I have an old Tamron 90mm f/2.5 Macro, manual focus (the second version, with knurled focus ring).
The lens came with an Adaptall-2 ring, with electric contacts (K/A).
When i bought the lens, the Adaptall ring was not properly mounted. I took it out, remounted the ring properly, and found that the diaphragm lever was not moving freely, causing exposure problems.
I slightly bent the lever, and since then the lens worked well (i had to re-do a bit of bending one more time, cause the lever got somewhat stiff, probably for lack of use).
I am on vacation now, with my new (second-hand) K-5 II, and my trusty K200D as second/spare body.
Before leaving i didn't test the Tamron with the K-5, it was working with other cameras, so why it should not work with a newer, and better camera? :-)
Unfortunately today i discovered that my assumption proved not true.
I just tried with both cameras, many times, after removing and re-mounting the ring countless times:
the lens works perfectly with the K200D, and does not work at all with the K-5 II !!
It is immediately evident, the image in the viewfinder is dark, cause the iris is closed (if set to A), or at the set aperture (if not set to A).
The iris should open completely, once the lens is mounted, and should close to the working aperture just an instant before the picture is taken. That's what happens with the K200D.
I must say that there is something a little strange with this lens: if i remove it from the body, the diaphragm lever moves smoothly if pushed with a finger, but if i move the diaphragm ring away from "A", and close the iris step by step from f/2.5 to f/22, you can see the diaphragm blades closing... until it reaches midway between f/8 and f/11. Stopping down further, the blades close only after a slight "tapping" on the side of the lens body.
I can't check what happens if the ring is set to Auto ("A"), but i found that all the pictures i took with the K200D seem to be spot on, even dialing f/16 or f/22 using the thumb wheel.
I tried to describe the problem as well as i could, i hope it came clear.
It is obvious that there is a movement which is not totally free, in the adapter ring... but i can't understand why on earth the K200D takes perfect pictures (with the diaphragm ring set to A), while the new K-5 II can't even keep the iris open!
I tried with different exposition modes, i tried to operate the DoF preview, but to no avail.
It's weird that with the K200D everything is perfectly OK, i tried many times and all the pictures came perfectly exposed.
Any clue?
ciao
Paolo
Last edited by cyberjunkie; 03-30-2014 at 05:20 AM.