Aperture cleaning help on 20mm AF F/2.8


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Pinjo

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Dec 31, 2009
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#1
Hi there!

Just new to this forum and i was wondering is someone could help repairing this lens mentioned (Nikon AF 20mm f/2.8) The aperture blades are sticking together and i want to open the lens to clean them. I am already able to reach the aperture blades from behind but in some way I need to remove the front object to remove the aperture. I was able to remove the plastic front ring but now I am unable to remove the inner mechanism. Does anybody know how to continue this dismantling?

Regards,
Pinjo
 

Octarine

Moderator
Staff member
Jan 3, 2008
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Pasir Ris
#2
Contact brother 'fatigue'. Otherwise the Consumer Corner has the data of The Camera Workshop and other shops that might be of any help. Finally, since it' a Nikon lens, Nikon Service Center would be an option as well.
 

Pinjo

New Member
Dec 31, 2009
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The Netherlands
#5
I have taken 2 pictures. As you can see i can see the aperture from the back (pretty greasy as you can see) but i am not able to remove the inside element to remove the two screws from the other side.
The plastic cover of the front is removed but the focusring is still stuck there. I don't know how to continue right now..


Picture from the back, aperture visible

The plastic cover of the front is removed but the focusring is still stuck there. I don't know how to continue right now..

Front picture
 

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fatigue

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Sep 26, 2005
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#6
You can't remove the blades from the rear part.
Although, you can do a simple cleaning by wiping the blades with degreaser.
It may or may not work, depending on how much grease leaked into the blades.

To overhaul the blades, you must access from the front.
But you need a special tool to remove the front optics.
You can try using a thin sheet of rubber for grip but make sure you put marking on the original location of the retaining rings

Caution:
Make sure you remember the arrangement/orientation of the rear optics.
Optics should also sit exactly on the spacers.
Any gap may result in misalignment.

Looks like you removed some screws which are not supposed to be removed.
This will affect the focusing. You need to adjust the focusing to infinity.

After putting back the lens in one piece, check the sharpness from edge to edge.
This is to ensure you returned the rear lens group properly

Good Luck
 

horizon_grazer

Senior Member
Feb 6, 2006
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#8
Can contact Nikon Service Centre for a price quote too..
 

Pinjo

New Member
Dec 31, 2009
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The Netherlands
#9
I am from the Netherlands so dropping by is not so easy for me :confused:
But for my information.. I should remove the front optics by turning the metal ring in front with that special tool?
Would that be holding tight the outer housing part and turn the metal ring? Clockwise or counter-clockwise?

@horizon_grazer
I could contact Nikon but I'm afraid the costs will be very high, especially when they need to align it again..
 

fatigue

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Sep 26, 2005
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#11
Managed to find some of my files

You need something like this


To remove the front cover


Then a special lens spanner to remove this lens group:
The spanner needs to grip on the 2 small canals indicated by yellow arrows
 

fatigue

Senior Member
Sep 26, 2005
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#12
Once you reach here, you need another lens spanner to grip on the 2 holes indicated by yellow arrows to remove one more lens to reach the blades

Note: Don't loosen the screws encircled in red
 

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