Human eye

How Does the “8x” Zoom on My Point-and-Shoot Compare to My DSLR?

Your camera may boast “8x zoom”, but most DSLRs do not advertise values like these. So how do they compare? The answer is more complex than you may think.

That “8x” value that doesn’t necessarily mean objects in the photo will look 8 times bigger than they do with your eyes. It just means things will be 8 times bigger than its most zoomed-out position—but two cameras in their most zoomed-out positions will not look the same size.

Every lens affects your image in a different way. A wide angle lens warps the perspective in the image so it shows more than you could see with your naked eye. A telephoto lens does the opposite, zooming in like a telescope to distant objects. These things are separate from the actual “zoom” function on your camera, so one 8x zoom lens may not make objects as large as another 8x zoom lens.

So how do we calculate how much bigger an object appears in a photo compared to your eyes, where you’re currently standing? To find that out, you need to know the focal length and field of view of the lens you’re using.

“Canon vs Nikon:”
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Focal Length and Field of View

In photography, the focal length of a lens is the distance between a the camera’s sensor and the internal components of the lens itself. This focal length determines how close objects look to your camera and what part of the scene actually fits within the picture—otherwise known as your field of view. A massive, telescope-like lens with a 1000mm focal length will make objects look very close. Lenses with smaller focal lengths will make objects appear farther away.

Many lenses can “zoom” to different focal lengths. For example, an 18-135mm lens will let you zoom from an 18mm focal length to a 135mm focal length.

Here’s an example. I shot the following two images with my Canon 650D and an 18-135mm lens.

The first photo was taken at the shortest focal length: 18mm. It’s a pretty wide field of view.

The next photo was taken in the exact same place half a second later. The only difference is that I’ve zoomed in to use the lens’ longest focal length, 135mm.

As you can see, the field of view is a lot narrower in the second photo than the first, because we’ve zoomed in on the mountains.

Here’s the catch, though. Different lenses, at their shortest focal length, will show things differently. Remember that 1000mm telescope lens? Even if you don’t zoom in with it, you’re still seeing things much closer than a camera with an 18-135mm lens. So focal length alone isn’t…

How To See Colors That Don’t Exist

by Alex Carter

The human eye can distinguish approximately 10 million colors. If you’re anything like us, you’re probably wondering where the other colors are. Is this it? Are we condemned to a life of boring blues and requisite reds? Will we groan at greens and yawn at yellows forever? Apparently not: turns out there are six colors that you can see that don’t exist.

Firstly, let’s get it out of the way … technically, magenta doesn’t exist. There’s no wavelength of light that corresponds to that particular color; it’s simply a construct of our brain of a color that is a combination of blue and red. But it gets stranger. We’re not just talking about that sort of thing—we’re talking about actual colors that you need to trick your brain into recalibrating itself in order to see.

Our eyes have receptors called cones for three different colors: red, green, and blue. By measuring the combined responses, secondary colors can be constructed. For example, a combination of red and green makes yellow.

However, if the eye reports the red and green receptors are being stimulated, the brain also processes the absence of blue. This is not only important for being able to interpret colors instantaneously, it also allows the brain to correct for different…

How to chill an object by sending its heat into space

solar panels
solar panels

When a refrigerator cools your food, it takes the heat away and dumps it into your kitchen. That adds to your home’s cooling bills. Likewise, when your air conditioner cools your home, it sends that heat outdoors. It also makes things warmer for everyone else in your neighborhood. The farther away you can send heat, the better. And there’s not much farther you can send it than outer space. Now, researchers have built a device to do just that. It cools down an object by radiating its heat directly into space.

For now, the device isn’t too practical. But its designers say that such cooling methods, combined with other techniques, might one day help people get rid of unwanted heat. The device would be especially well suited for arid regions, they add.

Radiation is the means by which electromagnetic waves carry energy from one place to another. This energy might be starlight traveling through space. Or it could be the heat of a campfire warming your hands.

The bigger the temperature difference between two objects, the quicker that heat energy can radiate between them. And not many things are colder than outer space, notes Zhen Chen. He’s a mechanical engineer at Stanford University in Palo Alto, Calif.

