Originally posted by Ash I've heard others' reports stating that the aperture lever (or whatever it's called on the inside of the mount, not the aperture ring) gets stuck once in a while, leading to inaccurate exposures, though all those I heard got stuck wide open rather than completely stopped down.
Check it out for yourself, have a *very* gentle play (if you know what you're doing) with the lever that controls the aperture to see if it's free and not caught anywhere. Sad to hear this thing happening more than occasionally on such a great lens.
most of the people are reporting aperture stuck at wide open (that was my case too).
In any case lookingthrough the lens at f22 even without TC would be veeeeeeeeeeeeeeeeeeeeery dark and very noticable. With 2xTC we'd be talking what, f45 as result? You really wouldn't see much through.
Try the lens without the TC, if it works OK on it'sown, then there's problem in lens-TC-body comunication. Checke the levers on the lens and the TC.
BR
Peter