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On 18/08/2019 14:25, Brad Rogers wrote:
On Sun, 18 Aug 2019 14:12:48 +0100 Julian Hall <linux@xxxxxxxxxxxx> wrote: Hello Julian,* No mount thickness problems - all perfectly aligned.On a standard flatbed scanner, focus is at the contact of glass & item. If one leaves slides in their mount, focus will be off. Not by much, admittedly, but when trying to preserve as much data as possible..... That's true if you don't take depth of field into account1; my friend who owns the stand alone scanner I used pointed out that they only have a narrow depth of field - cheap ones are just webcams mounted in a box. You have the same issue with varying thicknesses of slide mount in a stand alone scanner - the ones I had were up to 2-3mm different in thickness, so further from the lens. Flat bed scanners have enough depth of field to still have crisp images even of slides. I've never had a problem with any slides scanned on a flatbed scanner. 1 The range from the lens at which an image is in
focus. The narrower the range, the more precise the object
placement must be from the lens for it to be in focus. |
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