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Meta and help us grow.  Take the 2-minute tour ×  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 tube