While asking for extension tubes for a Pentax DSLR, Pentax replied:
As requested, please find the following extension tubes available. Product 30535, auto extension tube set B Product 30551, life-size auto extension tube B 50mm w/case Product 30556, life-size auto extension tube B 100mm w/case
After searching for these products online I found different information regarding them. One forum post somewhere said the only auto part is that the meter at the widest aperture and stop down to the smallest. Is this true?
My intuition is that extension tubes stop down to whatever aperture is set in the camera. Perhaps they would be able to autofocus too but I do not care about that :) Only that there is still control over aperture without a lens with an aperture ring.
Does anyone know how the automatic aperture and metering work with these tubes?