Japanese optical manufacturer Tokina is showing a hydrophilic filter coating that forces water droplets to spread into a thin film so that they become invisible to the camera. The coating will allow photographers to carry on shooting when rain or spray on the lens would otherwise obstruct the optical path.

For now the coating has been applied to thick clear glass that is intended to be used as a protective screen in front of other filters or the lens front element, but Tokina's general manager for the international department, Masatoshi Itoh, told DPReview that if the coating proves successful the company may add it to other filters.

The idea is that landscape photographers and videographers working in wet conditions will be able to use this coated 'filter' to act as a shield. The hydrophilic properties of the coating disperse water that lands on the coated surface, so the uneven effects caused by droplets are eliminated. Water will transform from droplets to a thin film that can be looked through with no visible consequences.

The hydrophilic coating is applied on top of a photo catalytic layer which needs regular exposure to ultraviolet light. On first use the filter needs about four hours of sunlight to create the hydrophilic characteristic, but the effect is maintained for about 48 hours. When the coating is active the filter is easy to clean, but a build-up of dirt and dust can reduce its effectiveness. The protector will be available in screw sizes from 77-127mm, and 4x4-inch and 4x5.65-inch sheets.

Tokina also intends to introduce a series of infrared-limiting neutral density filters. Available in screw and square formats, the company will bring ND0.3, 0.6, 0.9 and 1.2 strengths to the market in April 2015, with ND1.5, 1.8 and 2.1 models arriving in September. The filters will be available in 82-127mm thread sizes, as well as 4x4-inch and 4x5.65-inch sheets. Mr Itoh said he would 'consider' bringing them out in a 77mm thread, which would make sense as Tokina has 77mm lenses.

A variable ND filter will also be introduced in September, with a range of ND2.5-400 and sizes from 82-127mm, along with a combined neutral density and polariser filter with strengths from ND0.3-1.2.

Pricing for the hydrophilic protector will start at £299 for a 77mm screw thread model, while the IR-cut ND filters will be priced from £130 for the 82mm screw ND0.3 version. For more information visit the Tokina website.