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[filmscanners] Re: Nikon LS4000 Depth of field

At 02:00 26/04/02, Alex Z wrote:
>I wonder whether the IV ED also suffers from this problem since I suspect it
>has almost the same hardware (except of the sensor).
>In fact, I remember noticing uneven sharpness descending near slide mount
>edges, but wasn't sure this is scanner's fault or the slide has been exposed
>that way (didn't have time to check the original under the loupe or play
>with manual focus point adjustment then)

Yes AFAIK all Nikon scanners are the same - must be Nikon's design choice
to use relatively large aperture lens, perhaps to make up for lower light
output from LEDs?

I don't know why they don't make the lens variable aperture, since they
seem to have at least 2 stops of extra light (or exposure anyway, maybe it
is partly extra exposure time) available using analogue gain control.  Why
not stop the lens down 2 stops and use max analog gain for normal exposure
operations?  Then you'd get a significant increase in Depth of Field and
greatly reduce the unsharpness problems at edges and corners.

If you want to check your scanner, I describe an easy way on


I'd be interested to hear your results on a couple of typical negs/slides,
and also interested if you have trouble with the complexity of my
instructions.  I've had one person tell me they couldn't understand it, but
a number seem to have found it useful so I am wondering if I need to
re-word it.


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