Minolta MC Lens Aperture Blades Opening Slowly After Being Stopped Down

Hi All,

 

I just bought a Minolta MC Rokkor-PF 55mm f/1.7 lens (MC without stop down lever, 52mm filter thread) in very good cosmetic condition. The glasses are all clean. However, when I put this lens on my XD film body, I noticed that the aperture blades closing down instantaneously but taking 3-4 seconds to open up again. I do not see any oil on the blades.

 

I took the lens off the XD body, and manually opened and closed the aperture by rotating the aperture ring. The blades moved in and out instantaneously as well. Very snappy. Then, I closed down the aperture and manually moved the pin in the back to open up the blades, as what a Minolta film body would have done. The same behavior happened. I saw that a shorter pin in the lens mechanism in the back was slow to follow the longer pin that I nudged with my finger. So the blades opened up just as slowly.

 

Does anybody know if this is normal behavior with Minolta MC lenses? Or is there something wrong?

 

I put this lens on a Minolta X-570 body, and the same behavior happened. Thank you in advance!

Not normal behavior. Sluggish aperture can be caused by sticking in the various linkages within the lens, as well as by oil on the blades themselves.