12-40 aperture blades supposed to close when turning off camera?

fadingphoenix

Mu-43 Regular
Joined
Dec 27, 2013
Messages
27
This is just an oddity I observed a while back when trying to look through my dismounted 12-40. Unlike other lenses I've owned which keep the aperture blades wide open the 12-40 seems to close them when the camera is turned off. I haven't seen anyone else comment on it, so maybe it's a more common occurrence among lenses than I realize. It's something I've been curious about though. Has anyone else noticed this? Is there a reason for it? Is my lens behaving oddly?
 

JeanLucX

Mu-43 Regular
Joined
Oct 3, 2013
Messages
60
Location
NYC
mine is closed. I notice a few lens of mine with f2.8 have closed aperture blades so maybe it is common among lenses with f2.8 aperture.
 

fadingphoenix

Mu-43 Regular
Joined
Dec 27, 2013
Messages
27
Interesting. I'm a recent convert from the old 4/3rds and I've never seen that behavior before.
 

Rudy

Mu-43 Top Veteran
Joined
Jan 24, 2013
Messages
529
Location
Oakland, CA
Makes it less likely that you would burn a hole into your sensor should the camera be laying around pointing at the sun.
Old Leica rangefinders with cloth focal plane shutters had a similar problem...
Rudy

This is just an oddity I observed a while back when trying to look through my dismounted 12-40. Unlike other lenses I've owned which keep the aperture blades wide open the 12-40 seems to close them when the camera is turned off. I haven't seen anyone else comment on it, so maybe it's a more common occurrence among lenses than I realize. It's something I've been curious about though. Has anyone else noticed this? Is there a reason for it? Is my lens behaving oddly?
 

zulfur666

Mu-43 Veteran
Joined
Jan 30, 2014
Messages
254
my 12-40 has a very tiny opening I assume it would be f22 but its not completely closed. I still see light through it. Where my 60mm 2/2.8 Macro is wide open.
 

dolbydunn

Mu-43 Regular
Joined
Dec 28, 2013
Messages
52
Location
Ohio
Makes it less likely that you would burn a hole into your sensor should the camera be laying around pointing at the sun.
Old Leica rangefinders with cloth focal plane shutters had a similar problem...
Rudy
As a former camera repairman I have seen the Leica C with the cloth shutter having small 1/16" holes burned thru the shutter curtains by the focused rays of the sun. I had forgotten about that until you mentioned it. Cool.
 

Latest posts

Links on this page may be to our affiliates. Sales through affiliate links may benefit this site.
Mu-43 is a fan site and not associated with Olympus, Panasonic, or other manufacturers mentioned on this site.
Forum post reactions by Twemoji: https://github.com/twitter/twemoji
Copyright © 2009-2019 Amin Forums, LLC
Top Bottom