Digital BW, The Print

Ernst,
Are you a math scientist or what? Your volume of information always  
amazes me. Must be big brained.
:)Mark

On Feb 23, 2006, at 7:42 AM, Ernst Dinkla wrote:

> Ernst Dinkla wrote:
>
> > I think a true optical resolution
> > above 3000 PPI for 4x5 and smaller isn't impossible.
>
> Doing the maths again and starting from the 2000 PPI true
> optical resolution estimation of Rafe's 4990.
>
> A straight 6400/4800 x 2000 PPI (true optical resolution as
> estimated by Rafe for his 4990) would give 2666 PPI true
> optical resolution. But the max scan area for high resolution
> is 150 x 247 mm ( Effective pixels data) which probably means
> the windows of the twin 4x5 holder are not in the length. The
> 216 x 297 mm area for the lower resolution used means that if
> there's 2000 PPI true optical resolution on the total width of
> the bed ( Rafe's estimation for his 4990) the high resolution
> should be about 2880 PPI true optical resolution (216/150 x
> 2000). The smaller angle of the lens and the less DOF needed
> with the dual lens system may get it over the 3000 PPI mark.
> If the twin 4x5 holder had the windows lengthwise then the
> stroke of the lens for higher resolution doesn't have to be
> wider than 95 mm (4 inch minus the unexposed borders). That
> could have brought the resolution near 4500 PPI. All based on
> one axis calculation. There are probably other (optical)
> limitations though that make this wishful thinking.
>
> Ernst
>
>
>                     --
>            Ernst Dinkla
>
>
> www.pigment-print.com
> (         unvollendet         )
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