Pentax is set to launch a new 25mm lens, specifically designed for its 645D medium-format DSLR. It is due to go on sale in mid-April, priced a penny under £4,000.

The launch comes a year after the release of a film and digital version of the lens carrying the same specification, which will now be available in Japan only, according to Pentax.

A Pentax UK spokesman explained that by making a digital-only version the firm hopes to ramp up production for the 25mm, which he said has proved popular.

The new lens should be quicker to manufacture than its film and digital sibling, said the spokesman.

However, it will be £200 more expensive than the current ?Pentax-D FA? version which went on sale last April priced £3,799.99.

Pentax attributes the price difference to currency changes over the past 12 months.

The Pentax-DA645 25mm f/4 AL [IF] SDM AW is billed as an ultra-wide lens featuring a dust-proof and weather-resistant build.

It is designed to deliver the 35mm viewing angle equivalent of a 19.5mm optic.

The lens includes Quick-Shift focus, designed for ?instant switching to manual-focus operation, after the subject is captured in focus by the AF system?.

It boasts 11 seals to help protect against the intrusion of dust and moisture.

In a statement the firm claims: ?By coupling this lens with the Pentax 645D camera body, the user is assured of a durable, reliable digital imaging system that performs superbly in demanding outdoor settings ? even in rain and mist, or locations prone to water splashes or spray.?