unfortunately it does not work that way. When in M mode the focal length used determines the fixed choice of two apertures eg. 5.5/17.3. choosing one of those needs you then to switch to shutter mode and step through the range until you see the +(over exp) or the -(under exp) symbol disappear from the little yellow triangle alongside the f number.Setting a shutter speed first will not work. If you zoom the lens in and out you will see the f stops change but in each case you will only have a choice of two. I really cannot see why Pentax bothered with this, it is something of nothing and is very misleading as you assume that you have a much better level of control.
having said that it does produce excellent photographs.
Derek

Thank you all for the helpful responses, particularly from JohnX. As said it does not have shutter or aperture priority modes. In fact what it does have is a poor attempt at manual control and is utterly useless. I am very disappointed with Pentax. If they are going to put buttons on a camera then at least make them useful. By the time you've mucked about with these the shot is long gone. It just pays lip service to manual operation. On another point; the little cord provided to secure the lens cap to the strap when threaded to the cap prevents it from seating properly in the lens.

Hi,
I have been persuaded to buy the X5, impressed by talk of being able to manually control exposure. My understanding was that by selecting the M setting and choosing a shutter speed the camera would automatically select the corresponding aperture for the given light condition. The camera has the ability to switch between shutter and aperture setting but the aperture remains at either f9.7 or f3.1 when stepping through the shutter speeds. Various general internet topics indicate that when choosing M setting the camera syncs shutter speed with changes of aperture or vice versa. The manual offers little information on the topic. Am I missing the point here??