sizes
The obstacle map and the aperture map must have the same resolution. The rendered image and the aperture/obstacle maps do not necessarily need to have the same resolution, but the more similar they are in resolution, the less diffraction distortion you will get.
In most cases, you will NOT want to select the checkbox next to the three Simulens settings described above. Doing so adds unnecessary processing time to each sampling level update, and increases RAM usage during rendering. Instead, wait until the render has reached an acceptable SL for viewing the Simulens effect, stop the render, apply a Simulens effect to give you an idea of its influence, then disable Simulens again and resume the render. For adding Simulens effects to a range of MXI files after the render is completed, use File>MXI Batch Processing.