Yes, the aperture mechanism is dirty/gummed up: the lens needs a CLA (clean, lubricate, adjust) service. The auto-aperture actuating lever should snap back instantly, somewhere around 10-20 milliseconds max. Half a second is almost literally forever in terms of these mechanisms.
G > On Jan 29, 2023, at 2:02 AM, Ciprian Craciun <[email protected]> > wrote: > > ...So, I have the following problem with a Pentax D-FA 100mm macro lens: > the aperture system on the lens is sluggish to respond and thus all > images are overexposed, especially on high f-stop numbers (i.e. 5.6, > 8, 11 and onward). > > ... > (A) First of all empirically, I've detached the lens and removed the > caps, then looked through it which by default is fully closed (f/20+). > Then I've manually pushed the aperture lever wide open and suddenly > let it go (just like the camera I presume does). The aperture blades > don't snap back to the fully closed position, but slowly crawl to that > position. Here "slowly crawl" is compared with how other lenses react > to a similar experiment; but in real time it takes perhaps half a > second or a bit less. > ... -- %(real_name)s Pentax-Discuss Mail List To unsubscribe send an email to [email protected] to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
