Quote:
Originally Posted by triwak
Slightly off-topic, but does anyone know how to adjust a scanner to focus on the card, when being scanned inside a plastic holder (either a graded card, or in a screw-down)? I used to have an HP scanner that worked just fine. But my current Canon only focuses on the plastic actually TOUCHING the screen, thus making the card image blurry.
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It has to do with the type of scanning element used by the scanner (CCD vs CIS), not an adjustment of the focal depth. Generally speaking, scanners with CCD elements "see" more depth so that they can scan 3-dimensional objects (slabbed cards, books which do not lay flat on the glass, pins or buttons, even baseballs in some instances I've seen), whereas scanners with CIS elements generally require the object being scanned to be flat against the glass and are focused at that specific depth. I am not aware of any desktop flatbed scanner, of either element type, that allows the focal depth to be adjusted. Even with CCD scanners, if you wanted to optimize the scanning depth, you would need to raise or lower the object being scanned (as with the variable-height scanning trays for film scanning offered by betterscanning.com).