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: David Scharf <email@hidden>
- Date: Thu, 21 Jan 2016 22:26:31 -0800
- Sun-java-system-smtp-warning: Lines longer than SMTP allows found and truncated.
Hi Mike,
I read the article just fine without a membership. Try again.
Dave
--
DAVID SCHARF PHOTOGRAPHY
*DAVID SCHARF PHOTOGRAPHY*
Scanning Electron Microscopy
Los Angeles, CA 90039
http://www.scharfphoto.com
On 1/21/16 7:57 PM, Mike Strickler wrote:
Ernst, the article you link to requires a paid membership to read it, unfortunately. As for Callier effect with color negatives, well, it would have to be a problem with the surface, presumably on the emulsion side, as dyes to not scatter light as do silver grains in black and white film. These surface effects are dramatically reduced by liquid mounting. Aliasing of the grain image, on the other hand image can greatly increase its coarseness. This is a product of sampling frequency and grain pattern, and certain combinations of fim type and aperture size/sampling rate can aggravate the effect. Contrary to common belief using a smaller aperture may actually smooth out the grain by avoiding the frequency at which the aliasing is worst. Why negatives and not positives? They have a sharper grain pattern than positive transparencies, that's all. I've had little trouble matching the look of sharp optical enlargements in digital prints made from drum scans of the same color negatives.
Message: 5
Date: Thu, 21 Jan 2016 17:15:19 +0100
From: Ernst Dinkla <email@hidden>
To: MARK SEGAL <email@hidden>
Cc: "'colorsync-users?lists.apple.com' List"
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Subject: Re: Does MF color slides scanning in 24 bit still make sense
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You mean the Callier effect as mentioned earlier in one of the messages. I
doubt that. Sure that effect could be introduced in scanner or slide copier
illumination but true point light sources + condensors are not used in 99%
of scanners but the drum scanners. The last can eliminate that effect again
with aperture control which in practice is similar to CCD scanner multi
sampling, the sensor resolution being below the scan sampling resolution.
That is baked in hardware wise in the Epson and some Umax models but can be
extended with Vuescan and Silverfast. For the Nikon scanners the multi
sampling is a choice in the driver software. Even lighting in scanners is
more or less impossible with true point light sources but (I imagine) a
flying spot.
In color negative film the elimination of the orange mask should not
compromise the dye color capture, noise will appear one way or another. For
color negatives discontinuous spectral lighting whether with LED or CCFL
light sources can actually improve the dye capture if the spectral spikes
are placed at the maximum dye densities and the sensor RGB sensitivity
aimed at the combination of both spike and dye density. Intensity per
channel controlled to get neutrality. Human observer has lost any meaning
there.
Color film should not create a Callier effect. The pepper grain effect in
scans made on the Minolta scanners etc could be reduced with an extra
diffusor in the light path but what actually caused it was not a Callier
effect but this:
https://luminous-landscape.com/fuji-pepper-grain-the-mystery-resolved/
The problem showed less with wet mount scans, as I wrote before film
emulsion surfaces can play dirty tricks in scanning. Small bubbles in
lenses have no influence, small bubbles in film do, I recall there was
actually a commercial film that relied on it: Vesicular film. Not lost in
obscurity I see: https://en.wikipedia.org/wiki/Vesicular_film
In the seventees I had a Durst M610? enlarger. Normally equiped with a opal
bulb tungsten lamp + 45 degr mirror + condensor lens. Fascinated by the
German Veigel enlargers with their projector lamp lighting I tinkered a
slide projection lighting in the Durst. Then adjust the overlap of the
filament + mirrored filament correctly. Creating übergrain prints William
Klein style. On cheap document paper. It had nothing to do with sharpness
and all with contrast. Not usable for color either.
Met vriendelijke groet, Ernst
Dinkla Grafische Techniek
Quad, piëzografie, giclée
www.pigment-print.com
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