#light inversion

[morgansram]

Light inversion on various shells (Cretean Snail/ Mediterranean Snail/ Nautilus)

Photo: Julian Köpke

[90sfantasyanimestuff]

Slayers, Lina art by Rui Araizumi

[knockknockwhosthereartistism]

Some cards to give to your loved or hated ones this Valentines Day!

Bonus Billford:

[kacievvbbbb]

God again I’m just so obsessed with how far this family has come and how with every chapter they just behave more and more like a family and less what a family should be like.

Like a couple chapters ago Yor was still calling her Miss Anya and now that’s her mom. She would have never jokingly “lied” to her before and would have even freaked out at the mere question there was something less than normal about her. But here she is your honor this is a family.

My favorite thing about spy x family has always been how consistently Yor has Anya’s back no matter what shit she gets into Anya akways stands ten toes down because she knows Yor is always rocking for her. I think a lot about how the way Loid chose to comfort Yor and reassure her abilities as a mother is by telling her that she makes Anya brave because she know Yor will always, always protect her and just what else is a parent than someone that makes you brave?

It’s even more poignant to come in a chapter where we are introduced to Anya’s birth mother for the first time and there’s definitely the similarity being drawn. Yor loves Anya would give everything up for her but would also do anything to make the world safe for her. When Yor felt there was no reason to go on with her spy work she thought of the little family she’s made for herself, of the little troublesome girl she’d risk it all for and she just knew that there were still people worth making the world safe for.

God I love this family

[sirfrogsworth]

Understanding the Inverse Square Law

(Without Math)

When I was first getting deep into photography, I kept running into lessons about the inverse square law. They would always tell you the effects and the math but they never explained the cause. Why does the light do this?

It's like when the doctor gives you a pill to fix something. You swallow it, wait a bit, and eventually you feel better. But you rarely know what the pill is actually doing.

So when it comes to lighting, you have to decide if you want to be the doctor who understands the why or the patient who just swallows the pill and gets the desired effect.

Every tutorial will say if you double the distance of a light from a subject, the intensity will drop by 1/4. They will give you a formula so you can do exposure calculations.

Sometimes they will refer to somewhat helpful diagrams with clues on what is happening.

But most just teach the easy version.

If you move the light closer, you will get quicker falloff into shadow and the background will be darker.

If you move it farther back, everything will be more evenly lit, but the background will be lighter.

The teacher will shoot some examples and show you something like this.

By the end of this post, I want everyone who reads it to *truly* understand what is happening.

Because if you understand it on that level, it will change how you think about light and photography. It will have the added bonus of explaining magnets and WiFi and even the sound coming out of your speakers.

If I am an effective teacher, this is something you will think about in your everyday life, even if you don't care about photography.

In a previous post, I talked about how light was a bit like a shotgun blast. The closer you are, the more concentrated the pellets. If you are farther away, the shot disperses.

But this wasn't the analogy I wanted to use. It was just the easiest to find visual examples of.

My preferred analogy was spray paint. And I'm hoping with some janky home-made visuals, I can do a better job of explaining the concept.

Let's start by explaining the humble photon. It's the fundamental particle (or wave) of light. Think of them like individual tiny globs of paint in a spray can. A photon is emitted when something loses energy. And unmodified light sources typically shoot out photon globs in all directions.

A point light source is a theoretical concept where a single point in space shoots light evenly in every direction. For our purposes we're just going to imagine a basic light bulb as the point source.

But our eyes and cameras have a limited field of view, so from here on out we are going to think of the light emitting from the bulb as having a cone shape. We are just concerned with what a camera can actually see.

Well, well, well... what does that cone of light look like?

I'm sure we have all used spray paint before. So let's imagine we are spraying a white ball against a gray wall. We spray for 1 second and hold the can at different distances.

In each scenario we are spraying for the same length of time and the exact same number of photon paint globs are emitted from the nozzle.

Let's think about what each scenario would look like from the camera's point of view.

Here is our unpainted ball and wall.

Here is the spray can held at Distance 1.

Note how the red paint is very concentrated and appears bold and saturated.

Distance 2.

Now the same amount of paint is dispersed over a wider area. The bold red spot in the center is more muted. And some of the paint is spilling onto the background.

Distance 3.

Everything appears to have a light red tint. The background and the white ball appear to have similar intensities of red. The coverage is very even. The same number of photon paint globs are being asked to cover a larger area so they are spreading out and diluting the color.

Okay, now let's exchange tiny photon paint globs for real photons.

I'm bringing back my baseball and showing these same 3 distances.

The nice thing about eyeballs and cameras... they can compensate for different light intensities. Our eyes have night vision and cameras have long shutter speeds, large lens apertures, and ISO amplification.

And if we compensate for the dimming caused by the dispersed light...

Photography teachers will tell you that if you move the light farther away, the background will get brighter. In reality, everything is the same level of dim and the camera exposure is brightened.

