I suppose I am being a PIA here.
If I designed a film scanner that required manual focusing for best
results in any but the most extraordinary circumstances, I would feel
quite incompetent.
- I would have control over optical design and thus depth of field and
field curvature.
- I would know the characteristic shape of film in slide mounts of
various kinds and in the strip film holder I designed.
- I could specify how film is placed in the scanner, so that the
emulsion side would be known.
- It is technically pretty easy to measure the location of the face of
the film., either at the center, or sampled across the frame.
Given that info, how in Heaven's name could I create a design that
didn't have proper focus across the whole frame? Sheer incompetence?
Bloodymindedness?
People have been building film scanners for some time now. Most
maufacturers, certainly including Minolta, have been through several
design generations. This is not, as they say, rocket science, just
rather common engineering.
My lowly Canoscan 2720 dpi scanner auto focuses perfectly every time as
far as I can see. Grain in the center is clear and and sharp as is grain
at the edges.
As far as I can see, anybody who has to manually focus their new scanner
is in one of the following situations:
- Has a defective scanner and should send it back for repair/replacement.
- Has a defectively designed scanner and should return it for refund. I
find it hard to believe this is true of the Minolta 5400, but who knows.
- Is operating the scanner incorrectly.
- Has become convinced to worry about correcting something that isn't in
error in the first place.
I know I would not stand for being charged good money for a scanner I
had to focus manually. Scanning is time intensive enough as it is,
without adding an unnecessary and time consuming task. Back it would go.
A highly opinionated Moose
Chris Barker wrote:
>Dear All
>
>I have taken more interest in the AF capability of my Minolta 5400
>scanner since Walt muttered dark imprecations about its needing to be
>focused manually. I now sometimes take Walt's advice and focus
>manually with the Minolta software. However, I have also taken more
>interest in the focus cross in Vuescan's Preview window. Ed Hamrick
>has confirmed that it is the place where AF will take place (it was not
>clear to me from the instructions for Vuescan).
>
>Accordingly, my recent practice of dragging the focus cross to a
>contrasty part of the image *has* been of practical in use in improving
>the focus of my scans. I still use Minolta's software when Vuescan is
>defeated by the colour of one of my slides or negatives (pretty rare)
>and so will focus manually.
>
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