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[OM] Re: can your digital do this?

Subject: [OM] Re: can your digital do this?
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxx>
Date: Wed, 04 Feb 2004 10:25:36 -0500
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


C.H.Ling wrote:

> It also surprise me when I saw this shot, in the pass I mainly use it for
> flowers and sometimes portrait, never notice about the chroma problem.
> Similar problem also found on the Zuiko 180/2.8, although these two lenses
> are not technically perfect but they are my favorite lenses, always give me
> beautiful results. And yes, we usually see chroma on the edges of wide
> angles but the highly corrected Zuikos 18/3.5 may be an exception. Besides
> heavier light falloff it is very sharp edge to edge, it beat the Tamron 17
> hands down in corner resolution.
> 
> 
> C.H.Ling
> 
> ----- Original Message ----- 
> From: "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxx>
> 
> 
>>I find it very interesting that the chroma is in the center of the field
>>on a short telephoto (and one of the best) when all we've ever been told
>>to expect is that the chroma will be found on wide angles at the edge of
>>the field.
>>
>>What do you think is going on here?
>>
>>Chuck Norcutt
>>
>>C.H.Ling wrote:
>>
>>
>>>Bob, glad to hear you like them. I can't put the 24 shift on the 10D as
> 
> I
> 
>>>sold it last April to finance the 10D. Can't resist a US$1900 offer for
> 
> the
> 
>>>shift, it almost cover a 10D, vertical grip and a used 28-135 IS.
>>>
>>>Color fringing? do you mean on the 24 shift? I didn't see visible chroma
> 
> on
> 
>>>the 24 shift and I believe it will not found on the 10D. Same for the
> 
> 18/3.5
> 
>>>but I do see some chroma on the 90/2, below is a shot at around F4 or
> 
> 5.6
> 
>>>which shown quite a lots of chroma on the water reflections.
>>>
>>>http://www.accura.com.hk/CRW_4195.jpg  (~1MB)
>>>
>>>Below is a shot from 18/3.5 at f5.6 1/30s, ISO400. It was not very sharp
> 
> but
> 
>>>can be used for checking the chroma (the strong spotlight areas).
>>>
>>>http://www.accura.com.hk/IMG_1277.jpg  (~850K)
>>>
>>>C.H.Ling
>>
>>
>>
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