Why Do We Get Red Eye in Photos?

iStock/Liia Galimzianova
iStock/Liia Galimzianova

Grab a partner and look into his or her eye "“ or stare deeply into it, if appropriate "“ in a normally lit room. The quick and dirty version of how you're able to view each other is this: Light enters the eye through the cornea, the clear outer dome, and goes through the pupil. Then it travels to the cornea, which focuses it on the lens. The lens further focuses the light and spreads it across the retina. The retina receives the light and transmits signals via the optic nerve to the brain, which interprets the image.

As light enters the eye, some of gets reflected back, but the amount of light in most situations is so small, you wouldn't even know it. Right now, your partner's pupils look black and everything's normal. Now grab a camera and take a picture of your partner with the flash on. There's that demonic red eye.

Here's what happened: When you took the picture, the camera flash sent a lot of light into the eye in a very short time, the light reflected off the back of the eye and out through the pupil and, because the camera lens is close to the flash and able to capture images very quickly, it caught the light reflecting back out.

Seeing Red
So why is that light red?

Because the fundus, the interior surface of the eye that includes the retina, is loaded with melanin, a pigment that gives it a brownish-reddish color. Was that anti-climactic? Sorry.

Red eye is fairly easy to curb by using the "red eye reduction" setting found on most digital camera flashes. This setting causes the flash to go off once before the picture is taken, which causes the subject's pupils to contract and let less light in and out, and then another time to take the picture. Cameras with a flash farther away from the lens also reduce red eye because the flash hits the subject at a different angle than lens captures it.

Of course, red eye isn't all bad. The same mechanics of light reflection that ruin photos also allow doctors a non-invasive way to see inside the eye. Hermann von Helmholtz, a German physician, discovered in the 19th century that he could examine the retina by holding a bright light near his eye and shining it into patients' pupils.

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This Course Will Teach You How to Play Guitar Like a Pro for $29

BartekSzewczyk/iStock via Getty Images
BartekSzewczyk/iStock via Getty Images

Be honest: You’ve watched a YouTube video or two in an attempt to learn how to play a song on the guitar. Whether it was through tabs or simply copying whatever you saw on the screen, the fun always ends when friends start throwing out requests for songs you have no idea how to play. So how about you actually learn how to play guitar for real this time?

It’s now possible to learn guitar from home with the Ultimate Beginner to Expert Guitar Lessons Bundle, which is currently on sale for $29. Grab that Gibson, Fender, or whatever you have handy, and learn to strum rhythms from scratch.

The strumming course will teach you how to count beats and rests to turn your hands and fingers into the perfect accompaniment for your own voice or other musicians. Then, you can take things a step further and learn advanced jamming and soloing to riff anytime, anywhere. This course will teach you to improvise across various chords and progressions so you can jump into any jam with something original. You’ll also have the chance to dive deep into the major guitar genres of bluegrass, blues, and jazz. Lessons in jam etiquette, genre history, and how to read music will separate you from a novice player.

This bundle also includes courses in ear training so you can properly identify any relative note, interval, or pitch. That way, you can play along with any song when it comes on, or even understand how to modify it into the key you’d prefer. And when the time comes to perform, be prepared with skilled hammer-ons, pull-offs, slides, bends, trills, vibrato, and fret-tapping. Not only will you learn the basic foundations of guitar, you’ll ultimately be able to develop your own style with the help of these lessons.

The Ultimate Beginner to Expert Guitar Lessons Bundle is discounted for a limited time. Act on this $29 offer now to work on those fingertip calluses and play like a pro.

 

The Ultimate Beginner to Expert Guitar Lessons Bundle - $29

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Why Did Noon Used to Mean 3 p.m.?

3 p.m. is basically noon for people who wake up at 12 p.m.
3 p.m. is basically noon for people who wake up at 12 p.m.
Mckyartstudio/iStock via Getty Images

If you’re a late sleeper, you might find yourself thinking 12 p.m. seems way too early to be considered midday, and the word noon would much better describe, say, 3 p.m. It turns out that ancient Romans would have agreed with you, if only for etymological reasons.

As Reader’s Digest explains, the days in ancient Rome were split into four periods of three hours each. The first hour was at sunrise around 6 a.m.—called prime, for first—followed by 9 a.m. (terce, denoting the third hour), 12 p.m. (sext, for sixth), and 3 p.m. (none, for ninth).

According to Merriam-Webster, Middle and Old English borrowed the time-keeping tradition, along with the Latin word for ninth, which was changed to nōn and eventually noon. Though we’re not sure exactly when or why noon started referring to 12 p.m. instead of 3 p.m., it could have something to do with Christian prayer traditions. In the Bible, Jesus’s crucifixion is said to have taken place at the ninth hour, and that’s when worshippers partook in their second of three daily prayers; the others were in the morning and evening. It’s possible that hungry monks were behind noon’s gradual shift from 3 p.m. to 12 p.m.—since their daily fast didn’t end until after the midday prayer, they had a built-in motive for moving it earlier.

While we didn’t exactly stay true to the original Latin meaning of noon, there’s another important remnant of ancient Rome hiding in the way we tell time today. Romans referred to 12 p.m. as meridiem, for midday, and so do we. A.M. is an abbreviation for ante meridiem, or before midday, and P.M. means post meridiem, or after midday.

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