How Kodachrome Narrow Band Cyan Dye helped to film produce garish colors ?

[Mustafa Umut Sarac]

Photo Engineer and all,

Could you please describe how Kodachrome Narrow Band Cyan dye help to film produce its - PE called Garish - colors ?

How does that narrow band cyan or other fundemental narrow band colors helps to for example National Geographics breathtaking colors at 1989 and how does it help to Leica sees reds as deep reds at every lens ?

I think there might be a connection between National Geographic Magazine Inks and Kodachrome because they were the worlds largest Kodachrome users 30 years ago. Ten thousands of rolls beeen processed every month at their lab. I think they made a ink to be able to publish the film.

Umut

 

[DREW WILEY]

Mostly, NG wanted their photographers to always carry red sweaters in their kit, so someone in the scene would always be wearing red. They're
still pretty boxed-in when it comes to photo editing, though the mandatory red days are long gone. But you'd probably have to specify the era
of Kodachrome. Most of it as any of us remember it was famous for its neutrality. Only an advanced color printmaker would recognize certain
dye foibles. I've seen early 5x7 sheet film Kodachromes from Hollywood studios that looked better than anything E6 today.

 

[Gerald C Koch]

PE would be best to answer this question. However the spectral transmission of a dye looks something like the standard distribution or bell curve. For color films the tail regions of the three dyes overlap to a greater or lesser extent. The narrow band for the cyan dye thus reduced the overlap effecting the colors and created the distinctive of look of Kodachrome.

 

[AgX]

The issue is not actually the bandwith, but the overlap between the curves of the dyes, or rather with complimentary sensitivity curves of the eye.
(Though based on a bell-shape a wider bandwith will typically result in shallow sides, which again facilitates overlap.)

Image dyes should have steep sides. What they have not...

 

[DREW WILEY]

The positioning of the peak of one dye curve in Kodachrome was, if I recall correctly, a bit off-center compared to its hypothetical nm target.
So a typical hard red color separation filter like a 29 would lop too much of the curve off for high-quality repro purposes. But the early Ektachrome suffered from more overlap contamination of the cyan with magenta, so required a "trimmer" type correction to one side. In fact, poor green reproduction was symptomatic with Ektachromes up until the E100S series. Most people wouldn't notice these idiosyncrasies on a
light box or slide projector, but it certainly came into play in any advanced level of printmaking. But I can only speak for my generation of
experience. Kodachrome had a considerable history before my time.

 

[AgX]

The peak of the Kodachrome Cyan dye is most located to the low side compared to ist contemporaries (of the mid 60's Umut is most probably refering to.)

 

[Mustafa Umut Sarac]

Thank you all, I read your all answers and I am grateful to you. I learned the narrow band cyan story from PE and I dont know whether he goes back to 60s or after his patent at 1972.

Gerald, your answer covers all answers , I want to learn how less overlapped cyan dye effects the colors , does it help to magenta to give pure reds , pinks and oranges for example ?

 

[Gerald C Koch]

You may find the following articles of interest.

http://www.kodak.com/global/plugins/acrobat/en/service/Zmanuals/z50_03.pdf
http://www.kodak.com/global/plugins/acrobat/en/service/Zmanuals/z50_08.pdf

In a perfect color process there would be no overlap between the curves and no gap between them. How the colors are affected is determined by which tails overlap and by how much.

 

[Mustafa Umut Sarac]

Blue density of the magenta patch—Magenta dye has a
relatively large amount of unwanted absorption of blue light.
That is why the standard aim value for the blue density of the
magenta patch is relatively high; the standard aim value
contains a large contribution of unwanted absorption by
magenta dye. Therefore, the blue density of magenta patch
can be influenced not only by yellow dye contamination but
also by fluctuations of the amount of magenta dye

 

[AgX]

In a perfect color process there would be no overlap between the curves and no gap between them. How the colors are affected is determined by which tails overlap and by how much.

A gap between the imaging dyes absorbtion curves does not matter, as long as there is sufficient overlap with sensitivity curves of the eye, or with the those of a further photographic material.