YouTube / Brusspup
YouTube / Brusspup

Visual Trickery: Loopy Water, Unmoving Hose

YouTube / Brusspup
YouTube / Brusspup

This is nuts. In the two-minute video below, YouTube user Brusspup shows us how a carefully tuned speaker, a tube spitting water, and a camera can create an impressive optical illusion -- the illusion that water flows out of a seemingly unmoving tube in 3D spiral shapes.

So how does this work? It's actually pretty simple to set up: the speaker plays a 24 Hz tone (a very low note), which means 24 cycles of the speaker cone per second. A hose carrying water is attached to the front of the speaker, so it moves in time with the tone (thus, it is waving back and forth 24 times a second). This movement causes the hose to spray water back and forth. Finally, a camera running at 24 fps (frames per second) is pointed at the hose's output. The result is what you see below -- when we synchronize the camera's snapshots of reality and the speaker's movement, we see what looks like an unmoving hose -- the camera happens to snap a frame at moments when the tube is in the same place, so its wild movement is hidden. (Then Brusspup shows us the effects of tuning the speaker at slightly different frequencies -- trippy stuff, and you can now see the tube moving.)

What we're really seeing is a series of snapshots of water that happens to look really neat; the naked eye doesn't see this effect because the eye isn't a video camera (it is not limited to a "24 frames per second" view of the world). This effect is related to the reason that car wheels sometimes "go in reverse" when seen on TV or film: because the frame rate of any camera is limited, the motion of an object being filmed can interact with the camera in interesting ways.

With all that mumbo-jumbo out of the way, just look at this:

If you like that, you'll probably dig Strobe Lights & Water Drops, including a "Time Foundation" -- a technique using a strobe light to make water drops appear to "freeze" in mid-air.

(Via Colossal.)

Harry Trimble
Delightful Photo Series Celebrates Britain’s Municipal Trash Cans
Harry Trimble
Harry Trimble

Not all trash cans are alike. In the UK, few know this better than Harry Trimble, the brains behind #govbins, a photo project that aims to catalog all the trash can designs used by local governments across Britain.

Trimble, a 29-year-old designer based in South London, began the series in 2016, when he noticed the variation in trash can design across the cities he visited in the UK. While most bins are similar sizes and shapes, cities make trash cans their own with unique graphics and unusual colors. He started to photograph the cans he happened to see day-to-day, but the project soon morphed beyond that. Now, he tries to photograph at least one new bin a week.

A bright blue trash can reads ‘Knowsley Council: Recycle for Knowsley.’
Knowsley Village, England

“I got impatient,” Trimble says in an email to Mental Floss. “Now there’s increasingly more little detours and day trips” to track down new bin designs, he says, “which my friends, family and workmates patiently let me drag them on.” He has even pulled over on the road just to capture a new bin he spotted.

So far, he’s found cans that are blue, green, brown, black, gray, maroon, purple, and red. Some are only one color, while others feature lids of a different shade than the body of the can. Some look very modern, with minimalist logos and city website addresses, Trimble describes, “while others look all stately with coats of arms and crests of mythical creatures.”

A black trash can features an 'H' logo.
Hertsmere, England

A blue trash can reads ‘South Ribble Borough Council: Forward with South Ribble.’
South Ribble, England

A green trash can with a crest reads ‘Trafford Council: Food and Garden Waste Only.’
Trafford, Greater Manchester, England

Trimble began putting his images up online in 2017, and recently started an Instagram to show off his finds.

For now, he’s “more than managing” his one-can-a-week goal. See the whole series at

All images by Harry Trimble

Live Smarter
GoPro Will Let You Trade in Your Old Digital Camera for One of Their Cool New Ones

If your camera is aging, GoPro just gave you a great incentive to trade it in for a new model. The company has launched a buyback program that discounts its latest models if you send in your old camera, according to TechCrunch.

If you participate in the GoPro TradeUp program, the company will lop $50 off the price of the new GoPro HERO6 Black and $100 off the price of the Fusion, both released in late 2017. The offer applies to any digital camera—GoPro or not. Now might be a good time to offload that digital point-and-shoot you’ve been sitting on. (It does have to have an original retail value of at least $100.)

GoPro tried a similar initiative in 2017, giving customers 60 days to send in older GoPro models and get a discount on new models. Almost 12,000 customers answered the call. Now, the company is bringing it back with no end date, and the program will now accept any digital camera, whether GoPro-made it or not. “Dented, dinged, destroyed—no problem, we’ll take it,” the site promises.

If you’re already looking to get a new camera and want to dispose of your old one properly, this is a good way to do it. According to the company, “returned cameras will be recycled responsibly via zero landfill and recycling methods appropriate to material type.”

When you order one of the two available GoPro models through the TradeUp program, the company will direct you to dust off your old camera and send it in, with shipping costs covered. Once GoPro receives your old camera, it will send you the discounted new one.

With the discounts, a HERO6 Black would cost $350, and the 360°-shooting Fusion would cost $600.

[h/t TechCrunch]


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