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Re: [OM] More scanning stuff [was Got a new (OT) squeeze; my poor pooch]

Subject: Re: [OM] More scanning stuff [was Got a new (OT) squeeze; my poor pooch]
From: Ken Norton <ken@xxxxxxxxxxx>
Date: Fri, 22 Jun 2012 09:37:47 -0500
> I think there's a way to do that for color neg film, but haven't cared
> enough to figure it out.

I photograph my target using even flash illumination. For
entertainment sake, I run through a sequence of over/under exposures.
I scan these target photographs and apply the IT8 grid over it,
getting the boxes all carefully aligned. Pretty easy to do.

I had built profiles using Joel's Kodak target slide and that was
extremely valuable to get my process flow in the neighborhood. But
doing my own profiles with my own cameras made a lot of difference. I
did so with both film and digital cameras.


> I think it really is a difficult problem. The same issues as in my recent
> treatise post about color scanning apply. Is
> one looking for a particular tonal distribution, regardless of film used? Or
> is one interested in letting the 'native'
> tonalities of the film/development come through?

We've been around this tree a few times before. But I've probably gone
somewhere in between. I love Velvia and Provia, for example. I select
and use those films for the very reason that they taint the scene with
their own colors. On the flip side, however, almost all other films
need to match some expected norm of identifiable colors and tones. I
see little value in negating the strengths of Reala and Portra, but do
find value in taming some of the nasties of Ektar 100.


> ...it should be possible to create a PS Action that
> tonally adjusts scans of that particular film to
> match the B&W part of the IT8 target pretty closely.

I've been bothered quite a bit by the lack of tonal separation in most
people's B&W scans. There just isn't the tonal smoothness that I come
to expect from it. I haven't quite figured it out, but it is something
that I've struggled with myself. That's why you see me post very
little B&W on my site. It's as though there is no Zones III-IV in the
photographs. It jumps from Zones I-II staight to Zones V-VI and then
again to Zones IIX-IX. But III, IV and VII are missing. I really see
it in Chris' and Nathan's scans. I love the images otherwise, but this
tonal hop and skip just doesn't look right to me.


> I don't see any point in RGB scanning, just makes bigger output files with
> three channels. As Ken says, some film
> backings have a color cast. So scan one in RGB, look at the channels,
> determine which one works best, and select that
> channel in VS for scanning.

Well, maybe it's the overscan that is helping. By averaging the three
scans together, of which each of the three are reading the film
slightly different, we might be reducing the grain aliasing somewhat.


> [A bit of caution for anyone using chromogenic B&W film, not silver based.
> To take advantage of IR based dust removal,
> you need to set Bits per pixel to '64 bit RGBI, which does indeed seem to
> take forever. That's because RGB takes one
> scanner pass - and IR a full second pass. There is actually no wasted
> scanner activity. You can leave Output at 16 bit
> gray to avoid a three times larger than necessary output file.]

Hmm. I thought that the 64-bit RGBI file maintained the IR as a
separate channel for the editor. If you let VueScan apply the IR
cleaning to the file prior to saving, you don't need this settng.
64-bit RGBI is only for when you want to apply it as a mask later in
post. There are times when this woul be advantageous, but Ed has
improved the algorithm so much that I rarely have to fix one of the
cleaning marks.

-- 
Ken Norton
ken@xxxxxxxxxxx
http://www.zone-10.com
-- 
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