[filmscanners] RE: Nikon LS4000 Depth of field

["Alex Zabrovsky" <alexz@zoran.co.il>]

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)


Regards,
Alex Z

-----Original Message-----
From: filmscanners_owner@halftone.co.uk
[mailto:filmscanners_owner@halftone.co.uk]On Behalf Of Tony Terlecki
Sent: Thursday, April 25, 2002 4:27 PM
To: alexz@zoran.co.il
Subject: [filmscanners] Re: Nikon LS4000 Depth of field


On Wed, Apr 24, 2002 at 11:59:16PM +0100, al@greenspace.freeserve.co.uk
wrote:
> Hi,
>
> I know there are regular posts about the limited depth of field of the
> LS4000 and one work around was to set the focus to some point
> between the centre and the corner of the frame.  (I believe this is
> how Vuescan focusses by default on this scanner.)
>
> Although I think most people accept this is a valid concern, I'm still
> unclear how effective this approach is in getting round the issue.
> So two questions for those who have used the LS4000.
>
> Firstly, does the setting of focus point in this way work for 100% of
> shots or are badly bowed slides still compromised?
>

No it doesn't because film can be bowed differently depending on the mount,
etc. You personally need to find how far from the focus plane is acceptable
for you and then take it from there. I sample various points on the film and
then make a decision. It's time intensive but by far the best method. I
also now do my best to ensure film is flat before scanning - I don't mount
film anymore and also try and flatten it out prior to scanning (weighting it
under books etc.). If all else fails then I cut the frame from the strip and
mount on a glass mount.

--
Tony Terlecki
ajt@mrps.demon.co.uk
Running Debian/GNU 2.2 Linux

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