Hello,

There is no lock screw.
You just have to find a rubber cork who have the same size as the
front piece.
I'v found one from a big glass from my chemist department.
If you look here
http://www.micro-tools.com/store/item_detail.aspx?ItemCode=JHT-C
you will see 3 rubber cock on the tool box.

Push the cock on the front piece and unscrew...

After you have 3 screw to remove and you have all the front lens out.

Unscrew the 2 small silver screw on the diaphragme and remove the
diaphragme.

I've cleaned the 7 blade one by one and mine 50 F1.8 work perfectly
now.

I've found on the net the repair manual but it's on my office
computer.

If you need help I can made some picture of mine also.

Bernard

--- In NikonRepair@yahoogroups.com, louis <louisx@...> wrote:
>
> Robert
>
>
>
> I think the front piece you want to remove unscrews. But look for
a lock
> screw anyhow.
>
> You can remove it by using a piece of rubber like a jar cap opener
to create
> a grip.
>
>
>
> You may not have to remove it if you can clean the blades.
>
> The way I do it is to get a Q tip and use Ronsonol aka naptha.
>
> It does not mess up plastics.
>
> Dampen the Qtip and apply gently in the direction of the blade
overlap so
> you don't bend the blades. Use a dry Qtip to remove excess. Let it
dry and
> apply/exercise a few times until you are satisfied with it. Then
clean the
> lens. The Ronsonol dissolves the oil so that it can be picked up
by the dry
> Qtip. If all works well it actually cleans both sides
>
>
>
> LOU
>
>
>
> _____
>
> From: NikonRepair@yahoogroups.com
[mailto:NikonRepair@yahoogroups.com] On
> Behalf Of Robert
> Sent: Thursday, May 15, 2008 4:33 PM
> To: NikonRepair@yahoogroups.com
> Subject: [NikonRepair] nikkor 50 f1.8 blades cleaning
>
>
>
> Hi,
> I took a lot of pictures during a wind+sand storm, and after the
photo
> session i noticed that a lot of sand entered inside my nikkor.
>
> I decided to unmount the lens and clean it. As expected the lens
was
> full of sand.
> After the cleaning i put some oil, but i let a drop fall inside the
> aperture blades..
>
> The blades are stuck, because of the viscosity of the oil. I
unmounted
> the rear group lens and started to clean the blades from the back :
>
> http://www.stockblo <http://www.stockblog.it/extra/bladesback.jpg>
> g.it/extra/bladesback.jpg
>
> You can spot some oil from this picture :
>
> http://www.stockblo <http://www.stockblog.it/extra/front.jpg>
> g.it/extra/front.jpg
>
> I need to access the blades from the front, but i don't know how
> unmount the front group of lens :
>
> http://www.stockblo <http://www.stockblog.it/extra/how.jpg>
> g.it/extra/how.jpg
>
> can please someone give me a hint?
>
> thanks
> Robert
>
>
>
>
>
> [Non-text portions of this message have been removed]
>