Olympus-OM
[Top] [All Lists]

[OM] Re: chips on rear lens (e)lement of Z 21/3.5

Subject: [OM] Re: chips on rear lens (e)lement of Z 21/3.5
From: "Brian Swale" <bj@xxxxxxxxxxxxxxx>
Date: Mon, 13 Nov 2006 11:14:27 +1300
Hello all,

I think I have figured out why dark images of the aperture show on my recent 
prints. It goes like this.

The whole image comes from quite bright conditions. Even stopped down to 
f/8 at 100 asa the camera was complaining that 1/2000 was not fast enough -
 depending on exactly where I had it pointed.

Direct sunlight was probably entering the lens and going right through to 
strike the interior side of the barrel behind the aperture blades and creating 
a 
bright patch (secondary light source). The front side of a rear lens element 
also was illuminated enough to create a tertiary light source from another 
angle.

The rear side of the aperture blades - now in stopped-down position - were 
illuminated (even matt black will radiate something if not extremely black) 
and then radiated this light towards the film; this light was focussed by the 
rear lens elements. 

Thus all of the film image received an extra dose of white light; all that is,  
except the parts (two in these cases) where the empty space of the aperture 
did NOT reflect / radiate light to the film.  These two hexagonal spaces (two 
sources involved) are therefore darker.

Therefore no dead pixels involved. Poof (*@*) goes another theory.

IMO

Brian

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

<Prev in Thread] Current Thread [Next in Thread>
  • [OM] Re: chips on rear lens (e)lement of Z 21/3.5, Brian Swale <=
Sponsored by Tako
Impressum | Datenschutz