I think we are discussing different subjects in the same thread.
One subject is the observation of colour in real life, while the second is how we are able through our technique to intensifie or create a colour effect.
Painting a halo that is or is not there is a one of the many options we have that serve a purpose. For example, it is useful to unify the painting, it can help placing a subject IN a certain area by stressing its presence there, it can relate the subject to the background.
A red halo coming from a subject that is not red will alter the temperature of the subject's colour, perhaps turning it slightly toward coolness. I think instead that Sargent's reds are there to deepen the shadows through making them very hot.
Euan Uglow's painting (can't post them, I am referring to his nudes) are dotted with little red reference marks, and often red or orange outlines, that structure the drawing and add importance to the surface the painting, they also affect strongly the colour scheme.
I gave up cadmium red at the time of the famous thread, but found myself in the need of putting it back on the palette to have its power available!
Ilaria

Jean,
I used your photo and painted the sky with the dark from the upper right corner. Did not changed the color of the moon, only the halo is gone.

Allan

That's a lesson!
Ilaria

Your welcome Carol!

This particular halo was enormous, which is not shown very well by a small photo. It was brilliant white, and lasted about 20 minutes before fading rapidly. It was magical!

Allan, it's not nice to mess with Mother Nature!

;)

Jean

The difference is very interesting and dramatic. Thanks for the original photo, Jean. What a sight that must have been!

Hi Alex, yes it was breathaking. I had chills while trying to get the photo.

Since this thread was reborn, and seeing this example in real life I've been watching for signs of halos in reality. It is so easy to become complacent and miss these natural events. I'm so glad this thread was brought back up. I needed a kick in the you know what.

Jean

Jean,
I

For anyone brave enough to wade into some of what has just been euphemistically referred to as "famous threads" (which has more to do with vehemence than verisimilitude), the subject of "halation" has come up before.

At the very least, by searching for that word, you'll get to read a chapter from John Zeissig's archived but not forgotten "Once Upon a Time in the West."

There's a fair bit of chaff back there with the oats, so take a bandana and a shovel.

My point exactly, Allan. The reflected light or "glow" is really there. The posterization is really interesting, the quailty of the light changes all the way through it's ring. There is another "wolf" moon forming outside right now, it's very faint and only 3/4ths formed. So anyone on the forum right now, run outside and take a peek. That is, if you are in the northern hemispere of the Americas. :thumbsup:

Jean

Steven,

Thank you for the AhhA!! moment. Although I've departed from Portraiture for now, the Optical Red technique applies.

This past weekend my daughter was visiting from Berkeley for a much needed rest. I'd been working on a large banana still life, (trust me it's cool) and while she watched, I applied a deep red into the negative space around the highlight / leading edges. The effect was to "lift" the subject right off the canvas, In her words, Vibrant!!!

Once again, I'm transformed from idiot to savant, at least in her eyes.

I've said this before, but it's worth saying again, to those who may be thinking about joining this forum.

I returned to painting after a 20 year break. Trying to get up to speed, I spent the first few years pouring over posts on all manner of web sites offering artists a voice. After much wasting of time, I've narrowed my list of favorites to this one, only.