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[filmscanners] Autofocus-problems of Nikon LS-4000 with SF200 solved :-) was RE: Nikon LS-4000ED Depth of Field Revisited

Dear all,

After about one year of sending one LS-4000 after the other to service
over and over (in total I changed it 3 times and sent each one for
service 2-3 times...) I found out myself how to improve the autofocus in
combination with SF200 dramatically:

I noticed that the roll-fimholder, the manual one and the strip adapter
gave me far less trouble. So what do they have in common:

The scanner is in the upright position!!! Yes, it's that simple!!!

Use the SF200 with the scanner in upright position (you need to tape a
credit card or something similar inside, so the slides do not fall out)
and the autofocus suddenly works really well!!!

Apparently it's not really engeneered for being used layed on it's left
side mechanically.



> -----Original Message-----
> From: filmscanners_owner@halftone.co.uk
> [mailto:filmscanners_owner@halftone.co.uk] On Behalf Of
> Julian Robinson
> Sent: Friday, February 07, 2003 12:48 AM
> To: andreas.wistuba@t-online.de
> Subject: [filmscanners] Re: Nikon LS-4000ED Depth of Field Revisited
> Derek - you have gone to a lot of trouble to compare the
> focus performance of the two different holders for your
> scanner, but it is really hard to draw conclusions or interpret this.
> Can I suggest that to get a more direct comparison, just
> stick a film in each holder, and measure the 'auto' focus
> position at several positions including at least each corner,
> at the middle of each side, and at the centre of the image.
> This will give you at least 9 focus positions.  If the film
> was perfectly flat and perfectly aligned to the scan path,
> all these numbers would be the same.  If the film is curved
> or not parallel to the scan path, the numbers will vary.  The
> amount of the variation tells you the DOF you would need to
> correctly scan the image so that it was all in focus.
> In the end you get only one number for each holder - the
> total variation in focus position (= the range of these
> numbers)- which is easy to compare with the number for the
> other holder.
> When I did it, I got a total variation of over 60 nikon focus
> units for the auto feeder, and at best around 20 for the
> manual holder.  SInce my DOF is about 12(critical) to 20
> (acceptable) this means that I have a problem with anything
> except the manual holder on its best behaviour. I have
> swapped scanners since then and the new one is somewhat better.
> Julian
> At 18:37 06/02/03, you wrote:
> >Julian,
> >
> >I went back and used your methodology described below to
> determine the
> >critical focus range of my LS4000 and my results seem to be
> generally
> >what you thought they might be.
> >
> >Namely, critical focus is still intact at -5/+5 Nikon Units
> from focal
> >point (0).  Somewhere between -5/5 and -10/10 it softens enough to
> >remain within acceptable focus, but by -10/10 it seems to be clearly
> >out of critical focus.  By -15/15 the focal shift is significant.
> >However, one
> >caveat:  all my above determinations are being made when
> viewing a very
> >small portion of the total 24mm x 36mm image and at a highly
> magnified view.
> >
> >Given this, I am still hard pressed to say what would really
> appear as
> >out of critical focus when the total image has been printed, at lets
> >say 8x10, 11x14, 16x20, and viewed in total.  Tough to say.
> A bit of a
> >slippery slope, really.
> >
> >However, if one is going for the most pristine, most ideal
> scan and one
> >wants to make sure that even a small selection of the total image is
> >printed at a decent size, I would imagine one would want
> film curl not
> >to range outside of the -5/5 range if possible and definitely not
> >outside the -10/10 range.
> >
> >To this end, I have been considering using the slide mounts with
> >Anti-Newton glass as quite a few posters have mentioned previously.
> >However, results appear mixed.  Some say it works very
> nicely for them,
> >keeping film flatness within a 0-3 Nikon Unit range w/o any loss of
> >image clarity and sharpness.  Yet, others seem to indicate
> this is not
> >the case at all, claiming that the scanner even picks up the
> diffused
> >patterns characteristic of the AN glass.
> >
> >What have your findings been in this area?  I would be very
> interested
> >to hear.
> >
> >Lastly, I would like to post my DOF test results as they
> relate to the
> >FH-3 manual strip holder vs. the SA-21 auto strip feeder.  And here,
> >I'm afraid my findings still tend to stand out as anomalous.
> >
> >The reason here being that I pretty clearly got better DOF
> results (in
> >direct enlargement to enlargement comparisons) with the SA-21 Auto
> >Strip Feeder than with the FH-3 Manual Strip Holder.
> >
> >I ran the tests on 2 different images: one was on the inside
> of a film
> >strip and the other was on the end of the strip.  Each one
> was scanned
> >with the SA-21 and the FH-3 adapters (in both the LS4000 UPRIGHT and
> >orientations) and then compared at various view sizes and at
> various DOF
> >settings.
> >
> >Here is the side by side breakdown of the results (granted, this is
> >ultimately a subjective determination):
> >
> >
> >At Focal Point (0): SA21 sharper than FH3
> >(Side and Upright about the same sharpness; Side perhaps a little
> >sharper).
> >
> >At (+5): SA21 sharper than FH3
> >(Side clearly sharper than Upright).
> >
> >At (-5): SA21 sharper than FH3
> >(Upright now sharper than Side).
> >
> >At (+10): SA21 sharper than FH3
> >(Side especially sharper; Upright closer to FH3)
