Thanks, Peter. That was the theory I arrived at overnight. I was going to conduct experiments this morning to test the hypothesis, but you've rendered that unnecessary. I'll try the alfoil trick.
On Wed, May 16, 2012 at 04:22:32PM +0930, Peter Loveday wrote: > Just tried this, and I'm seeing the same thing too, with an A28/2.8 > > I'm guessing the camera refuses to stop down at all if it thinks > there is no lens present. The vivitar extension tubes are black on > the mount (well, mine are anyway) and I'm guessing non-conductive? > > The alfoil trick on the contacts does seem to make it work as > intended. I'm now tempted to sand the paint off that part of the > mount on my tubes. > > - Peter > > > -----Original Message----- From: John Francis > Sent: Wednesday, May 16, 2012 2:13 PM > To: [email protected] > Subject: Problems with K-5 and extension tubes > > > 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? > > Fortunately I have a work-around; using the Fotodiox K-mount-to-m43 > adapter (and the same lens & extension tubes) on the Olympus E-PL1. > > Here's what I was trying to photograph: > > http://www.jfwaf.com/temp/pfsmini1.jpg > > That's a small metal figure a friend of ours painted for my wife to > use when we participate in tabletop role-playing games (Pathfinder). > For a size reference, the large knurled circular plinth at the very > bottom of the shot is a metal K-mount body cap. > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above > and follow the directions. > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.2176 / Virus Database: 2425/5001 - Release Date: > 05/15/12 > > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
