Archived posting to the Leica Users Group, 2003/04/26

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Subject: Re: [Leica] Digital Aesthetic
From: Johnny Deadman <lists@johnbrownlow.com>
Date: Sat, 26 Apr 2003 11:59:18 -0400

On Saturday, April 26, 2003, at 11:38  AM, bdcolen wrote:

> They probably will - but they may well come up with a firmware, or
> software fix, and neither of those will require a new camera purchase.


I don't think so.

The chromatic aberration (CA) 'problem' is chiefly a lens problem, and 
(just possibly) a sensor issue, or more precisely an interaction 
between lens and sensor design. It is vastly unlikely to be solved in 
software or firmware. The only way to correct CA in software is to 
apply differential radial transforms according to the wavelength of 
light. There are ways of doing this but they are complicated and 
non-optimal. For example, one can apply different radial transforms to 
the R, G, and B layers (panotools will do this) but there is no way in 
hell they are going to do that in the 1Ds firmware and in any case 
theoretically it is the wrong way to do it and will cause softness in 
the edges.

Moreover you would need to parametrize the transform differently 
according to which lens was being used and what focal length it was 
zoomed to.

In any case, I believe the CA problem is chiefly a lens issue. Wide 
zooms are notoriously hard to correct for CA, and most 35mm shooters 
would not have seen the CA because most 35mm film simply isn't good 
enough to see the fringing. The 1Ds sensor, as anyone who's used one 
knows, is massively unforgiving of lenses. It will take all the lens 
you can throw at it and then some. Right now with the 1Ds we have 
reached the point where the lenses not the sensor are the limiting 
factor.
>
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John Brownlow

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