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Re: filmscanners: Scanner resolution (was: BWP seeks scanner)



OK, did I miss something significant here, or did the subject just get 
changed? I'm *assuming* that "a resolution of 75 lp/mm" refers to 75 lines 
per milimeter--in which case the "/" is redundant. But of course, film has 
no lines per anything, it just "is".  Measurable, of course, but any "lines" 
are artificial.

Otherwise, I have this all wrong and don't know what anybody's saying on 
this topic. Clarifications? Please? Anyone?

Best regards--LRA


>From: BHannaford@aol.com
>Reply-To: filmscanners@halftone.co.uk
>To: filmscanners@halftone.co.uk
>Subject: Re: filmscanners: Scanner resolution (was: BWP seeks scanner)
>Date: Fri, 15 Jun 2001 13:27:40 EDT
>
>In a message dated 6/15/01 11:53:29 AM Eastern Daylight Time,
>Paul_Chefurka@pmc-sierra.com writes:
>
><< 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.
>
>  Paul Chefurka >>
>
>Here is an interesting observation from Michael J. McNamara (PopPhotgraphy
>July, p58)at the conclusion of the article on their scanner tests: "...Even
>the best 4000 dpi 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 
>all
>you'll ever get from an SLR."
>
>Whatever the theoretical merits of McNamara's observations, it appears to 
>me
>that they clearly are in agreement with the conclusions by Paul and  
>Raphael.
>  BTW, the 2900 ppi Nikon CoolscanIV resolved 53.3 lp/mm vs 60 lp/mm for 
>the
>CoolScan 4000ED; does this imply that it "outperformed" the more expensive
>scanner on a relative basis?
>
>Bruce

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