> >
> >At (-10): SA21 sharper than FH3
> >(especially Upright; Side better than FH3, but not as sharp
> as Upright)
> >
> >Summary:
> >
> >SA21 sharper than FH3 at all dofs. Side and Upright alternate; Side
> >sharper at focal point and points above; Upright sharper at points
> >below focal point.
> >
> >
> >
> >
> >At Focal Pt (0): FH3 a little sharper than SA21 in some places.
> >
> >At (+5): SA21 becomes a little sharper than FH3 in some places,
> >otherwise even.
> >
> >At (-5): FH3 clearly sharper than SA21
> >(except at lower left corner)
> >
> >At (+10): SA21 clearly sharper than FH3
> >(except  at lower left corner)
> >
> >At (-10): FH3 clearly sharper than SA21
> >(except  at lower left corner)
> >
> >Summary: SA21 and FH3 alternate at differing dofs; FH3
> sharper at focal
> >pt and at points above, while SA21 sharper at points below focal pt.
> >
> >Regards,
> >
> >Derek
> >
> >
> >----- Original Message -----
> >From: "Julian Robinson" <jrobinso@pcug.org.au>
> >To: <golder@netzero.com>
> >Sent: Saturday, January 25, 2003 1:26 PM
> >Subject: [filmscanners] Re: Nikon LS-4000ED Depth of Field Revisited
> >
> >
> >Hi Derek,
> >
> > >In the web site above, critical focus is maintained with a +/-12
> > >Nikon unit range, and decent focus within a +/-24 range.  How this
> > >translates to the LS4000, I don't know.
> > >
> > >I have looked at the scans super magnified and tried to
> discern what
> > >makes for a critical focus range in the LS4000 and what
> makes for a
> > >decently focused range (using NikonScan focus units) by looking at
> > >grain structure, but I fear I have not been to successful
> with this
> > >method.
> >
> >I was very interested to read your comments - it is good to
> hear that
> >at least some examples of the LS4000 seem to work well re focus.  As
> >Peter said, the extent of the focus problem definitely
> varies a lot of
> >between individual scanners.
> >
> >But I am bothered that you couldn't determine the critical
> focus range
> >- particularly since I have been waiting for a year or so
> for someone
> >to do this on an LS4000!!  (it was my page you were looking
> at).  Can
> >you have another go?  It would be very instructive for
> LS4000 owners,
> >of which I am not one, and also for me to know if the LS4000 is an
> >improvement over the LS2000 in this respect.
> >
> >It should be easy to do, unless I am missing something about
> the LS4000
> >that interferes with the method.  Let me try another
> description to see
> >if it helps. Pls don't be insulted by the level of detail, I
> am trying
> >to make sure we are doing the same thing.
> >
> >1) Use a negative, neg is better because scans have more
> apparent grain
> >to play with.
> >2) Do a preview and crop the image on the preview to be a small area
> >around some part of the neg with obvious grain
> >3) Do a "manual autofocus" on that point, read the focus number in
> >Nikon units - call your reading X.  By "manual autofocus" I mean :
> >
> >          - hold down on the control or command key and click on
> >             the focus button (the one like a checkered flag)
> >          - now click on your test area on the preview (the cursor
> >             should have changed to a gunsight)
> >
> >4) Scan, save the scan and enlarge in PS or whatever.  Note that the
> >grain is sharp.
> >5) Now, manually set the focus point to X + 5 or 10 units.
> To do this,
> >type the required value directly into the "Manual Focus
> Adjustment" box
> >on the Scanner Extras palette.  Repeat the scan and check if
> the grain
> >is still sharp.
> >6) Repeat 5) as often as necessary increasing the focus point value
> >each time, (moving the lens more and more away from the
> correct focus
> >point) until the resulting scan has clearly lost grain sharpness
> >7) Repeat 5) and 6) but this time setting the focus point to
> LESS than
> >the auto-derived focus value (i.e. X-5, X-10 etc), until the image
> >again has definite soft grain.
> >8) You should now have a series of little images with names
> like "+5",
> >"-20".  Line them up in Photoshop or whatever, in order, and
> pick the
> >two (a plus value and a minus value) at which the grain
> first becomes
> >definitely soft.  The difference between them is the DOF in
> Nikon units
> >- to grain sharpness level.  I did the same exercise again,
> but looking
> >at the *image* sharpness disregarding the fact that the grain was
> >obviously soft and got another figure - a greater range - over which
> >the image was acceptably sharp for my purposes.  This gave
> me a kind of
> >"worst case" - the actual range which I had to keep my film
> within if
> >the image was to be usable.
> >
> >The first time you do step 5, I suggest you choose an
> outlandish figure
> >like X + 50 just to check that the method is working.  If
> the resulting
> >test image is not way our of focus then there is a problem with my
> >description.
> >
> >Hope this helps, because it is not much use knowing the curviness of
> >your images if you don't know the scanner DOF.  I look fwd to your
> >results.  If any other LS4000 user has done this measurement can you
> >tell us your results pls?  (Or LS2000, 30, 8000 for that matter).
> >
> >Julian
> >
> >
> >
> >-------------------------------------------------------------
> ----------
> >-----
> >------------
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> >
> >
> >
> >
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> Julian
> Canberra, Australia
> Satellite maps of fire situation Canberra and Snowy Montains
> http://members.austarmetro.com.au/> ~julian/cbfires/fires.htm
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