*Where* does sunlight scattering occur?

[agentredlum]

I guess the only way to settle this is to ask an astronaut. Are there any astronauts out there? What color is the sun from space?

 

[sophiecentaur]

That is exactly what I am saying, yes.

They auto correct colour to make for a good picture, based on what camera manufacturers deem "a good picture" under average circumstances for average users. (Having studied it in college and 10+ years in the photo industry, I could go on at length about white balances and neutral greys. De-correcting for auto-colour correction was a large part of my work.)

My little point-n-shoot has at least six settings to correct for colour temp. of lighting. It's default state is auto-correct. More sophisticated cameras have more sophisticated algorithms for correcting.

Unfortunately, what you want is exactly the opposite. You want a system that does no correction at all.

Without calibration, cameras cannot be used to compare colours like you are trying to do.

Your next range of cameras can shoot in RAW, which produces larger files but allows you to get the colour balance better by picking on a portion of the picture, or in the batch, with a reliable grey.

But we are verging on the subject of what colour 'actually is'. I have to insist it's totally in the mind of the viewer but that we can measure spectrum and equivalent 'black body' temperature very accurately. Colourimetry is based solely on a consensus of subjective opinions about colour matching of different combinations of differently produced primaries.

I was thinking that the thread was simply about the relative amounts of scattering of light from different directions and with the sun in different positions. Even though the measurements are a bit flawed, the results from my camera do show what I am getting at- and that is that there are places in the sky where you might expect R, G and B signals to be much closer to equal than in other places and that nowhere will the colours you see be very pure.
Get those tickets booked and tell us about it.

 

[sophiecentaur]

Have you ever made a pinhole camera?
I have, and i have looked through it.
Do your own eyes have correcting algorithms?

Yes they do. They are constantly correcting for the effects of the lighting on the colours of objects. If they didn't, you would see the same object at midday and at sunset and think it was a different object, because it would appear to be to different colours. The agenda they are following is not one of scientific measurement but of making the best sense of what they see of the world around.
Why should a pinhole camera make any difference to what colours you see, compared with just looking directly at a scene?

btw I saw that picture of the sun ("7)") - not sure what it was supposed to prove, though. The three 'representative' coloured objects were obviously there for some sort of reference. However, because the chromaticity values for those references weren't quoted (or even the values for the sun's surface, then the picture is no accurate evidence of anything.

The fact that the atmosphere makes a difference to the spectrum of the sun's light is very obvious, no?

 

[DaveC426913]

Have you ever made a pinhole camera?
I have, and i have looked through it.
Do your own eyes have correcting algorithms?

As sophie pointed out, absolutely. (Your brain that is.) In fact, our personal perception is far more heavy-handed at auto-correction than cameras.

Look around you right now. What lighting condition are you in? Tungsten? Fluorescent? Daylight? Did you actually have to think about it? Regardless of what it is, you will see it as white.

A camera (even with its auto-correcting feature) sees the difference between daylight and fluorescent so powerfully that you'll think your pix are ruined.

 

[sophiecentaur]

As sophie pointed out, absolutely. (Your brain that is.) In fact, our personal perception is far more heavy-handed at auto-correction than cameras.

Look around you right now. What lighting condition are you in? Tungsten? Fluorescent? Daylight? Did you actually have to think about it? Regardless of what it is, you will see it as white.

A camera (even with its auto-correcting feature) sees the difference between daylight and fluorescent so powerfully that you'll think your pix are ruined.

One man's "heavy handed" is another man's survival fitness. Homo sapiens, way back, was far more interested in recognising, consistently, the reflected colours of meat, mates and foliage than in assessing the colour of the Sun. We still have to take the jumper outside into the street to see just how near it matches the socks, though, when we're in Marks'.

 

[DaveC426913]

One man's "heavy handed" is another man's survival fitness. Homo sapiens, way back, was far more interested in recognising, consistently, the reflected colours of meat, mates and foliage than in assessing the colour of the Sun. We still have to take the jumper outside into the street to see just how near it matches the socks, though, when we're in Marks'.

Absolutely. Which is why I was originally talking about average use of average users. For most pedestrian intents and purposes, it's not a problem. It is heavy-handed because it's meant to be contextual. Trying to spot a tiger in the grass should not be confounded by the red of sunset versus the white of noon.But now we're into comparing colours of things in lighting conditions that are nowhere near average, and trying to pretend there's some calibration of absolute colour. No way.