Re: Does MF color slides scanning in 24 bit still make sense
Re: Does MF color slides scanning in 24 bit still make sense
- Subject: Re: Does MF color slides scanning in 24 bit still make sense
- From: Ernst Dinkla <email@hidden>
- Date: Wed, 20 Jan 2016 18:04:06 +0100
B&W films usually have more matte emulsion surfaces than color films have.
Wet mounting at least reduces the light scattering of matte emulsion
surfaces. Grain in scans is aliased grain when the scan is made on CCD
scanners, that noise can however be decreased in more ways, multi sampling
for example helps to reduce noise of whatever kind. (Tim Vitale claims it
is aliased on any scanner) What I find problematic in editing scanned B&W
film is that the image contrast as seen depends on both pixel data and
aliased grain formation. The sharpening and (micro) contrast tools need
more subtle control than with original digital images or one has to take
out the grain right away. Usually I try to keep some grain while editing.
In my experience with MF and larger on film and desktop scanners the main
advantage of wet mounting has been a more even focus all over the frame and
a more even light transmission. In editing then the sharpening tools at
least create equal changes over the image area, again with that "grain" as
a second image component. With the Nikon Coolscan 8000 the carrier + wet
mount film holder still showed differences in focus per scanned frame as
the film holder shifts from one end to the other in the carrier and is then
not kept horizontal enough to my taste. Tweaked the holder + carrier for a
compromise. On the even light transmission, a warped film transmits light
uneven along the scan path, I think this may show quite fast even with 35mm
strips in a normal 6 frame holder
I wonder whether the light source of a slide duplicator is aimed well
enough at the RGB filtering of the digital camera sensor to get the best
gamut etc. The sensitivity of the duplicating color film must have been
aimed at the available media + light sources then, DSLRs not so far.
Sony sensitivity A7R (etc?) 600 520 460 nanometer
Fujichrome sensitive at 640 550 445 nanometer
Fujichrome dye density at 660 550 445 nanometer
Kodachrome sensitive at 650 560 450 nanometer
Kodachrome dye density 640 540 445 nanometer
The film numbers taken from the peaks in the documentation graphics.
I also wonder whether RGB LED strips used by the guys that made the XY
camera copy scanners do not make this worse if the RGB LED strips are of
the narrow bandwidth type. I understand there are "RGB" LED strips that
have three kinds of white LEDs aboard. For B&W however the use of green
LEDs only near 520 nanometer should be ideal.
Met vriendelijke groet, Ernst
Dinkla Grafische Techniek
Quad, piëzografie, giclée
www.pigment-print.com
On Wed, Jan 20, 2016 at 4:26 PM, Martin Orpen <email@hidden>
wrote:
>
> > On 20 Jan 2016, at 01:11, Mike Strickler <email@hidden> wrote:
> >
> > Hi Martin. You know t's a funny thing, but grain does also get smoothed
> out quite a bit by the scanning oil. The effect is obvious when you look at
> the image inside an air bell (usually caused by some tiny particle lifting
> up the film around it. That part, which has no fluid on it, is definitely
> grainier looking, even when it's color negative film, which has no
> light-scattering silver grains and thus no Callier effect. I concluded that
> the minute swellings of the emulsion surface where silver grains had been
> before being bleached out are sufficient to scatter a bit of light, much as
> scratches do. Another good reason to wet-mount the film.
>
>
> I’m not convinced about that theory Mike :)
>
> Repairing air bubbles is a regular task, especially around the bite marks
> in 5x4, but darkening the bubble area (or lightening on neg) and then
> removing the edge is normally sufficient for a seamless repair. I don’t
> recall any occasion where we’ve had to soften the image because it has been
> more grainy after the curve correction? Although this may be because 99% of
> our scanning is from colour originals?
>
> Not sure that the Callier Effect applies to the benefits of oil mounting
> anyhow? The drum light source is fixed.
>
> Oil mounting ensures that light isn’t scattered as it travels through the
> negative or transparency.
>
> Under *any* backlighting source, oil mounted negs have more depth and
> contrast than dry mounted negs.
>
> Regards
>
> --
> Martin Orpen
> Idea Digital Imaging Ltd
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