roetronxoay
30-Apr-2020, 12:11
Hi all,
I recently bought a Pentac 8" 2.9 for a good price but just realized it has stuck apertures. It can neither open widest or close down to the smallest f-stop, it only moves about in-between distance. 1 of the blades seems to have been out of position when I unscrewed the rear element check (got some creaking sounds when I did this). So I tried to access it from the front but the front element won't unscrew and feels very tight. Also, when I remove the aperture ring, I found out that the reason it couldn't close down smaller was because the aperture connecting "hole" had already reached the end of its travelling, meaning somehow the aperture mechanism had been put in the wrong position inside? and it can't open more because the blades got stuck? Previous owner had hot-glued a home-made lens board on the mounting thread (!!!), so could that be one of the reasons? Appreciate any inputs. And sorry for my lack of my technical terms knowledge.
Pics are of current position of the blades with aperture at the end of its travel.
203228
203229
Thien
I recently bought a Pentac 8" 2.9 for a good price but just realized it has stuck apertures. It can neither open widest or close down to the smallest f-stop, it only moves about in-between distance. 1 of the blades seems to have been out of position when I unscrewed the rear element check (got some creaking sounds when I did this). So I tried to access it from the front but the front element won't unscrew and feels very tight. Also, when I remove the aperture ring, I found out that the reason it couldn't close down smaller was because the aperture connecting "hole" had already reached the end of its travelling, meaning somehow the aperture mechanism had been put in the wrong position inside? and it can't open more because the blades got stuck? Previous owner had hot-glued a home-made lens board on the mounting thread (!!!), so could that be one of the reasons? Appreciate any inputs. And sorry for my lack of my technical terms knowledge.
Pics are of current position of the blades with aperture at the end of its travel.
203228
203229
Thien