Q. for the experts. Why is it so hard to capture green flashes on a diamond?

[Dancing Fire]

Red and blue flashes is much easier, but capturing green flashes is next to impossible. This is the only photo I have with a green flash. Do you have any pics of green flashes to share?

 

[blueMA]

Here you go. Green bomb!

 

[stracci2000]

 

[kal2021]

 

[SimoneDi]

It is easier to capture it if you take a live photo.

 

[yssie]

I’ve read some interesting articles on this. Here are some of the best, IMO:

How we see colour biologically:
https://www.handprint.com/HP/WCL/color19.html

Optical phenomena in diamonds:
http://www.gemology.ru/cut/english/rainbow/3.htm
https://www.pricescope.com/articles/fractioning_color_gem

A very long, very old thread with fantastic discussion (and some fantastically cringe-worthy commentary so don your filters):
https://www.pricescope.com/community/threads/fire-and-dispersion-techy-help-please.18987/

The very short version of the above:
1. A “light ray” isn’t two-dimensional.
2. The wider the dispersion fan, and the smaller the pupil, the more intensely all colors of the visible spectrum will be observed. The wider the pupil, the less likely it is to see green in particular.

Copying quotes from that PS thread to explain these somewhat cryptic pictures (from the article linked above):

The wavy lines indicated the width of spectrum band you can see. When you can see only 20nm, then all colors are saturated – you can see each one distinctly. As the width that you can see increases to 150 nm, the saturation of red and blue is still 100% (but faint) - and you will see them distinctly at their respective ends of the spectrum, but green is reduced to 40% if you see only 150nm wide in the middle of the spectrum. When the width you see reaches 200nm (half of the visible spectrum), then none of the green is visible.

As gems are usually viewed in good illumination conditions and from convenient distances, the pupil diameter can be assumed 3mm and the distance to the gem being 25cm, in which case the pupil angular size will be 0.7°. In this case, to see only a wavelength interval of 50nm (to see pure colors) requires angular dispersion from the gem of at least 14°/nm. Angular dispersion less than 3.5° leads to complete loss of green, and the other colors being seen rather rarely. It should be emphasized that fire improves with increasing distance between the gem and the observer, but diminishes at lower illumination, which makes the pupil expand.

The above is true only if the prism is illuminated with a single light wave, as generated by a point source or one at a distance much greater than its size; in other words, one of small angular size to the gem. For an expanded source of illumination, the rays emitted from its different points, thus entering the prism from different directions, would mix their colors on the retina, degrading the purity of color. Hence, good fire also requires illumination of the gem from a light source of small angular size, as well as small angular size of the observer’s eye pupil.

Since the angular size of the sun, a lamp(?), or a candle does not exceed 0.5°, the fire depends primarily on the pupil angular size. The fire of colorless gems is perfect in sunlight and even better in illumination coming from multiple point sources ... then there will be as many color fans from the gem as there are light sources. The fire from a faceted gem will be completely lost in the light of a dull day under a cloudy sky.

But your question refers to a camera “seeing” green, not the human eye, and that adds a variable that isn’t accounted for in any of the above. I am confident details about lens and processor are critical, but I don’t know nearly enough about cameras to know what questions to ask. Hopefully someone who does know cameras will see this thread and can comment.

 

[cflutist]

DF,

Here are some green from my CBI diamonds

 

[John P]

Adding to the above -

A spectral fan, put out by a diamond, is a physical rainbow of colors with ends and a middle.

The ends of that fan are red and violet.
Green is toward the center, where yellow and blue intersect.



If a spectral fan is large enough at your eye that only one color enters your pupil you see a flash of that color.


If the spectral fan is small and enters your pupil all at once you see a flash of white.



The lens aperture of a camera works similarly. The trick with green is that it occurs in the middle of the dispersed spectrum.

Here are images of an excited little diamond's spectral-fans, projected to the walls of an airplane. Look at the images, especially at upper-right, and notice how green is elusively positioned between yellow and blue. Generally speaking, the bookend colors are easier to capture in casual diamond photography.

 

[Bron357]

Woo hoo me too
I like the purple!

 

[blueMA]

Woo hoo me too
I like the purple!

wow, you created your own rainbow there!

 

[Austina]

 

[Dancing Fire]

DF,

Here are some green from my CBI diamonds

Cf
Beautiful shots!

 

[Karl_K]

Also digital cameras do a very poor job of photographing green turning it blue, even with having more green sensors in an attempt to match the human eye.
Take a photo of grass on a bright day than laugh at how badly it displays the green color in the photo.
It is maddening when you see a landscape with stunning greens and take a photo and it looks total blah even with a high end camera.
Same with taking a photo of green fire and it comes out bluish.

 

[MarionC]

 

[the_mother_thing]

I managed to capture a quick/small green flash today in my OEC (using iPhone XR). **sorry this posts Hell & huge.


And one I had from my MRB a little while ago.

 

[yssie]

Also digital cameras do a very poor job of photographing green turning it blue, even with having more green sensors in an attempt to match the human eye.
Take a photo of grass on a bright day than laugh at how badly it displays the green color in the photo.
It is maddening when you see a landscape with stunning greens and take a photo and it looks total blah even with a high end camera.
Same with taking a photo of green fire and it comes out bluish.

...I’m a cult Canon fan. No one - no one - makes skin glow like Canon. I take my G7X everywhere. I swear, if my skin actually looked the way this camera sees it...

Neither of my Canons (G3, G7) do landscapes phenomenally well - for scenery shots where I don’t mind a cooler cast and blown out colour I’ll pull out the Nikon (D3400). It resolves greens in particular very nicely - to my eyes, anyway.

I don’t particularly ever want to use the Nikon, mind, but it’s one way to take some of the sting out of having bought the thing. Even perfectly wb people of all races come out of it looking like they’ve got Casper somewhere in their ancestry

 

[blueMA]

I have very costly professional Canon DSLR full frame cameras along with the highest qualty L Canon lenses money can buy. Although the HDR function and various program modes work quite well and helpful nowadays, NOTHING can copy what you can see with your own eye, especially for true colors and true value (contrast and grey scale).

 

[junebug17]

Here's a little green from my band -