Cleaning oily aperture blades on a AF lens

xkaes

Subscriber
Joined
Mar 25, 2006
Messages
4,791
Location
Colorado
Format
Multi Format
I just got a Minolta Maxxum 50mm f1.7 lens. I haven't used it yet because it has a problem. It looks great, and I got it for free -- so I can't complain -- but the aperture blades are stuck open due to oil.

I've cleaned oily blades on plenty of manual-focus lenses -- NON-zooms -- but I'm wondering if the nature of an AF lens makes this more difficult.

Do you think cleaning these blades will be:

A: E.Z.P.Z
B: P.I.T.A.
C: D.O.A
or D: All of the above
 

Andreas Thaler

Subscriber
Joined
Nov 19, 2017
Messages
4,863
Location
Vienna/Austria
Format
35mm

I would clean the aperture blades like I would do with other lenses: with lighter fluid or isopropyl alcohol.

See

Nikkor AF 20/2.8 D: Stuck aperture blades, lens clouding

I could purchase this lens cheaply. The aperture blades are likely oily and there is some clouding around the rear lenses. I looked at what I can do for the nice 20 👍 Externally in mint condition. The clouding in the rear optical component under focused LED light. ... and under...
www.photrio.com
 
OP
OP

xkaes

Subscriber
Joined
Mar 25, 2006
Messages
4,791
Location
Colorado
Format
Multi Format
A: E.Z.P.Z -- Easy as Pie
B: P.I.T.A. -- Pain in the ass
C: D.O.A -- Dead on Arrival
or D: All of the above -- A, as well as B, and including C
 
OP
OP

xkaes

Subscriber
Joined
Mar 25, 2006
Messages
4,791
Location
Colorado
Format
Multi Format

I wasn't asking about what to clean them with. I would, of course, use the same materials and procedures. I was wondering if it is more difficult to gain access to the aperture blades due to it's nature of being an AF lens.
 

Andreas Thaler

Subscriber
Joined
Nov 19, 2017
Messages
4,863
Location
Vienna/Austria
Format
35mm
xkaes said:
I wasn't asking about what to clean them with. I would, of course, use the same materials and procedures. I was wondering if it is more difficult to gain access to the aperture blades due to it's nature of being an AF lens.
Click to expand...

That depends on how the lens is constructed. There is no general statement about this.
 

Andreas Thaler

Subscriber
Joined
Nov 19, 2017
Messages
4,863
Location
Vienna/Austria
Format
35mm
I would start by loosening the two small screws on the inside and the black panel should come off. Then remove the contact block if necessary. If that doesn't help, I would unscrew the bayonet.
 

Andreas Thaler

Subscriber
Joined
Nov 19, 2017
Messages
4,863
Location
Vienna/Austria
Format
35mm
From the Minolta Service Manual:



It should work when you remove the panel (rear light shield ring).

It's best to try it out.
 
OP
OP

xkaes

Subscriber
Joined
Mar 25, 2006
Messages
4,791
Location
Colorado
Format
Multi Format
I made some progress. Getting at the oily blades was pretty easy. No need to remove the electrical contact plate -- it comes off by removing the rear cover. Then the rear lens group is held in place by three screws. BUT, when you remove the rear plate a TINY spring falls out. Lucky I saw it. It's right next to the "7" in the red box (above). The service manual just labels it as "spring", but my guess is that it is an electrical connection -- perhaps a "ground". It fits into a tiny socket on the inside of the rear plate.

As to the oil, I've never seen blades this oily. After four cleanings, it's still oily -- too oily. My guess is that the blades are somehow. mysteriously connected to the oil fields in Saudi Arabia.
 
Last edited:
OP
OP

xkaes

Subscriber
Joined
Mar 25, 2006
Messages
4,791
Location
Colorado
Format
Multi Format
After about a dozen tries, the aperture is working correctly. I still don't know what all that oil was doing in the lens. And I still have to figure out where that tiny spring is supposed to go. It's so small, I can only pick it up with tweezers. I hope I put it back in the right place.
 
You must log in or register to reply here.
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…