Auto ISO not working on Pentax K100d

[The View]

I set my Pentax K100D to Auto ISO 200-800.

And, additionally, mostly in aperture priority mode.

Now, when the exposure time gets long, let's say, under 1/60th, I expect Auto ISO to kick in and increase the ISO to 400 or more.

But when it gets darker, the shutter time gets longer and longer, and I finally have to change the ISO by hand to a higher value.

Is it me, or is it the camera? Does Auto ISO only work under certain circumstances?

Thanks.

[Bobtrips]

I set my Pentax K100D to Auto ISO 200-800.

And, additionally, mostly in aperture priority mode.

Now, when the exposure time gets long, let's say, under 1/60th, I expect Auto ISO to kick in and increase the ISO to 400 or more.

But when it gets darker, the shutter time gets longer and longer, and I finally have to change the ISO by hand to a higher value.

Is it me, or is it the camera? Does Auto ISO only work under certain circumstances?

Thanks.
[{POST_SNAPBACK}][/a]

I haven't had that problem with my K100D.  You might try the [a href=\"http://www.pentaxforums.com/forums/]Pentax Forums[/url] where the question will be seen by more Pentax owners.

[The View]

Thanks for the tip.