3 Attachment(s)
Color Transparency film 18% gray card test (expanding on "be technical perfect ?")
Again, another discussion devolved into personal attacks and ego driven hostilities..
https://www.largeformatphotography.i...hnical-perfect
From all that egocentric blather text has some text worthy of expanding on:
Quote:
Originally Posted by
Drew Wiley
Color film is a different topic because it is basically center-out from "gray card". Hue saturation and tonal value are entirely interconnected, and not an abstract gray scale gradation like in b&w photography. Sure, anyone can bend the rules as they please; but when we speak about color film it's customarily in the context of color printing too. Yeah, just this past year I've made a number of very nice b&w prints from both color chrome originals and color neg originals, jumping through the appropriate interneg/interpositive hoops of course. But when we stick to color printing per se, deviation from box speed generally comes with some kind of penalty, often severe. The days are long gone since the old moth-eaten advice to overexpose color neg film made sense, or to underexpose chromes.
Back in the days of "proper" color transparency images required 18% gray card testing of the specific film and film production lot combined with lighting, lens, E6 processing, color temperature of the light used to view color transparencies and more.
~These are absolute reference points folks.~ ala, the "rules".. Now, once these rules are established and deeply understood, then the rules and all that can be bent, distorted and more to achieve a given creative-expressive image goal. Any less will result in happenstance_chance-a-stance and plenty of entropy.
This is a sample Agfachrome RS100, 8x10 color transparency 18% "gray card test" done at The New Lab back in the days when this was a common daily happenstance by plenty of Photographers striving to provide their clients with the best possible color transparency images. Conditions related to the creation of this "gray card test" sample:
~AgfaChrome RS100, 8x10, spec ISO = 100. Emulsion lot# 1520.
~Elinchrom 404 power pack, Elinchrom S flash head.
~Bronocolor soft box.
~Macbeth color checker, less than one year old.. these thing degrade with age/time.
~14" f9 Goerz APO artar RDA) lens.
~Minolta flashmeter IV, checked for calibration.
~Sinar 8x10 camera as needed.
Attachment 228716
Density numbers on the gray card work sheet is produced with a calibration certified X-rite transmission color densitometer at The New Lab using their "Normal" E6 process.. which The New Lab did wonders to keep consistent hour after hour, day to day, week to week, month to month and the passage of those years until The New Lab died.
Attachment 228717
Note the ~Red~, ~Green~, ~Blue~ density numbers and the Color Compensation (cc) filter number suggested to bring the overall color balance of the entire image creation system close to neutral color balance. In this specific case, a 025cc Green filter is suggested to null out the +4 density reading of the Green density channel.
This gray card test color transparency also note the optical performance of the 14" f9 Goerz APO artar, which is simply excellent in every way from resolution to color balance with moderate contrast rendition. This is the place where the lens was focused.
Attachment 228718
~This will produce essentially neutral color balance image in the color transparency film for the conditions listed above. Deviate from any of these conditions, the color balance will change. Once this point of reference is know and set, then the "rules" and all can be bent and deviated from under control, not random happenstance_chance-a-stance. Doing a search today on Google produces ZERO results for this specific gray card test. Seems today, if the item cannot be found on Google, it is not real and never happened, never existed... except Google is not "know it all" nostradamus...
The other MAJOR issue with color images is humanoid color perception which is "self compensating" AND requires proper training/experience/lots of real world practice to understand humanoid color perception bias and self deception. Take the time to read this Kodak publication on color:
https://www.kodak.com/content/produc...olor-Image.pdf
Copy pg. 47 of that Kodak publication on color
"COLOR QUALITY OF ILLUMINATION
Though virtually negligible in black and white photography, the color quality of the light source is an all-important consideration in color photography. Essentially, the problem in color work arises from the fact that a color film does not always “see” colors as human beings see them. For example, if the cover of a book appears green in daylight, that is, in illumination which is a combination of sunlight and skylight, we think of it as having the same color in tungsten light. Although the difference in the quality of the illumination actually effects the quality of the light reaching the eye, our vision automatically compensates for the change. A color film, having no such automatic compensation, reproduces color approximately as the eye sees it only when the illumination is the same as that for which the film is balanced.
~Contemporary photography accepts artistic license in the use of light sources which do not necessarily match the film’s color sensitivity.~"
Again, knowing AND understanding the "rules" has meaning and content.
Third, Tim Hall produced a good series on color found on YouTube..
Color Correction and Sensitometry - Part 1
https://www.youtube.com/watch?v=Mss_EnQsq0o
Color Correction and Sensitometry - Part 2
https://www.youtube.com/watch?v=P5x7TDsHRV8
Fourth, Behavior of color film due to interactions of color layers and innate color rendition, color balance, contrast, hue does NOT mean ALL ooopsies can be fixed-up in Foto software, why?
Or why color film stopped years ago.
Bernice
Re: Color Transparency film 18% gray card test (expanding on "be technical perfect ?"
Color film is better than ever in terms of quality control, esp color neg film. I count on this fact all the time. And the current E100 chrome is better balanced than the majority of its predecessors. NO, it's not a substitute for Astia at the peak of its evolution as Astia 100F, or for certain old classics like the Kodachrome line; but it's a very good general-purpose product, and in my careful tests at least, spot on 5500K balanced and true 100 box speed.
Personal color perception is an acquired skill, and only half physiological; the other half is psychological and requires quite a bit of experience and training using the right kind of comparison tools and lighting etc. I've trained pro color matchers. No color photographic medium is perfect; nor will there ever be such a product. It all depends. I'm well aware of what bending the rules does; I've done plenty of that myself, often just to learn where the real boundaries actually are.
The MacBeth Color Checker Chart is a superb tool; but not many people know how to correctly use it. But if someone can capture it as precisely as possible on their film to create a master neg or chrome under tighly controlled color temperature and correct exposure, and output it in their preferred print medium, with all the gray scale truly neutral gray, and all the RGB primaries, as well as CMY secondaries, singing with the same intensity and purity at the same time, they're on the right track. The tertiary patches should fall into line too, though no film ever invented will do all of them perfectly. Some of that can be corrected via masking or digital substitute, but only up to a certain point. And no matter how good you get at it, you can't overcome the persistent enemy of metamerism if a print is displayed in significantly different illumination than your lab standard.
But once you've got all that under control, your journey has just begun. It takes time to learn the specific personalities of different color films. Most CN films are balanced with skin tones in mind, and have a certain amount of deliberate dye curve overlap. An unwanted side effect of that is that it tends to dump related hues into the same bin, and not cleanly differentiate them. Ektar is a different animal and capable of delivering results analogous to chrome fim; but there are a few tricks to it, and those who are on the religious side of paying close attention to the color temp of scene illumination, and expose as carefully as if it were a chrome film, are going to get the most cooperation out of it.
