Is it possible for a particular color to fall outside of the Portra 400 gamut?

pentaxuser · Jul 29, 2023

Drew I presume that you have the negative from which you produced the huge picture. Is it not possible to use that to demonstrate how well your Portra 160 handled the purples as you described in your earlier post?

You often seem to have the proof that makes some of our posts on threads look like secondary nonsense but we never see it which is a great pity as currently we need a way to get to the bottom of how much Portra is at fault and how much the photographer is at fault as you seem to hint at.

So at least in simple terms can you say what it is that Steven needs to do in terms of steps to take to improve what he gets from Portra?

He has highlighted what he thinks is a problem with this colour on Portra and has given us evidence. The function of the forum is to try and see what we can advise him to do about it, isn't it?

If he had said from the start that as far as he was concerned, Portra 400 cannot render this shade of purple any better and he was seeking other means such as digital for such colours then the thread may as well have stopped there as his problem with Portra from his point of view was solved but I presume that is not his position. He is still looking for answers from what I can see

pentaxuser

eli griggs · Jul 29, 2023

DREW WILEY said:
Polarizers don't saturate color - they just remove the lovely reflections, and often skew the color itself. But if you want a postcardy look to fall colors, that's how a lot of people do it. Others resort to the warming fakery of neodymium filters.

Part of the greater issue is that different hues saturate at different points along the exposure scale. For example, a bright yellow saturates a full stop higher than typical green, and a stop or more higher than blue or purple. Yet such colors in nature itself are all over the map, and it takes actual experience, and not just a light meter, to know which hues to favor at the expense of which others, in relation to the specific film you have chosen.

Thus, I simply said "for better overall colour saturation... "

DREW WILEY · Jul 29, 2023

Polarizers skew the color, and tend to darken blue. I keep a good one on hand at the copy station in the lab. Shiny prints like Cibachrome need cross-polarized light to tame the reflections; but there's alway a penalty to correct color representation. That happens with glazed paintings too, when polarized light is necessary for copying work. But out in the field, you only have the polarizer over the lens to deal with, and not on the copy lights as well, so it can be used more gently. But then you're dependent on the angle of the sun.

eli griggs · Jul 29, 2023

Polarizer's skew colour, adjust, in that they remove excess light from the image for a truer presentation of the actual colours of an item.

Removing the extra or excess light from being reflected into the camera will, naturally, "darken" the colours, free of the 'pollution' of excess.

Alan Edward Klein · Jul 29, 2023

Here's a (digital, sorry) picture that used a polarizer filter at full. While the colors are saturated because the reflections on the foliage were removed, it kills the life out of the scene. I've found that modulating the polarizer and leaving some reflections is best.

eli griggs · Jul 29, 2023

Alan Edward Klein said:
"I've found that modulating the polarizer and leaving some reflections is best."

Which is why the polarizer needs to be manually set for the best results, intelligently.

That takes experience and an earned or natural
aesthetic, to bring out an interesting or technical point of view.

Simply putting on the filter does no mean you'll automatically get the best result, it's only the begining of the method.

Romanko · Jul 30, 2023

Steven Lee said:
It shows up fairly life-like on iPhone photos or photos taken with my Canon digital camera

Do you have the RAW file for this image? It should be possible to get a more definitive answer to your question. Here is a plan:
1. Read the RAW file, convert it to XYZ colorspace and sample the color in XYZ coordinates;
2. Use spectral sensitivity curves of Portra 400 to calculate the film colorspace;
3. Check if the color is within the film gamut.

koraks · Jul 30, 2023

Romanko said:
Check if the color is within the film gamut.

Hue recording and rendition goes far beyond the question whether the color is within a certain gamut. Your method won't yield a definitive answer for a variety of reasons.

Romanko · Jul 30, 2023

koraks said:
Hue recording and rendition goes far beyond the question whether the color is within a certain gamut.

I am not an expert in colorimetry. The original question was if the color is within the film gamut and I thought this simple test could give an answer.

koraks · Jul 30, 2023

I understand the line of reasoning, and it sounds plausible...until you realize how color perception works and that there are several ways in which a particular hue can be constructed, but also can fail to render as anticipated. Your test will only work within a very narrow set of conditions which are not applicable in the case of practical photography. See my first and (sorry) long response to this thread for a couple of reasons why this is the case.

