Originally posted by Shaneuk if all 3 lens had the same issues I'd assume it was the camera but as pentax kit lens is still perfect I'm baffled.
If the camera thinks the attached lens is a manual lens it is because there is a problem with the communication contacts. The problem is finding out what that problem is.
- cleaning the contacts is the first thing to do, on both lenses and camera
- since the Pentax works and the Sigmas don't that implies the problem is with the Sigma lenses
- Non-Pentax lenses might be ever so slightly different than a Pentax lens, not enough to matter usually but can be an issue if something else is loose
- Check the mounts on both the Sigma lenses and on the camera and make sure all of the screws are tight and all of the contacts are present and look correct
- If you have access to another Pentax camera (perhaps a local shop will test for you) try the Sigma lenses there and see if they work