Rob wrote:
>I wonder
>if the Nikon focusses more accurately on the *surface* of the film hence
>it tends to show surface defects more? Has anyone tried manually
>adjusting the focus a little to see if it's possible to defocus the dust
>and scratches without losing too much sharpness in the image?
Accurate focus should be on the *emulsion,* not on the "surface" (of which
there are two--front and back). Rob knows this, of course, but it might be
confusing to new list members.
Scratches and dust can show up from either surface of the film, but the *worst*
ones will be on the dull elulsion side. Scratches there actually destroy or
alter the image, and dust has a nasty tendency to fuse to old film, as has been
discussed here before.
"Softer" focus will also soften dust, scratches (particularly those on the film
base) and grain-aliasing, but won't actually eliminate them. Film grain is
*smaller* than most dust and scratches (but not particulates), so it is more
readily reduced by defocusing. This is essentially what you do when you use a
dust or despeckle filter in your favorite imaging program. A very good filter
algorithm will isolate what is obviously dust or scratch (i.e. a marked
contrast with surrounding pixels), and leave fine details alone, whereas
defocussing or blurring is global. It bears noting that not all filter
algorithms are that good, and none of them are perfect, in my experience. If in
doubt, Save first.
Best regards--LRA
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