RE: filmscanners: Nikon Scan & VS Negative dynamic range

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

>===== Original Message From "Austin Franklin" <darkroom@ix.netcom.com> =====
>> -----Original Message-----
>> From: owner-filmscanners@halftone.co.uk
>> [mailto:owner-filmscanners@halftone.co.uk]On Behalf Of Mike Duncan
>> Sent: Wednesday, September 05, 2001 11:20 PM
>> To: filmscanners@halftone.co.uk
>> Subject: RE: filmscanners: Nikon Scan & VS Negative dynamic range
>>
>>
>> >> Comparing NS3.1 with the Kodak print of the Max400 Stouffer dupe,
>> >> NS3.1 has
>> >> more dynamic range by at least two stops.  The print compresses the
>> >> brightest 2 stops and the darkest step is compressed.
>> >>
>> >> Mike Duncan
>> >
>> >What does the scanning software have to do with the dynamic range of the
>> >scanner?  Are you letting the software set your setpoints?
>>
>> The software maps the input range into the 8-bit video.
>> Different settings
>> in VS give different OD ranges.  Nikon negative setting is mapped
>> to give a
>> higher contrast than VS normal negative setting.  Of course you can adjust
>> this with brightness and curve adjustment.  NS3.0 has a different mapping
>> for Positives than NS3.1, the latter giving wider OD range.
>>
>> Mike Duncan
>
>Mapping the input data into 8 bit values has nothing to do with the dynamic
>range of the A/D data.  That 8 bit data can represent any dynamic range at
>all.  In fact, three bits can represent any dynamic range at all.  It is the
>resolution within that dynamic range that the 8 bits gives you.

Yep, agreed.  Not rocket science.

>
>Curves are different than setpoints.  If you are seeing reduced dynamic
>range, the setpoints are not being set correctly, or are being set
>differently.  If the software allows you to set the setpoints manually, you
>will be able to get the exact same dynamic range from any software.

Yes Nikon Scan allows you to set the black and white points (levels sliders, 
curves and master/R/G/B brightness) but "the mix" of settings you can make *in 
combination* with NS's Auto Exposure "on" setting, prevents you getting all 
the range from a neg with a large dynamic range.  It's really that simple - 
I've spent hours tweaking the whole thing.

(When I turn off Auto Exposure the scan comes out irreperably coloured - I've 
tried and tried and I can't fix these scans - they are bizarre beyond belief, 
and I've built some funny looking curves trying to fix them - anyone got this 
working?)

You can adjust brightness when scanning a neg within the range -0.75 to +.5 
(ish) before the losses (shadow blocking or highlight scorching) become so bad 
that the exercise is pointless.  I have Supra 400 and Fuji Superia 200 negs 
that NS simply cannot get the full DR out of, no matter how I tweak 
brightness, curves etc.

Fundamentally NS gives you a restricted range of "setpoints", which 
unfortunately fall within the DR of negs - not by a huge amount, but enough to 
upset a purist/perfectionist.  NS always seems to clip the white point.

90% of negs (guess, maybe it's 95%, 99%, dunno) don't have such a huge DR that 
NS can't get all of it, so it's not actually a disaster.

My old Primefilm 1800 and its accompanying software did, at least, allow me to 
adjust the setpoints WAY outside of the DR of negs - unfortunately it was 
relatively noisy and grain-aliased like a champion (in comparison with the 
LS40, anyway).

Jawed