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In message <214b5$445e66c7$3ea3eb6a$21938@news.chello.nl>, Ernst Dinkla
writes
>
>
>Alright, then it is the Epson manufacturing tolerance again. It didn't
>improve with the V700 and it probably is more of a nuisance now as I
>expect the DOF to be more limited in the optical system compared to the
>older models. Many users will now expect that the three choices of
>focus correction provided by Epson are covering the range and settle
>for the one that's closest to the real focus. A pity as that doesn't
>deliver the best quality on the scanners that are more off. In a way
>worse than with the old models where nobody knew what the focus shift
>could be and you had no expectation of its range.
Ernst,
At least they acknowledge that there may be a need to adjust the focus
plane.
My previous scanner was a CanoScan 8000F. It gave sharp reflective scans
of material placed on the glass and I wondered if the DOF was sufficient
to cover film in the film holder, which held the film 2 or 3mm away from
the glass. It wasn't
I ended up abandoning the film holder for negatives and scanning
directly on the platen surface, under a glass plate to maintain
flatness. Scans made this way were significantly sharper than scans made
using the film holder, but then Newton's rings caused endless problems.
It seems to me that flatbed scanners are all going to suffer from the
same problem; they have to have the plane of focus optimised for either
film in a holder above the glass, or material placed directly on the
glass. The DOF is never going to be enough to cover both.
The V700 does shift focus when scanning large format material without
the film holder; the lens that's used for this purpose definitely seems
focussed on the glass surface rather than 3mm or so above.
Alan
--
Alan Bridgewater
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