Earning A Merit Badge With A Pinewood Derby Photo Finish

February 1, 2012 by Brian Benchoff 36 Comments

2/4 store-bought bodies

As a boy scout properly acculturated into the DIY philosophy, [Adam] really wanted to get his hands on the new Inventing merit badge. The merit badge required solving a problem, so of course a pinewood derby instant replay system was the obvious solution.

After thinking through a few solution paths like a radio-controlled camera that follows the cars, [Adam] settled on a system that would replay the pinewood derby cars crossing the finish line. [Adam]’s father found a cheap and readily available Playstation Eye camera that can record 60fps video for this task. [Adam] used a laser/photodiode/Arduino setup to detect when a car was crossing the finish line. A bit of Processing code supplied by his father records the relevant 60 frames of video and plays them at 5fps on a projector for the enthralled spectators.

We suspect that a similar setup could be used if [Adam]’s den wanted to try the rain gutter regatta or oft-forgotten space derby next year. Check out [Adam]’s instant replay system after the break, or join us in the comments for the inevitable argument over who had the best pinewood derby car.

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Lens Adapter From A Plastic Soda Bottle

February 1, 2012 by Mike Szczys 3 Comments

This lens adapter makes a lot of sense if you’re looking to interface with cameras that don’t have an in-built mounting option. It uses the cap and threaded neck from a soda bottle (translated) to make the lens adjustable and removable.

In the past we’ve seen this hack using a lens cap with a hole drilled in it as the mounting bracket. But that’s only useful if the lens you’ve chosen actually has a cap to use. This method lets you cut the top off of a the soda cap and mount it on the camera. Now each lens can be affixed to the threaded neck of the bottle, allowing for some adjustment of the focal point by screwing the add-on in or out.

Obviously this would work well for macro or fish-eye lenses. But there’s all kinds of other options out there like adding a microscope lens adapter, or actually attaching quality optics to your device.

DSLR Performance Measured With Audio Editing Software

January 27, 2012 by Mike Szczys 16 Comments

[Jaroslav’s] camera didn’t have a feature to measure the speed of its response in different modes so he figured out his own method. Using the microphone on his webcam he recorded the sound made by the mirror and shutter movements, then used Audacity to analyze the camera’s performance.

When you get right down to it, this is a fantastic idea. Audacity, the open source audio editing suite, has the ability to show each captured audio track next to each other. That makes it easy for you to precisely align the clips, and has in-build time measuring features with fantastic resolution.

He tested a whole bunch of different settings on a Canon EOS600D DSLR camera. In the image above you can see him comparing performance between different ISO settings. He also looks into different brands and sizes of SD storage cards, as well as the time difference when storing raw image data versus JPEG encoded data.

Reusing An Old Pacemaker As A Flash Timer

January 19, 2012 by Mike Nathan 26 Comments

pacemaker-flash-timer

Most people use pacemakers to, you know, keep their heart pumping at a steady rhythm. [David Prutchi] on the other hand has found a pretty novel use for some of the old pacemakers he has in his collection.

We really had no idea that pacemakers had uses outside the world of medicine, but [David] has taken advantage of their reliability in one of his favorite hobbies – high speed photography. In a darkened room, he set up an infrared barrier which feeds its signal to the atrium input of an old pacemaker. The signal is relayed through the ventricular output, which then fires his camera’s flash.

The pacemaker allows [David] to set an “AV” delay, which is the interval between when the atrium input receives an electrical impulse and when that signal is repeated from the ventricular output. This allows him to finely tune how much time elapses from when a drop of milk breaks the IR barrier to when his flash actuates.

We think this is a pretty cool way to reuse an old pacemaker, but check out the shots he has captured and judge for yourself.

Turn Your Camera Phone Into A Geiger Counter

January 15, 2012 by Brian Benchoff 96 Comments

Next time you’re waiting in the security line in an airport, why don’t you pull out your smartphone and count all the radiation being emitted by those body scanners and x-rays? There’s an app for that, courtesy of Mr. [Rolf-Dieter Klein].

The app works by blocking all the light coming into a phone’s camera sensor with a piece of tape or plastic. Because high energy radiation will cause artifacts on the CMOS camera sensor inside the phone, radiation will be captured as tiny specks of white light. The title picture for this post was taken from a camera phone at the Helmholtz Research Center in Munich being bathed in 10 Sieverts per hour of Gamma radiation from the decay of Cesium-137.

We have to note that blips of ‘bad data’ from a CMOS camera sensor aren’t unusual. These can come from electrical weirdness in the sensor itself or even the heat from the battery. [Rolf]’s app takes a reading of the noise floor and subtracts it from the counter. Radioactive decay resulting in Beta particles such as the Potassium-40 in bananas or the Uranium in granite counter tops don’t really register, although [Rolf] did have some success with Potassium chloride and a long measurement time. Still though, it’s a really cool way to turn a phone into a tricorder.

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Laser-triggered Camera Rig Update: 2011 Version

January 13, 2012 by Mike Szczys 5 Comments

[Fotoopa] keeps churning out new iterations of his laser-triggered camera rig. This is his latest, which he calls the 2011 setup. Regular readers will remember that we just covered a different version back in November; that one was the 2010 rendition. It had two DSLR cameras offset by 90 degrees with mirrors to face forward. This time around he has gone back to the single camera setup which was what he used on the first and second versions seen way back in 2008.

Whew, that’s a lot of links to specialty DSLR hardware. Let’s bring it back to this newest model (the link at the top). The biggest improvement is the shutter delay between when the laser beam is tripped and the image is take. [Fotoopa] reports that he’s managed to reduce that time down to 3.3 milliseconds. This is thanks to an external shutter replacement which improves on the stock shutter’s 52 millisecond delay.

For those that are seeing this for the first time. [Fotoopa] uses this rig to photograph insects in motion. A laser trip wire is responsible for triggering the shutter, and it does so with stunning results!

Build An Intervalometer With These Simple Fabrication Techniques

January 9, 2012 by Mike Szczys 4 Comments

[L] just finished building this intervalometer and his verbose documentation of the project has a little bit of everything. The fabrication uses common prototyping materials, and simple skills that are easy to master even for the beginner.

The hardware is based around an ATmega8 microcontroller. After snooping around the Internet [L] wanted to see if the voltage divider based focus and shutter commands that are present in some camera remote shutter controls would work for his model. Investigation with a commercial shutter release showed him how it was done, so he incorporated that into his design. When it comes to firmware for the device we really like his explanation of the menu system. There’s a lot of settings and he did a great job of planning the user interface to make them all work on the finished product.

The schematic and board layout were done with Eagle. During the layout process he made choices for easy assembly using strip board, and even walks us through the steps when cutting the traces and adding jumper wires. It’s nicely finished in this clear plastic case and demonstrated in the video after the break.

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