man & nature # 81 ~ what color is a night sky?

Letting the dogs in under a full moon • click to embiggenI'm still messing around with this night picture making thing and it seems that my nightly ritual with the dogs keeps bringing back to this scene albeit an ever changing view.

One thing that I have discovered after messing about a bit with the white balance settings is that the color of the sky is (duh) determined by the WB setting. In particular, that often hyper-saturated blue color is the result of a WB setting that tends towards the 3200K temperature setting. A setting that usually renders the colors of "artificial" light encountered in the night in reasonable fashion - not "accurate" but not out-of-balance exaggerated either.

In fact, this scene, when pictured using a WB that essentially resulted in the color rendition that you see here in all but the sky, caused the sky to render as a hyper hyper-saturated blue that, to my eye and sensibilities, was way over the top. The most accurate color rendition of the sky, which is pretty damn close to what you see here, was achieved using a daylight (5200K) WB.

So, I blended the 5200K sky with the (approximately) 3200K (with a bit of localized tinkering) earth-bound features to achieve the final image that you see above.

And, I should note that the tonal balance between the sky and the earth-bound stuff is very close to what actually existed. Also, there is no detail in the moon because it was obscured by a small cloud which created a soft featureless disk kind of look.

As mentioned, I admit to being a night picture-making "novice". I really don't know what the "standard" WB is for picturing after dark although I am certain that it can vary considerably depending upon the predominant artificial light source(s) in any given scene. However, it seems certain that dependent upon any given WB (other than 5200K) is the hue of the color blue that the sky will be rendered.

All of which tends to lead me to want to have neutral night skies in my after dark pictures rather than ever-changing blue ones (although, deep blue-black skies are OK). After all, it's the black of the night, not the blue of the night that I see every night.

How about it? Any of you Nocturnes out there care to comment?

Comments

[Mauro Thon Giudici]

I am not a specialist in night photography. But from the physiology of the eye that I studied a long time ago in the dark we, humans, are far less able to tell apart the colors.

Color is however subjective, so I have made a fast search in the ancient literature about the way in which the night colors where supposed to be rendered.

The only reference I have found in 15 minutes is one from the usual Leonardo Da Vinci who has come to some conclusions very similar to yours. I will do some more extensive searches tomorrow.

Here is the piece (consider that you must make some interpretation):

"604.

OF THE WAY TO REPRESENT A NIGHT [SCENE].

That which is entirely bereft of light is all darkness; given a
night under these conditions and that you want to represent a night
scene,--arrange that there shall be a great fire, then the objects
which are nearest to this fire will be most tinged with its colour;
for those objects which are nearest to a coloured light participate
most in its nature; as therefore you give the fire a red colour, you
must make all the objects illuminated by it ruddy; while those which
are farther from the fire are more tinted by the black hue of night.
The figures which are seen against the fire look dark in the glare
of the firelight because that side of the objects which you see is
tinged by the darkness of the night and not by the fire; and those
who stand at the side are half dark and half red; while those who
are visible beyond the edges of the flame will be fully lighted by
the ruddy glow against a black background. As to their gestures,
make those which are near it screen themselves with their hands and
cloaks as a defence against the intense heat, and with their faces
turned away as if about to retire. Of those farther off represent
several as raising their hands to screen their eyes, hurt by the
intolerable glare."

The text is from here:

http://www.gutenberg.org/etext/5000

There also may be the possibility that the dark blue gained the status of norm for reasons of hue contrast against the yellow of the stars (another convention).

Anyway i find the image perceptually right in its colors (interesting is the little blue hue you left in some parts as a byproduct of postprocessing).

A totally different consideration may be made upon the photographic color, or the one resulting from the chosen sensible support as you pointed out.

[Joe Reifer]

With mixed streetlights and moonlight, a typical starting point is anywhere from 3000-4000K depending on the sources and how they mix. Many of my favorite color night photographs from the 80's-90's were shot on tungsten slide film (2850K). This work established a certain cool blue tonal look for night skies that has stuck with me in the digital age. See Steve Harper's website for some excellent examples: http://www.steveharperphotography.com/

Camera setup note: I leave my custom WB set to 3500K for night photography. While you can adjust the WB later in your RAW converter, it's helpful to have the feedback on the LCD screen be close to your typical vision of how a night sky should look.

Lastly, and most importantly, this is a beautiful image that is dense with texture, light and shadow!

Cheers,

Joe

[stephen]

This strikes me as one of those, "Well, d'uh!" moments. It certainly was for me. Moonlight is, after all, just reflected sunlight. Sunlight, of course, is somewhere in the region of 5,200K (higher, I imagine). And starlight certainly isn't going to be much lower (given that the sun is fairly cool, as stars go). So the fact that a WB setting of 5,200K produced the most natural-looking sky shouldn't really come as a surprise. Despite the fact that it does.

[Joe Reifer]

Daylight balance can work pretty well when there's only moonlight. When you've got clouds in the sky and city lights below, you've got mixed sources. Mark's solution to make 2 RAW conversions and blend with a mask in Photshop is a necessary tactic with some lighting combinations.

Adding your own light to the mix can make things even more fun. Here's a photo with a combination of 3 light sources, full moon, sodium vapor streetlights, and flashlight. One RAW file adjusted in Lightroom, around 3850K WB.

[Tim Baskerville]

As any visitor to The Nocturnes Web site - www.thenocturnes.com - can figure out, I'm a bit partial to the "sky is blue" school (having cut my teeth in NPy in the 80s and 90s,with afore-mentioned Steve Harper as a mentor) with a few notable exceptions.

Yeah, this discussion has pointed out that the moon is reflected sunlight (and for that matter, to photograph a full moon, on a clear night, then the "sunny-16" rule would apply, but that's a different discussion - i.e. astrophotography/heavenly bodies. But that (full moon-illuminated NPy) is a small part of Nocturnal Photography. More often than not, practicing Nocturnists are faced with images including the human-made environment, mixed lighting, and worse! Back in the 'film era' Nocturnes could count on Tungsten-balanced films to render the weird light sources they encountered on the streets (and in the overcast skies which refletced not-so-much moonlight, but the ground level ambient light, for instance) to render these colorations as somewhat neutral. This practice lives on today, with digital NPrs many times setting WBs as low as 2800-2900K.

In looking at the 'backyard nocturnes' in your posts (both stunning, BTW!), Mark - I can see the EXCEPTION to that blanket color philosophy and why you chose the path you took. Warm tones in the backyard tool area/fence in your first post seem very appropo. And, in the later post, where the sky (clouds, actually) are illuminated BY THE MOON - you are right -it's more towrad daylight. Now, imagine those same clouds, on a moon-less night (or one where moon was completely shrouded), illuminated by the ground-level light (more than you would think at first blush) - the WB/exposure would be much different.

The more I do this stuff (and see the proliferation of digital NPs), I see that it's effectively done on a case-by-case basis.

For another take on the color of the night sky - see award winner Tram Davies' entry in an online show we did - The Color of Night - http://www.thenocturnes.com/exhibits/colorofnight/awards.htm