Blue-eyed Science

A few weeks ago, we talked about why the eyes of certain breeds like Siamese, Birman, Himalayan, and Tonkinese are blue. We showed cool diagrams and got to use nifty scientific terms and stuff. Mommy was in heaven. She's weird that way.

Today we're going to talk a bit about other things that can impact the way blue eyes look.

Sometimes people have asked if our photos are tweaked a bit. (Maxie's eyes can't be that blue in Real Life. Surely you "enhanced" it a bit, didn't you?)

The answer to that is yes...and no.

If you see what appears to be different eye colors from photo to photo, that can be due in part to something called the angle of incidence.

Cameras 2 & 3 positioned for holiday shoot
at singer/songwriter Jewel's ranch.

We see this a lot in my line of work:

Say we're on location. The set is beautifully lit, with three cameras ready to film, positioned in a circle around the subject. All three are looking at the exact same scene, and all three can be "seeing" that scene's colors differently.

The way the light hits the camera lens - and because what one camera sees in the background is different from what the other camera sees - it can make the shot look "off," color-wise. The cameras don't appear to match each other.

But how can this be if the cameras are the exact same make and model, and they are set at the exact same settings, with the exact same lenses? Remember Raleigh scattering that we discussed in our post on December 9?

Light bends, and it bounces. And because the cameras are in different positions, the angle of incidence of the light is different. And therefore the shot will look different.

So we have to color correct - or "shade" - the cameras before we roll.

Below is a perfect example of angle of incidence played out with Allie as the model.

These photos were taken one right after the other, but the camera was moved almost halfway around in position between shot 1 and shot 2. What a difference it made in her eye color!

This doesn't happen all that often with Allie. But with Faraday, and even more frequently with Maxwell, you'll see quite a bit of color shift. There's a lack of pigment to "anchor" the color, which means its appearance is more dependent upon those bouncy light rays.

Color temperature can also impact what you see. Take a look at these two photos of Faraday. In the first, it's an overcast day so the lighting is flat and the camera "sees" Faraday's eyes as more blue-green. In fact, the entire photo is more blue in tone.

In the second shot, he's inside on a sunny day, lit from the side. His eyes have more of a green cast to them.



Maxwell's eyes - perhaps because of the complete lack of pigment - tend to vary the most.

He was in a shadowed location for the above shots. In the shot below, he is lit entirely by direct sunlight. There is more scattering of blue light. (Additionally the shot is overexposed, leaving the entire photo looking washed out)

By the way, you can see the same phenomenon played out in the sky above you. You can have two completely cloudless days but one will have a much deeper "Colorado" blue sky than the other. Perhaps it has to do with air quality? More particles in the air (pollen, dust, etc) make for more scattering.

One last point: lighter eyes will much more easily reflect their environment. In the photo below, Faraday is surrounded by green leaves, and you can see that green reflected in his eyes. And in Maxwell's photo, the eye closest to the table is reflecting some of the golden tones of the wood back into his eye.

Again, none of these photos were retouched or color corrected.
This is how they look raw, straight from the camera.

So to answer the question occasionally posed, do I "bump up the saturation" in Maxwell's eyes? Sometimes. As all photographers will do, I color correct my photos before publishing, to "normalize" them. To make sure skin (ahem, fur) tones are correct and not too ruddy or blue. And to make sure eye tone isn't too "off" from the way they normally look.

And here's an example. That photo of Maxie above? Here it is, before and after color correction:

Okay, science/photography class is over. Time for a...

Holiday Extra

That camera shot above in Jewel's kitchen? Here's the final video - it's one in a series of 26 tips we filmed with Jewel, food blogger Jaden Hair and the star of "My Fair Wedding," David Tutera.
(Bonus: it's a pretty cool tip, too!)

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PetSafe FroliCat Giveaway!

There's still time to enter this very special giveaway - you'll be giving the gift of fun to a shelter pet in the process!

Just click this link here (or the badge to the left, either will get you there) to learn more.

Giveaway is open until 12/31.

Monday Medical: Blue-eyed cats

Last year, we did a series of Monday Medical articles on albinism in cats. Since Maxwell and Faraday are temperature-sensitive albinos, this was a fun and interesting topic for me to write about.

Temperature-sensitive albinism is what causes breeds like Siamese, Burmese, Himalayans and Tonkinese to have pointed coats - darker in the extremities and lighter in the torso. You can click here to read last summer's article about it.



But did you know this albinism extends to eye color, too?

There are two layers in the iris of the eye that determine what color your eyes are (both in humans and cats) – the stroma and the epithelium.

In most cats, pigmented cells are scattered throughout both layers. 

But for cats who have Siamese or Burmese alleles, (a gene pair that causes temperature-sensitive albinism) there is no pigmentation in the stroma.

And, whereas other cat breeds with blue eyes have pigment in that lower epithelial layer, the blue of a Siamese is due to the absence of pigment in both layers.


If there's no color in Maxwell's eyes, 
why do they appear blue?

For the same reason the sky is blue.

(here you go, moms! the answer to the age-old question kids everywhere ask.)

In really basic terms it has to do with the fact that, of all the colors in the visible light spectrum, blue has the shortest wavelength, and colors with shorter wavelengths scatter more than colors with longer wavelengths – it's called Rayleigh Scattering. Since blue light is the predominant light that is bouncing around in the stroma layer, that is the color you see (shown by the cool red arrows in the diagram above!).

Faraday, on the other hand, as a Tonkinese, does have a small amount of brown pigment in his epithelium layer. So all that blue light bouncing around in his stroma is impacted by the slightest of tints in that epithelium.

His eyes are technically classified as "aqua," though in my opinion, they often appear to be sea-green in color.

So there you have it, folks. Siamese cats: living out the answer to the age-old question of why the sky is blue.

Oh, and yeah. We think it's pretty cool that all this came about because the boyz are albinos!

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Sources:

Why the sky is blue: Science Made Simple
 
"Ocular pigmentation in white and Siamese cats", Invest Ophthalmol Vis Sci. 1980 May;19(5):475-86. Thibos LN, Levick WR, Morstyn R.

Comparative Opthalmology, Chapter 11, UC Davis School of Veterinary Medicine

Angle of Incidence explained