p.1 #1 · Aperture sometimes stops down randomly on 50/1.4 GM
My 50/1.4 GM lens is about 2 years old. It has started changing its aperture seemingly randomly, regardless of which camera it is mounted on. For example, with the aperture ring set at f/1.4, pressing the shutter button will sometimes cause the lens to stop down to anywhere from f/1.6 to f/5.6 for no apparent reason. If the camera is in Aperture priority mode, and set to auto-ISO, this automatic stopping down will make the camera raise its ISO and/or lower its shutter speed to compensate for the stopping down. If the camera is in Manual mode, with a fixed ISO, this automatic stopping down will make the camera underexpose. However, sometimes the stopping down doesn't happen and the lens works normally.
I looked for firmware updates for this lens, but found none. I tried cleaning the contacts and resetting the camera's settings, but that didn't help. Is this aperture problem fixable? What might be causing it? Thanks in advance for any ideas!
p.1 #2 · Aperture sometimes stops down randomly on 50/1.4 GM
Does anyone have a recommendation for a repair service that can replace a Sony GM lens aperture ring? It looks like Precision Camera charges $561.00 (with shipping) for any repair on a 50/1.4 GM lens. Is that the best option?