Slashcam refer to the crop as being in the specification  "The Sigma fp will be equipped with a 35mm Bayer sensor with 24.6 effective MP exposed at the back (so not with a Foveon sensor like the Sigma Quattro). In the technical data for the camera, however, a crop of 1.5 is mentioned, which will most likely be effective in film mode." If you look at the specification, the crop (or Clop as its spelt in the document  ) is actually mentioned in reference to still formats rather than video