Lets get this straight. If a film has curvature of field then by and
definition you care to name you will get image distortion of one kind or
another.
I would suggest that if you are prepared to accept edge distortion, because
it has little if any effect on the subjective impression of the actual
picture, you should also be totally unaware of any loss in definition at the
edges.
( will you kindly note that cropping has yet to be introduced into the
equation and it might just be that such an action renders all your chat
totally irrelevent)
On the other hand if image sharpness at the edge of an image really matters
that much then so will image distortion.
I would claim that distortion is the worse of the two failings and as such
the correct solution of using glass applies, as it does in all other
matters.
I might also point out that comparing the Nikon scanner with the Polaroid
Sprintscan 120 is utter nonsense because in the UK a typical asking price
for the Nikon is £1299.00 while for the Polaroid it is £2,899.00
I would suggest that it is easier and cheaper to put glass around a film
image than it is to fork out the additional £1,600 not to have to so do.
----- Original Message -----
From: "Peter Marquis-Kyle" <petermk@optushome.com.au>
To: <dickbo@btopenworld.com>
Sent: Friday, April 26, 2002 5:37 AM
Subject: [filmscanners] Re: Nikon LS4000 Depth of field
I would like to commend Julian Robinson's method for measuring film flatness
and
depth of focus:
If you have a Nikon scanner you should do the tests he describes. Use a
variety
of different film stock, and test the different film holders. You will then
know
what is sharp and what is not-quite-sharp.
At best, you might spend an hour testing, and find everything works
perfectly.
At worst, you could find the scanner is seriously out of alignment and needs
to
be sent back for fixing or replacement.
My result (with an LS-30) was in between: I found that the motorised film
strip
feeder did not reliably hold every part of the film within the zone of sharp
focus. So I know to use the film strip holder instead, except for quick and
dirty scans of a bunch of negs, when the motorised feeder is OK.
Thanks again, Julian.
Peter Marquis-Kyle
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