Originally posted by Votesh the buyer noticed that when the converter was on the lens the aperture would not open all the way to 2.5.
What does "the aperture would not open all the way to 2.5" means exactly?
If I'm not mistaken, the lens has PK mount so "the aperture would not open all the way to 2.5" can't mean the camera body can not set the lens's aperture to 2.5.
With the exception of the Pentax 1.7X AFA, I've never seen a TC (including the ones with PKA mount) that modifies the aperture setting signal.
I don't have the particular lens and converter, but if "the aperture would not open all the way to 2.5" means the aperture ring on the lens can not be set at 2.5, there is some problem.
There are no electrical contacts between the camera body and the lens. The camera doesn't know anything about the lens and the converter. The lens doesn't know if the converter is there. Why is there the problem only when the converter is attached? I'm confused.
I know I'm no help. But I'm just curious.
Edit to add: At close range, the
effective aperture is not the same as the setting of the aperture ring. The aperture markings are calculated at infinity. In general, at 1:2, the lens is 1 stop slower than the setting; at 1:1, 2 stops slower.
Last edited by SOldBear; 08-19-2009 at 06:57 PM.