FA43 f/1.9 - Issue with using Aperture ring with a Pentax K-5

Greetings!In my ongoing pursuit of image sharpness, I just got the beautiful Pentax FA 43mm f/1.9 Limited lens. I thought I'd try using the lens' Aperture ring, so switched the lens out of "A" mode, and tried setting the aperture manually to, say, f/8. After doing this and looking at the Live View to move the Focus Selection Square over a certain area of the scene, I noticed it did not let me move it around in the subject area. This behavior disappeared after turning off the camera and switching back to "A" mode on the lens, powering up the K-5 and then setting the Aperture via the rear dial on the camera. Is this "normal" behavior for this lens on a K-5? Should one be able to use this FA lens in "Manual" mode with the Aperture ring? (This is my very first "FA" lens, and I did not change the default Custom Setting #27 (Using Aperture ring) Thanks, Steve

There is absolutely no advantage, and many disadvantages as you have found, to taking the aperture ring off the "A" setting.

If you want to use a particular aperture, set the mode dial to Av, set the aperture using the camera dials and the camera will set an appropriate shutter speed.

I think if you take the lens out of "A" mode, you have to set the camera to "use aperture ring". Again, I think, the default setting in the camera is not to use the aperture ring.

Thank you, John and Barrie! I shall indeed keep the lens set to "A" mode. I think it's a superb optic, and will continue testing it as time permits, but so far, am extremely impressed with its sharpness and detail rendition on the K-5. As you can see from my main site, www.totalqualityphoto.com, I am very much into the rendition of detail in my images. Have a fantastic year! ~Steve