Outside of the envelope of gases surrounding Earth — our atmosphere — the average temperature of space is about –270° Celsius (–454° Fahrenheit). Chen and his team wondered if they could take advantage of this big temperature difference between Earth’s surface and outer space to cool an object on Earth, using radiation.

For an object on Earth to shed energy to space, radiation must travel through the atmosphere. The atmosphere doesn’t let all wavelengths of radiation through, Chen points out. But certain energy wavelengths can escape with little resistance.

One of the atmosphere’s clearest “windows” is for wavelengths between 8 and 13 micrometers. (At these wavelengths, electromagnetic radiation is invisible to the human eye. Because their energy is lower than that of red light, these wavelengths are called infrared.) Fortunately, says Chen, objects at about 27 °C (80.6 °F) radiate much of their energy in just that window.

Building a heat-emitting device

To study the new concept, Chen’s team built an object they would try to cool. They used mostly silicon. The basic ingredient in beach sand, silicon is both cheap and sturdy. It’s also the material computer chips are made from. That meant Chen’s team could use the same techniques used in making computer chips.

selective emitter
In a new cooling device, a shiny layer of aluminum (bright layer at bottom) and a coating of silicon nitride (top surface) help radiate heat from a layer of silicon (middle) into space.

The base of their object was a super-thin disk of silicon, about twice the thickness of a human hair. That layer was for structural support. To that, they added a thin layer of aluminum. It reflected light waves like the shiny layer on the back of a glass mirror. The aluminum layer would send the object’s heat upward, toward space.

Next, the researchers added the layer of material they wanted to cool. It, too, was made of silicon, but was much thinner than the base layer. It was just 700 nanometers — billionths of…

Did You Know Why Squinting Helps You See Better

Luke asks: Why when I squint does it help me see things clearer?


squint
Squinting causes two reactions that help you visualize the world around you in better detail. First, it changes the shape of our eye, allowing light to be focused better. Secondly, it decreases the amount of light that is allowed to enter the eye. Light coming from a limited number of directions allows that light to be more easily focused. 
If all that seems a bit vague, it is. To completely understand why these two reactions help us see better, let’s take a more in depth look at vision, light, and how the eye works. 
At its core, vision is just the perception of light by our brains. It’s important to note, the term “light” can refer to any electromagnetic radiation, not just the radiation in the visible spectrum. This radiation is a natural result of one of our four fundamental forces, electromagnetism. 
Electromagnetic radiation can be classified into seven types- Gamma, X-ray, Ultraviolet, Visible, Infrared, Microwave and Radio wave. Visible light actually comprises a very narrow range of frequencies that can be perceived by humans. This human-visible light has the same characteristics of all types of electromagnetic radiation. Namely, it comes in the form of frequencies. It’s these specific frequencies (wavelengths) that give our eyes the ability to perceive colors, as well as objects. Other frequencies allow us to see our bones through our skin, via X-rays (but that’s another topic altogether). 

How does this wonder of evolution, the eye, actually work? 
Our eyes have many different layers functioning together to trap light and turn it into an electrical impulse the brain can process. The outermost layer is called the sclera. This is the white part of the eye that gives it its shape, and where the muscles that control eye movement attach themselves. On the front part of the sclera is a transparent bit called the cornea. All light entering the eye must first go through the cornea. 
The next layer is called the choroid. This layer contains the numerous blood vessels that supply the many parts of the eye with nutrients. It also contains the iris (the colored portion of the eye) and ciliary muscles that control the lens of the eye. Together with the cornea, the lens helps refract all of the light that enters the eye and focus it on the innermost layer, the retina. 
The retina contains two different types of photoreceptors responsible for vision: rods and cones. When light strikes these cells, it reacts with visual pigments within them. These pigments contain a class of proteins called opsins. Together, with a molecule known as a chromophore (in humans this chormophore comes from vitamin A), light frequencies reacting with these pigments cause the electrical impulses your brain receives. 
In the human eye, there are four main types of opsins that react to different light wavelengths. Cones use three types and Rods use one. 
Rods far outnumber Cones in the human eye, approximately 120 million compared to just 6-7 million cones. They are much more sensitive to light than...