Helge · Jul 30, 2023

Few people seem to know that a pol filter can also be used to enhance reflections. It will attenuate the rest of the scene and let through almost all of the reflected light at that particular angle.
Can be used to creative effect with diffusion filters and film with strong halation.

faberryman · Jul 30, 2023

eli griggs said:
Which is why the polarizer needs to be manually set for the best results, intelligently.

How else would you set a polarizer? Don't you just turn it around until you see the effect you want? It is not like it is rocket science. Are there polarizers for camera lenses that set themselves automatically?

Alan Edward Klein · Jul 30, 2023

faberryman said:
How else would you set a polarizer? Don't you just turn it around until you see the effect you want? It is not like it is rocket science. Are there polarizers for camera lenses that set themselves automatically?

Eli was trying to make the same point I was. That you just don't set it on maximum polarization as many, maybe most, photographers do. That's not necessarily the best position. It may be too much of a good thing.

BrianShaw · Jul 30, 2023

So it must be true... magenta is NOT a color.

pentaxuser · Jul 30, 2023

BrianShaw said:
So it must be true... magenta is NOT a color.

As they say in our Parliament: "I refer the honourable member for the West Coast to that now long but sadly never to be lost thread in Photrio on said subject of magenta" We are at our quaintest in the U.K. when we speak "Parliament"

pentaxuser

faberryman · Jul 30, 2023

Alan Edward Klein said:
Eli was trying to make the same point I was. That you just don't set it on maximum polarization as many, maybe most, photographers do. That's not necessarily the best position. It may be too much of a good thing.

How did you determine that "many, perhaps most, photographers" set the polarizer at maximum? Can you quantify "many"? And by "most" do you mean 50%+1 or something else? Sounds like your assertion relies on the logical fallacies of vagueness and hasty generalization.

MattKing · Jul 30, 2023

BrianShaw said:
So it must be true... magenta is NOT a color.

I'm hesitant to say it, but "great minds think alike".

As I've said so many times before, I wish PE was still with us.

wiltw · Jul 30, 2023

Steven Lee said:
My situation is that I noticed that one very specific color never shows up properly on my Portra 400 scans. It gets cooler and desaturated. The color is somewhere between pink and purple, maybe someone would be able to nail the name, it's basically the darker color of this girl's dress:

I have numerous other examples, with different light and different subjects. But it's always the pink/purple combo and always Portra. Could be a coincidence, I should probably shoot that dress on 5 different emulsions to make sure.

This can also be the limitation of my scanning. At the moment I sold all of my scanners and using the Sony A7R. I have access to 3 automatic color inversion tools, but I prefer to invert manually. No matter how I go about the inversion, I can't get that color to be even close (without destroying every other color in a photo). In case you're wondering, I have zero complaints about the colors I normally get, as long as it's not this one

This chart simplifies the complexity of the issue...you have to be able to go down the Yes side all the way to the bottom...if at any step the ansswer is 'No', you are subjected to the issue of NOT seeing a particular hue correctly!
Then, if shooting a digital image of a color negative, you also run into the issues of Invert of the negative to a positive, and the shortcomings of that step in the process, as well.

foc · Jul 30, 2023

I am just amazed that this thread has gone on for 123 posts.

DREW WILEY · Jul 30, 2023

Just let the Pope decide whether Magenta is a color or not. I think the college of Cardinals calls it crimson instead. But no print shop would mistake those two, nor would a Cardinal bird seeking a mate.

Sirius Glass · Jul 30, 2023

BrianShaw said:
If one puts aside their vindictive bitterness, one might realize that it is a passionate discussion with valid logic on both sides…

Magenta is not a single wavelength, but it can be produced by numerous combinations of multiple wavelengths. So if one defines a color as a single wavelength, then magenta does not fit that definition, but any color can be made with combinations of multiple wavelength.

pentaxuser · Jul 30, 2023

DREW WILEY said:
Just let the Pope decide whether Magenta is a color of not.

Why, is he the only person capable of such a decision?

pentaxuser

pentaxuser · Jul 30, 2023

foc said:
I am just amazed that this thread has gone on for 123 posts.

Only because you haven't been here long enough

pentaxuser

DREW WILEY · Jul 30, 2023

Why just the Pope? If you asked Henry VIII instead, you might end up in the Tower or worse, especially if you happened to be wearing the wrong color, mistaking it for magenta. He certainly got tired of Wolsey wearing it.

BrianShaw · Jul 30, 2023

Infallibility has its benefits, for both Popes and Kings!

Is it possible for a particular color to fall outside of the Portra 400 gamut?

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Is it possible for a particular color to fall outside of the Portra 400 gamut?

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