On Tue, May 15, 2012 at 09:56:10PM -0700, Larry Colen wrote: > > On May 15, 2012, at 9:43 PM, John Francis wrote: > > > > > I've run into a problem trying to use my (Vivitar) auto extension > > tubes with my K-5. > > > > Scenarion: Camera set to "M", lens (A 50/f1.4) set to f/22. > > > > With the lens directly mounted to the camera, everything works as > > expected: DOF preview stops the lens down to f/22, and the exposure > > check showshow far I am off from correct exposure. Taking theshoot > > results in an image correctly exposed at f/22. > > > > If I put one of the extension tubes in place, though, the lens > > stays wide open at all times, and the image is captured at f/1.4 > > [no other changes to the settings on either lthe lens or the body] > > > > This is not what I expect (or want). Any clue as to what is wrong? > > Maybe the extension tube isn't moving the stop down lever.
If the extension tube wasn't moving the stop-down lever, the lens would remain stopped down; it only opens up when it is mounted on the body. > 1) Does it work with other lenses? Haven't tried. > 2) When you take a lens off, then use the depth of field preview, can you > see things moving on the camera body to trigger the stop down lever? No. But something must move when I mount the lens (without the extension tubes). > 3) When you put the extension tube on, and use the DoF preview, can you see > things moving at the exposed end of the extension tube? No > 4) If you put the lens on the extension tube, and poke and prod with your > fingers, can you get the lens to stop down? Yes -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
