December 25, 2009
K 100D pentax camera – personal notes
The Sigma 70-300 lens often ‘freezes up’ on K100D without warning. That is because some mishanding has loosened the aperture ring. The camera simply won’t recognise the lens when that happens.
Go to page 139 of the manual (softcopy available here) and look at the last paragraph on the page. The aperture ring is the first ring from the point where the lens is connected to the camera. The ring must not move (if it does, that means its setting is no longer working).
If the ring is moving, press the little black knob and move it so that the little white mark (peer below the ‘PENTAX’ flash system that over-hands this mark) is facing Number 22. At that point release the black knob. The aperture ring should become firm and stop moving. Now the camera is ready to work again.
Some guidance also available here: http://www.grimes.nildram.co.uk/book/chapter_six/chapter_six.htm (Using Your Pentax K100D by Richard Grimes).