What if we wanted to spray the same area from far away without losing as much of the red saturation? We could add a super nozzle to our spray can that emits a bunch more photon globs in the same span of time.

This would be like turning up the power of the light. You have to emit a bunch more photons in that same time scale to compensate. Then you don't have to adjust your camera settings when you move the light farther away.

Let's look at a practical example of when you might think about the inverse square law to help solve a problem.

You have two subjects in a scene, and you put the light just out of view of the camera. You might be thinking that a larger light source is softer, so you want it as close as possible.

Unfortunately only one person is lit in the scene. She is getting the concentrated photons before they can disperse.

So if we want both people to have similar lighting, we can move the light farther away. You will have to comprimise a little softness. And you will have to change your camera settings or increase the power of the light.

Note that the intensity of light in the area they are standing in is very similar now.

By using a large light modifier, the photographer was able to move the light back and keep its general softness, but also evenly light both subjects.

And now I need to talk about one aspect of my spray paint analogy that does not work with the inverse square law. And it has to do with the specular highlight on the baseball.

Spray paint does not reflect paint. It just sticks to things. And reflection throws a tiny wrench into my explanation. Because parallel light rays do not obey the inverse square law. When you light something, the most central photons from the subject's perspective are going to be traveling in parallel. They have a direct path from the light to the camera lens or your eyeball.

Now if the reflection material is perfectly matte, the light will disperse and act as the inverse square law suggests. But if the surface is even a little glossy, the most concentrated parallel rays are going to bounce directly into your eye as a bright white spot.

And if you study this diagram a little closer, you might figure out why specular highlights are usually white.

If you look at the specular highlight on the baseball, even though the rest of the image gets dimmer as the light gets farther away, that spot stays bright.

Though the spot seems to disappear at Distance 1. Curious, eh?

It's still there. It's still reflecting directly into your eyeball. But the light around it is so concentrated and bright, the specular highlight blends in.

Which means if you have some nasty highlights on your photo subject, moving your light closer might make them go away. If someone has a shiny forehead, this can equalize the overall exposure and hide the shiny.

This guy has a bright spot on his nose. It is there in both photos.

But his face is so much brighter in the left photo that the spot blends in. It's a bit of a mind bender because the camera exposure is adjusted so the finished photos appear the same amount of bright.

You have to remember if you only move the light farther away and don't increase its power or increase the camera's exposure level, the photos would look more like this.

So if you make the rest of the face as bright as the highlight, it blends in.

Neat!

So, was I successful?

Does the inverse square law make more sense?

This is why WiFi gets weaker at a distance. This is why magnets lose their attraction when you pull them apart. This is why speakers get quieter when you move away from them.

I can't tell you how much knowing the why has affected my thinking about lighting. I see so many video and photo people talking about lighting setups who are just following memorized placements.

"Put a light above the subject at a 45 degree angle to get Rembrandt lighting."

But the second they encounter light doing something unexpected, things fall apart. They resort to trial and error and brute force the solution.

Knowing how the pill works can prevent that frustrating process.

I no longer care about the math. I can just visualize the cone of influence and predict what will happen. Understanding the behavior of light and not just the end effects has made everything more intuitive. I just wish it hadn't taken me so long to understand this. But, hopefully, this post has shortened that journey for you.

[fluffylord]

TWELFTH DOCTOR I THE ZYGON INVERSION

[xellos-room]

Lina and Xellos from the light novel Slayers volume 16

[poedays]

As Lovely died, they took the light with them.

When Lovely was faced with the shade, everything in them tensed.

Their core trembled in their chest, their mind, in their very being. As they were drained of life they thought of their power, their winning act in the games, their love, their life. The energy they possessed, the utter amplitude of what they beheld in their being. The strength being pulled from them.

And as they were dropped to the ground, all the bulbs burst in Vincent and Lovely’s house. Every light Lovely had used to practise their powers when they were first awoken. The lights Vincent caught them messing with when they couldn’t sleep. The lights they had felt comforted by in times of darkness. Every single bulb smashed.

As the pure energy they beheld fizzled out, so did the light that they had become attuned to. Their death was as unnatural as an eclipse. Fully natural at that. Not long lasting. But for that moment - that indescribable moment - the light had been taken from the world.

From their world.

From their core.

The light would never be the same again after that night.

New bulbs could be placed, but the lights would never shine the same way ever again.

[chibiaichan]

Slayers exchange!

[robotsafari]

“I’ve been alone so long that having someone else around is a little… overwhelming.”

HAPPY FATHER’S DAY TO MY FAVORITE INVERSE DUO MOMENT

[brainrotcharacters]

Darlin is the darkest black furred wolf in the pack and it's giving stealth advantage

[90sfantasyanimestuff]

slayers light novel cover

[ravenloftbythelamplight]

Here's the full, combined version of the Irik art from this post with both variants.

[czaneavecg]

tis why I dont do line art

hella messy as hell

[brolyng]

The Slayers