At 08:49 AM 6/15/2001 -0700, Paul Chefurka wrote:
>One of the things that has always struck me about my 4000 ppi scanned
>images is how much sharper the dust is than any image detail on the film -
>even films like Provia 100F. This implies to me that the film itself is
>the limiting factor for "image sharpness". While we might all like to see
>8000 ppi scanners for a number of reasons, we won't actually resolve much
>more image content that the current 4000 ppi models are providing.
>
>After all, 4000 ppi gives a resolution of 75 lp/mm or so, and it takes
>pretty remarkable technique to actually get that kind of resolution onto
>film. Or is my crude first-approximation assessment incorrect, and we
>actually can't resolve detail in the scan at more than half that - say 40
>lp/mm with reasonable contrast? Even that level is still sufficient for
>prints that appear "sharp" at normal viewing distances.
>
>Whatever the final outcome may be (once we've worked through the morass of
>differences between film and digital image reproduction technology and
>information theory) I'm still left with the feeling that current scanner
>resolution is getting off the film most of what's actually there. An
>order-of-magnitude improvement is probably not available in this system.
Quoting from the July 2001 Popular Photography film scanner review (sidebar
on p. 58):
"Even the best 4000 ppi scanners we've tested aren't capable of capturing
all the detail found in a 35mm color original under optimum conditions
(tripod, mirror lockup, etc.). In our tests, the highest res we've found in
a 35mm color slide or negative is 77 lp/mm. The best 4000 ppi scanner can
capture about 60 lp/mm, about 25% lower. But that's perfect, because under
normal shooting conditions (i.e., handheld instead of tripod mounted), 60
lp/mm is about the best you'll ever get from an SLR."
Stan
=======================================
Photography by Stan McQueen:
