05-12-2014 10:53 AM - edited 05-12-2014 04:02 PM
Greetings. While we're not able to confirm compatiblity or limitations of after-market lenses with PENTAX DSLRs; if your lens features an auto-aperture setting (ie: "A" setting on the aperture ring), you way wish to select that setting on the lens. If your lens does not feature an "A" or auto setting on the aperture ring, you will have to access the Custom Setting menu #22 "USING APERTURE RING" and select "Enable". Thanks.