Originally posted by Groucho I played with Dust Alert for the first time tonight and noticed that it only works when the camera is in autofocus mode.
It is disabled (grayed-out in the menu screen) when the camera is set to Manual Focus mode.
So, if you're using a manual focus lens, just switch to AF and give it a try. I haven't attempted it yet myself, but I suspect that it'll work fine.
Only partially true . . . there is no functionality with lenses other than of the Autofocus variety. True, with AF lenses, the focus switch needs to be in the AF-S or AF-C position to use the function (not grayed out). With manual focus A or K lenses it is not a selectable option. If you add an AF teleconverter to a manual focus lens, it will work. Given this function is something you would typically access seldom (and typically not while shooting), it shouldn't be a problem to mount an AF lens at a later time.
I have asked Pentax US to verify this (lack) function and they concur. I have asked also they submit it as a 'bug' for correction in future firmware (or at least a manual correction.)