High-Speed Camera Grabs First 3D Shots of Untouched Snowflakes 79
sciencehabit writes "Researchers have developed a camera system that shoots untouched flakes 'in the wild' as they fall from the sky. By grabbing a series of images of the tumbling crystals—its exposure time is one-40,000th of a second, compared with about one-200th in normal photography—the camera is revealing the true shape diversity of snowflakes. Besides providing beautiful real-time 3D snowflake photographs from a ski resort in Utah, the goal is to improve weather modeling. More accurate data on how fast snowflakes fall and how their shapes interacts with radar will improve predictions of when and where storms will dump snow and how much."
Re:Did the Penny Drop! (Score:5, Informative)
Previous Story: "Show me the money"
This story: "Here's the snowflakes! And the money."
Just in case this page gets updated and the penny gets bumped off, hopefully the direct link to the beautiful high-speed photo of a falling penny [utah.edu] will persist in the records and the annals of time forever.
Re:Did the Penny Drop! (Score:4, Informative)
It's certainly an unusual shape for a snowflake untouched by human hands.
And just the other day I was looking a photograph of snowflakes caught on felt, which left them unaffected.
Sometimes you don't need uber technology, but the creativity of a person on a very limited budget.
why not post the text that comes with the pics! (Score:2, Informative)
rather than the bs from sciencemag?
here it is:
"MASC Showcase: Snowflakes in Freefall
For more information about this University of Utah and National Science Foundation project please visit the Snowflake Stereography and Fallspeed home page or email Tim Garrett.
This is a gallery of snowflake images captured in freefall at Alta Ski Area using the University of Utah MASC (Multi Angle Snowflake Camera). When it is snowing, images of snowflakes captured live in free fall can be found at Alta's Snowflake Showcase.
Images are taken at f/5.6 with an exposure of up to 1/40,000th of a second using 1.2MP and 5MP industrial cameras with lenses ranging from 12 mm to 35 mm. The image resolution ranges from 9 micrometers to 40 micrometers.
Click on any image to see it in full resolution and to play a slide show.
Donations to continue the Snowflake Showcase at Alta Ski Area are welcomed.
Re:Nice pictures (Score:5, Informative)
Analogy fail. You must live somewhere warm... hate to break it to you, but snowflakes are real ;)
Bad summary (Score:5, Informative)
First, 1/200s is a very common shutter speed, yes, but most cameras can shoot at at least 1/2000s and most high-end cameras can shoot at 1/8000s...assuming, of course, you have enough light.
Most high-speed stills photography is actually done with a slow shutter speed; perhaps even a shutter left open for a couple seconds. Motion is stopped by the short duration of the flash burst. And with, for example, a Canon 580 EX II flash, you can get a 1/35,000s flash duration. Granted, this will be at minimum power...but they're operating at macro distances, where you can put the flash head almost on top of your subject and still overpower the subject with light.
Don't get me worng; this team is doing some nifty stuff. But it's also something that most professional photographers could easily replicate with the equipment they already have -- and that anybody who specializes in macro photography will probably already plan on playing around with next winter after reading this article.
What the team is doing that's interesting isn't the photography. It's the 3D reconstruction and subsequent analysis and modeling. Making it seem that it's about the photography, which is the easy and inconsequential part, really detracts from the good stuff.
Cheers,
b&
Re:Did the Penny Drop! (Score:2, Informative)
Go look at the pictures. Stop and go look at them. I guarantee they look nothing like he ones you saw on the felt. They flatten when they hit something, the ones in those pictures are not flat.
So yeah felt is a nice low tech way to take a look at them, but to really see what is happening the camera gives you so much more detail and dimension.
Image quality (Score:4, Informative)
All of these images are low res and out of focus.
Photographing falling snowflakes is probably pretty tricky, but some of them are just awful.
eg.
http://www.inscc.utah.edu/~tgarrett/Snowflakes/Gallery/2013.01.27_06.25.55.5_flake_17839_cam_2.png [utah.edu]
http://www.inscc.utah.edu/~tgarrett/Snowflakes/Gallery/2012.02.18_22.43.52_flake_1406_cam_2.png [utah.edu]
http://www.inscc.utah.edu/~tgarrett/Snowflakes/Gallery/2012.11.09_06.14.16_flake_107_cam_0.png [utah.edu]
http://www.inscc.utah.edu/~tgarrett/Snowflakes/Gallery/2013.02.22_16.06.08.425688_flake_16605_cam_1.png [utah.edu]
Re:Bad summary (Score:4, Informative)
The trick is that the shutter isn't doing the work; the flash is. It's possible to make very short flash pulses; I think you can make them even shorter than the 1/50,000 second mentioned in the article. As long as most of the light for the photograph comes from the brief but intense flash, the ability to freeze action depends on the flash speed rather than the shutter speed. You actually need to make sure the shutter speed is slow enough that the shutter is guaranteed to be all the way open when the flash triggers (X-sync speed or slower), or only the area behind the open part of the shutter will be exposed. Controlling things using the flash also guarantees that the multiple cameras used for 3D photography will all be taking their pictures at exactly the same instant.
Also note that the limitation you're talking about only applies to focal plane shutters (i.e. those right in front of the film or sensor). It's also possible to use a central shutter that's located right next to the iris of the lens. Central shutters open and close like the lens aperture, but block the lens completely when they're closed. Like the lens aperture, they block light to all parts of the focal plane more or less equally as they open and close, so they don't induce any of the motion effects that focal plane shutters do. Central shutters have their own problems- it's hard to make them work for very short shutter speeds, and they have limited efficiency when you use them that way because they're only completely open for part of the time- but they do eliminate focal plane shutter artifacts and allow you to flash sync at any available shutter speed.