Chromatic aberration programs fix lateral chromatic aberration, which is the
image magnification being different for different colors. They just shrink
or expand the different colors to bring them back into registration. LCA
increases with distance from the axis and is not improved by stopping down.
Your picture looks, to me, like longitudinal chromatic aberration which is
due to different colors having different focal lengths. This can be present
at the center and improves with stopping down.
Paul Farrar
----- Original Message -----
From: "C.H.Ling" <chling@xxxxxxxxxxxxx>
To: <olympus@xxxxxxxxxx>
Sent: Wednesday, February 04, 2004 9:36 AM
Subject: [OM] Re: can your digital do this?
>
> Chroma is not necessary happen on the edges, here is the test for Zuiko
> 180/2.8 with film not digital.
>
> http://www.accura.com.hk/OM/180TEST.htm
>
> C.H.Ling
>
> ----- Original Message -----
> From: "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxx>
> To: <olympus@xxxxxxxxxx>
> Sent: Wednesday, February 04, 2004 11:25 PM
> Subject: [OM] Re: can your digital do this?
>
>
> > I tried repairing your image in PW Pro using the chromatic abberation
> > tool. It has no effect except to worsen the image toward the edges of
> > the field since it assumes that chroma is zero at the center (as it
> > should be) and gets worse the further you move off axis (as do almost
> > all optical abberations)
> >
> > I then tried to repair it using the scanner registration tool. The
> > scanner registration tool is for fixing scanner related problems where
> > the registration of the red green and blue channels are slightly off
> > from each other. However, that had no effect either other than to
> > worsen the image. I expected that since I think a registration error
> > would cross the entire image but I decide to try it anyhow.
> >
> > I still don't understand what's going on here.
> >
> > Chuck Norcutt
>
>
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