Pentax has unveiled new firmware updates for all of its flagship cameras - the K-5, K-r and the recently-released 645D medium format model.

While the update only brings support for SDXC memory cards to the 645D, K-5 and K-r users will benefit from an improved functional sequence of Contrast AF, as well as "improved total speed until focus is done," says Pentax.

The update also offers the possibility to select all ISO settings in Bulb mode, from ISO 80 to ISO 51,200 with the K-5, and from ISO 100 to ISO 25,600 with the K-r. Previously, the maximum value was 1600, says Pentax.

The new firmwares can be downloaded via the Pentax website.