Message-Id: <mailto:199601221452.IAA16372@library.wustl.edu> Date: Mon, 22 Jan 1996 08:49:12 CST From: Philip Foster <mailto:PFOSTER@DOPIG.UAB.EDU> Subject: Re: Slide scanning To: Multiple recipients of list IMAGELIB
On Wed 1/17 Adrian Ashcroft asked:> 1. Is it better to remove a slide from its glass mount before scanning?
> i.e. Does the glass cause any distortion or reflections on the image?
Our experience says there is little to be gained by removing the slide from a glass mount, unless it is dirty. We occassionally get better center-to-corner sharpness on our Nikon slide scanner if the slide is glass mounted. Always check focus if maximum sharpness is critical.
> 2. What is the minimum DPI for scanning 35mm slides in order to have
> grain-level resolution?
A hard question to answer. It depends on the film emulsion and your scanner. We have 2 slide scanners: an older Nikon LS-3500 (4000x6000 pixels) and a Kodak RFS-2035+ (2000x3000 pixels). The Kodak is faster and produces "better" color and shadow detail, but the Nikon is sharper. How much sharper? Very little. So little that its not noticeable in almost any output format. It is noticeable with an 8x loupe or a microscope, but the average viewer generally prefers the scan with better color and dynamic range (the Kodak) over the higher resolution scan (Nikon).
In my opinion neither of these scanners can truly record accurately the grain structure of an ISO 100 transparancy film.
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Philip Foster, Director, Photography & Instructional Graphics University of Alabama at Birmingham, 933 19th St. S., Rm. 320 Birmingham, AL 35294-2041 (205) 934-4396 FAX 934-1000 mailto:pfoster@dopig.uab.edu http://www.dopig.uab.edu