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Thread: USAF-1951 drum scanned?

  1. #21

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    Re: USAF-1951 drum scanned?

    Quote Originally Posted by timparkin View Post
    resolution got better until 10 micron and then the grain/noise started hiding detail.
    Interesting that 10 micron value... this is just 50lp/mm spatial frequence, and this also is the top resolving capability of sharp films like TMX in low contrast conditions, so it arises the question that it could be due to aliasing with grain size of the Tabular layer for BW. (Also there is the low speed cubic layer under that resolves much more, 200, I think).

    It would be interesting to know if optimal aperture for CMS 20 it is the same or if 3um is better for it.

    Another interesting question it would be knowing best aperture for color negative films that have larger color clouds (reengineering made to perform well in those digital minilabs of the Frontier era) compared to Velvia/Provia.

    Just speculating if a matching grain/cloud size vs aperture can worsen things...

  2. #22

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    Re: USAF-1951 drum scanned?

    Thank you Tim.

    According to the Tango docs it has a variety of apertures, with automatically selectable by NC ranging from 185.5 micron (#20) down to 11.7 (#2). Apparently the 10 micron would be the #1 and it is selectable only when the Aperture values -X is dialed-in in the NC UI.

    SergeyT

  3. #23

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    Re: USAF-1951 drum scanned?

    Quote Originally Posted by Pere Casals View Post
    Interesting that 10 micron value... this is just 50lp/mm spatial frequence
    It's also the point at which a heck of a lot of 1990s transparencies hit 30% MTF response (including all the Kodachromes & Agfa Scala!) & the point that Kodak Tri-X of that era & a whole lot of C41 films hit 50% response. 30% response for transparency & 50% for negatives at 50 lp/mm seems to have been regarded as the threshold for a film to be perceived as having first rate 'sharpness'.

    From the 80s/90s onwards, a more holistic approach based around the MTF behaviour of films seems to have been of greater research interest than notions of ever-finer grain size (already achieved once controlled crystal growth & tabular grains were a reality) or high contrast resolution tests & I don't doubt that Linotype/Hell & subsequently Heidelberg were very much up-to-date on the imaging research in this direction & that most of the optical decision making was driven by MTF theory.

  4. #24

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    Re: USAF-1951 drum scanned?

    Quote Originally Posted by interneg View Post
    most of the optical decision making was driven by MTF theory.
    OK, but perhaps at one point optimization was made to get good MTF response of the scanned image, rather than "on negative" to obtain an optimal optic print.

    This is what I concluded, just my opinion:

    When digital minilabs were everywhere they had clear advantage aganist optical minilabs. Digital minilabs allowed easy image enhacement, but C-41 films had to be reengineered to deliver larger clouds to be easy to scan and to prevent cloud aliasing. (softer clouds but "solved" with some digital sharpening)

    Digitalization of minilabs was big business, a common machine was $250000 and they sold that at world scale...

    Chromogenic BW (BW400CN, XP2...) also was ideal for digital minilabs.

    Perhaps because that some films changed to be scanned better, this is Portra, Ektar, Fuji 160, chromogenic BW and all consumer films, while BW and slides remained without those changes.

    It may be because this that today BW and slides are more difficult to scan than Porta...

    Another film kind that may have moved to larger clouds is stock Vision 3, as they have to deliver a DCI.

  5. #25

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    Re: USAF-1951 drum scanned?

    Quote Originally Posted by Pere Casals View Post
    When digital minilabs were everywhere they had clear advantage aganist optical minilabs. Digital minilabs allowed easy image enhacement, but C-41 films had to be reengineered to deliver larger clouds to be easy to scan and to prevent cloud aliasing. (softer clouds but "solved" with some digital sharpening)

    ...Another film kind that may have moved to larger clouds is stock Vision 3, as they have to deliver a DCI.
    I think you've got this backwards - bigger clouds equals more aliasing, not less. The solution is age old - finer grain, smaller dye clouds! The variable aperture on some drum scanners is intended to allow a reduction of aliasing by increasing the aperture size to match the clouds/ grain.

    From an entirely subjective perspective, having scanned quite a lot of various generations of the 160 speed Kodak C41 films in the last few years from 90s Vericolor to current Portra160 (before anyone asks, all generally was processed close to time of exposure & well stored subsequently - mostly 120 & scanned at the same resolution & without sharpening of any sort) I can offer a few observations. Sharpness-wise, the current Portra 160 is definitely the most immediately perceivably 'sharp' out of the box - as the MTF chart suggests. Resolution-wise, from Vericolor it increases somewhat through the VC/NC Portra era - the NC3 I've scanned is perhaps a fraction higher resolving than the current Portra 160. Grain/ dye cloud aliasing again is worst in the Vericolor, drastically better in the Portras & the current generation seems about the same as the last of the NC's.

    The one change in the current generation of Vision3 & C41 films that does seem different to earlier generations is the red component having an MTF response closer to transparency films (to emphasise 'kodak' reds & general colour scheme?). Contra to the received wisdom about ease of scanning, BW & transparencies are easier, even now - as long as you have a scanner with competent Dmax & reasonable manual controls - colour neg is relatively demanding of the operator's abilities to get correct colour. That said, photo engineers generally say that colour neg delivers more accurate colour than transparencies - and if you get Fuji 160s/NS to invert correctly, you see what they mean - it can be boringly, almost digitally 'accurate'!

    The current generation of Vision3 50D seems a bit of a joker in the pack with an MTF that seems almost transparency-like - the others seem more 'normal' in their behaviour - unlike Vision2 which attempted to seemingly offer a different film for every possible application. All this is quite astonishing, considering that before the mid-late 1980s, there was pretty much one colour negative film for professional cinema work, latterly rated at 100T, & pushable by a stop or so...

    It's also important to remember that ECN-2 films are designed to print to another film, not paper & that DI stages (ie scanning etc) have been commonplace since the 1990s, so claims about Vision3 being optimised for scanning are moot. Indeed, Kodak made negative films specifically for scanning at several points in the last couple of decades - & withdrew them because they weren't popular enough!

  6. #26

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    Re: USAF-1951 drum scanned?

    Quote Originally Posted by interneg View Post
    I think you've got this backwards - bigger clouds equals more aliasing, not less.
    You share a very interesting experience.

    Anyway I'd like to discuss the statement I quoted...

    My view is the counter: larger clouds equals to less aliasing. IMHO the benefit of larger clouds is cloud overlaping.

    This is my reasoning: If you have an smooth subject (like skin or blue sky) you can have two situations:

    1) Non overlaping small (and more color intense) clouds, then you will have aliasing with small aperture at the drum (or at the nikon 9000) because you can read on a cloud or between clouds. This delivers an undesirable grainny look.

    2) Larger overlaping clouds, aliasing problem related to cloud size disapears, you can scan with higher dpi sensor/optics or smaller drum aperture with lower aliasing.


    So what I introduce in the debate is what happens from the way clouds overlap...

    If clouds are not overlaping we have two kind of noises: luminance noise and chroma noise. If clouds from different layers do not overlap well then the scanner may read a lot of color noise, as color signal also aliases.

    This is just an opinion...

    You are right, if we view the MTF graphs from Velvia 100 and Fuji 160 we see comparable graphs... but the shape of the graph is quite different, much more curved in the 160 case, it is an interesting difference...
    Last edited by Pere Casals; 30-Nov-2017 at 10:41. Reason: typo

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