filmscanners: Nikon Scan DOES Vary LED Brightness

["Jawed Ashraf" <Jawed@cupidity.force9.co.uk>]

Well, in disbelief, I have just done a test.  With Nikon Scan 3.1.1 running
stand-alone.

Nikon Scan has four sliders for Analog Gain: Master, Red, Green and Blue.
They work additively, i.e. Red brightness equals Master + Red.

In my test I used a slide that I have lying around (i.e. I didn't use the
motorised film strip adaptor that I normally use, as I normally scan only
negs).  No autofocus.  No ICE, no GEM, no ROC.  No tonal curves.  No USM.
No crop.

12-bit scan depth.

CMS On.

Performed on an Athlon 1.2GHz, 512MB, Win98 PC.  Timings are from the time
the scan button was pressed until I could hear the scan mechanism start
retracting (which coincides with the "Performing Scan..." progress bar
coming to a halt, the message being blanked and the heading "No scanning
items" appearing).

Test 1: Analog gain set to 0.  Time 77s.
Test 2: Analog gain set to -4 (-2 on Master, plus -2 on each of the colour
channels).  Time 77s
Test 3: Analog gain set to +4.  Time 87s.

Looking into the scanner ***I could clearly see that the brightness of the
alternating Red, Green, Blue light differed with each scan***.  The light is
seen reflecting off the slide mount.

In test 3 the sound the mechanism makes is different from the other two
tests.  It has a more "distinctly-stepped" quality to it.

The sounds are like a continuous burr from a fine stepper motor and a
less-frequent thrum from a coarse stepper motor.  Each thrum sound is
accompanied by the light going off.  The light is off for longer in test 3
than in tests 1 and 2.  I estimate around 300 seperate thrum sounds are made
per scan (I counted!).

Maybe Nikon Scan 3.0 varied integration time.  Its scans of slides have been
documented as clearly inferior to 3.1 (Mike Duncan published some nice
graphs) in terms of OD and the shape of the curve produced.  3.1.1 certainly
isn't solely varying integration time to vary exposure.

Also NS, version 3.1.1, seems to write the file to disk much more rapidly
now than it did in 3.1.

Those legs were tasty - char-grilled with a mustard sauce.

Jawed


> -----Original Message-----
> From: owner-filmscanners@halftone.co.uk
> [mailto:owner-filmscanners@halftone.co.uk]On Behalf Of Arthur Entlich
> Sent: 26 November 2001 13:13
> To: filmscanners@halftone.co.uk
> Subject: Re: filmscanners: RE: filmscanners: VueScan clipping & flat
> images

>
> Boy, this thing has grown legs... I was the person who indicated that
> Nikon's manual states that the brightness of the LEDs is altered.  Ed
> came back with information that the info is not correct, and that the
> CCD exposure time is altered instead, in spite of what Nikon's manual
> states and he was able to prove this via his monitoring of the command
> flow between the scanner and software adjustments.
>
> I've quoted myself and Ed below.
>
> Art
>
>
> > In a message dated 11/21/2001 8:07:15 AM EST, artistic@ampsc.com writes:
> >
> >
> >> Nikon might be approaching the limits of linearity in the LEDs.  They
> >> also need to be able to have a range of brightness available
> to them for
> >> the "analog exposure" they offer.
> >
> >
> > No, Nikon scanners don't vary the brightness of the LEDs.  The
> > "analog gain" option in NikonScan only changes the CCD exposure
> > time.  I've traced the commands that NikonScan sends to the
> > scanner, and the field it changes is definitely the CCD exposure
> > time field.
> >
> > In addition, the scan speed is proportional to the "analog gain"
> > setting, which it wouldn't be if NikonScan were only changing
> > the brightness of the LEDs.
> >
> > Regards,
> > Ed Hamrick
> >
>
>
>
>
>