Nokishita reports that Canon’s next lens will be a smaller, cheaper version of the well-reviewed RF 15-35mm f/2.8, increasing the zoom range on the wide end by one millimeter and slimming it down to a f/4 maximum aperture.
The Canon RF 14-35mm f/4 L will still be considered a top-of-the-line instrument, earning the red ring status of the L series.
The release of the 15-35mm f/2.8 heralded a new era for mirrorless-first designed lenses that took advantage of shorter a flange distance to deliberately improved on EF designs. The wide zoom made explicit that Canon RF mount users would see benefits such as, in this case, an extra degree of field of view at the wide end. The EF equivalent lens series never surpassed 16mm at the wide end.
Since lens design is a series of compromises between capabilities, Canon opted with the RF mount f/2.8 version to concentrate the new, more capacious, design envelope to improve focal length and image quality. The upcoming f/4 version appears to concentrate further on the focal length, which may imply that slimming the lens down in size may have been less of a priority. The f/2.8 version is already quite manageable in size.