Rangefinder cameras are very cumbersome to use with polarisers. Kenko's Vernier polariser filters have a graduated scale on them, which is the key to their usefulness, the numeric scale corresponds exactly with those on the polariser finder and polariser checker filters.
This system consists of three parts: Vernier polarising filter, a hotshoe mounted polariser finder, and a polariser filter checker. All feature the engraved graduated numeric scale.
The polariser position required for a particular shot can be previewed using either the handheld polariser checker filter (recommended for view cameras) or the hotshoe mounted polariser finder.
The position can be read off from the graduated numeric scale against the index mark (or the number is at the top i.e. 'midday' position of the polariser checker filter).
The Vernier polariser fitted to the lens is then rotated so that the position corresponds to number found on the preview polariser. The polariser is now correctly set for the shot as previewed at the start.