Re: aliasing was Re: filmscanners: Review of the Nikon CoolScan 4000

["Dave King" <kingphoto@mindspring.com>]

Rob wrote:
> Dave wrote:
> >It seems to me from eyeball guessing that my LS-30 is resolving
grain
> >in 100 ISO films at roughly 40-80% distortion, which looks pretty
bad
> >on the monitor at 100% view.  800 speed color neg film does much
> >better at what I would guess to be roughly 25% distortion.
>
> I presume you're comparing 100ASA print film with 800ASA print film?
> (as opposed to 100ASA slide film)
> Out of interest, exactly which brand/types of film are you using?
> How did you judge the distortion?  Compared to what?

I don't see significant differences in grain at the print level
between 100 speed negs and chromes, and print level is all I really
care about.  I'm scanning a variety of films from my files etc, but
these days I tend to shoot mostly Fuji Provia 100, Astia 100, 64T, NPS
160, and NHG 800.  (I guess I like Fuji :)

My judgement is completely subjective and therefore probably not worth
too much.  (Take with a large "grain" of halide :)  I judged the
distortion by comparing the grain on monitor at 100% to how I think it
would look with no distortion, and to tonal areas in the same scan
with less aliasing distortion.  My ideas about how grain looks are
formed by seeing grain magnified in various ways over the years.
Generally, the grain in least aliased areas of 800 speed neg film
looks pretty close to no distortion with LS-30 scans, to my eye.

> >The silver lining to this cloud is aliasing distortion (with the
> >LS-30) looks worse on screen than print, IMO.
>
> I'd agree with this, although in some cases the amount of distortion
> (aliasing, grain, whatever you want to call it) is ugly at much
lower
> print sizes.  I have a panoramic print on my wall at work on Epson
> Panoramic Photo Paper - the ocean and beach looks fine, but the sky
> has an ugly brown discolouration caused by grain aliasing.  The film
> was either Fuji Superia 100 or Reala.

I'm not sure how aliasing distortion could cause color shift, but
since aliasing becomes greater at certain tonal transitions you may be
seeing the additive effect of two problems overlapping.  Does your
printer profile posterize blues?

> Generally however, the printer does tend to be more fogiving than
the
> monitor - the "grain" usually ends up less intense in a print.

Jon Cone suggests to avoid overemphasing grain when sharpening scans
(I suppose equally true for aliasing distortion), never use a radius
setting higher than 0.8.  That's the way I tend to work editing Agfa
T-2500 scans, but I usually turn on ICE and sharpening together in
NikonScan 2.5, and it seems about right to me.

Dave