[rollei_list] Re: Contrast and Resolution
- From: "Eric Goldstein" <egoldste@xxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Fri, 9 Nov 2007 09:47:25 -0500
Neil -
As you are familiar with shooting a test chart, a thought experiment
may prove helpful...
Imagine examining the negative of a test lens where the test chart's
hard contrast of black and white lines is reduced to gray and white
lines by the lens. Still, each line (to the limit of lens and film) is
recorded, but the contrast is reduced. The contrast can be
significantly reduced (50%, 75%, more) and still the eye can record
the detail...
Further, think about the effects of apodization on the lens (detailed
in a previous post)... Are the edges of the smallest of the visible
test chart lines darker along the edges or in the center? Further
thought along these lines in this experiment might lead to an insight
of why light energy drawn in the center of the points would lead to a
greater number of smaller lines being recognizable than light energy
drawn on the edges of the points...
Eric Goldstein
--
On 11/9/07, Neil Gould <neil@xxxxxxxxxxx> wrote: (snipped)
>
> > From: "Eric Goldstein" <egoldste@xxxxxxxxx>
> >
> > Neil -
> >
> > This is the flaw in your thinking... what leads you to believe that a
> > lens with lower contrast will necessarily have lower resolution?
> >
> I'm trying to understand how one can resolve details without the
> surrounding contrast.
>
> > Also, have you ever photographed a lens test chart and examined the
> > resulting negative under a microscope? In the times Ed was discussing,
> > this was one of the common procedures for testing resolution sans
> > contrast.
> >
> I understand this procedure, but it doesn't clarify what is meant by
> resolution sans contrast.
---
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