Pentax K10D Operating Manual page 211

Lens names and mount names
FA prime lenses (non-zoom lenses) and DA, D FA, FA J and F lenses use
the K mount. Of the FA zoom lenses, power zoom enabled lenses use
AF
the K mount. Lenses without power zoom use the K
AF2
lens manual for details.
Lenses and accessories that cannot be used with this camera
When aperture ring is set at other than s (Auto) or a lens without a s
(Auto) position or accessories such as an auto extension tube or auto
bellows are used, camera does not operate unless [Using aperture ring] is
set to [Permitted] in the [A Custom Setting] menu (p.35). Refer to "Notes
on [Using Aperture Ring]" (p.210) for restriction that apply when [Using
aperture ring] is set to [Permitted] in the [A Custom Setting] menu.
All camera exposure modes are available when using DA/FA J or lenses
with Aperture s (Auto) position set to the s position.
Lens and Built-in Flash
The built-in flash cannot be regulated and fully fires when pre A lenses or
soft focus lenses are used.
Note that the built-in flash cannot be used as an Auto Flash.
mount. See the
AF
209
5