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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