Olympus-OM
[Top] [All Lists]

[OM] Re: 28mm f/2.8 repair advice

Subject: [OM] Re: 28mm f/2.8 repair advice
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Thu, 30 Nov 2006 08:52:23 -0500
Thanks, John.  I can see the L shape in the parts diagram but don't 
recognize anything that I would have thought would interfere with 
pulling the ring straight up.  But I'll certainly follow your 
instructions.  I'm intrigued now to see what's actually holding it in 
place and, of course, to see what's preventing the full range of motion. 
I'm suspicious that the pin was simply misplaced when the lens was last 
assembled.  Perhaps it's on the wrong side of whatever mechanism it's 
supposed to mate with.  I'll soon see.

Thanks,
Chuck Norcutt

John Hermanson wrote:
> The pin on the 28 2.8 is L shaped and connects to the diaphragm control 
> cam through a slot in the main tube.  To remove the ring, you'll have to 
> take out the 2 screws holding the pin in.  Unscrewing the front lens 
> assembly, which would expose the diaphragm mechanism, should reveal what 
> the problem is.
> 
> ___________________________________
> John Hermanson
> Camtech Photo Services, Inc.
> 21 South Lane, Huntington NY 11743
> 631-424-2121 | Olympus OM Service since 1977
> http://www.zuiko.com  |  omtech1 AT verizon.net
> 
> 
> Chuck Norcutt wrote:
> 
>>Hey, here's a real, live, nitty-gritty, on-topic OM post!
>>
>>I have a 28mm 2.8 which will not open (using the diaphragm ring) to more 
>>than f/5.6.  The diaphragm blades open fully when the DOF preview button 
>>is not depressed but the diaphragm ring can't be rotated to either f/4 
>>or f/2.8.  It hits a hard stop at f/5.6.
>>
>>I assumed that there must be a problem with the detent ball but was 
>>surprised when I removed the filter/detent ring and found that the 
>>detent mechanism is fine and there is no appreciable wear on the ring.
>>
>>I tried rotating the diaphragm ring again without the detent ring and 
>>ball installed and it still hits a hard stop at f/5.6.  Then I tried to 
>>lift off the diaphragm ring and was surprised to discover that I 
>>couldn't.  I can lift the side opposite what I'll call the diaphragm 
>>coupling pin (CE157300 on the parts diagram) but that pin acts like it 
>>has a hook on the end.  The pin side lifts no more than 1/2mm and stops 
>>cold just as though what I think should be a flat bladed pin has a hook 
>>on the end and is catching on something.
>>
>>Any suggestions?  If I remove the lens mount will I be able to see the 
>>inside of the barrel and figure out what the obstruction is?  I guess I 
>>could also remove the two screws attaching the diaphragm ring to the 
>>coupling pin but I hate to disassemble what I don't have to.
>>
>>Thanks,
>>Chuck Norcutt
>>
>>
>>==============================================
>>List usage info:     http://www.zuikoholic.com
>>List nannies:        olympusadmin@xxxxxxxxxx
>>==============================================
>>
>>
> 
> 
> 
> ==============================================
> List usage info:     http://www.zuikoholic.com
> List nannies:        olympusadmin@xxxxxxxxxx
> ==============================================
> 
> 


==============================================
List usage info:     http://www.zuikoholic.com
List nannies:        olympusadmin@xxxxxxxxxx
==============================================

<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz