Friday, March 14, 2014

A brief sidebar - Time Lapse Photography

I've always wanted a time-lapse camera! When I was a kid my dad (Eric Carr) built a time lapse camera attachment to go on the family movie 8 camera. If you pushed the switch one way the camera took movies. If you pushed it the other way, it took one frame. My father built an apparatus that worked on a clock motor that would push the 'one frame' button once a minute or so. I remember the wonder of a home-made time lapse movie.

Last month I picked up a rather nice Fuji digital camera, but it doesn't have a time-lapse function. I have researched and found some Canon cameras can have a software 'hack' to allow internal programmed time lapse, but my Fuji camera doesn't support that.

So I went back to my father's idea. I built a frame to hold the camera and bought a small gear-motor that runs on DC power. I decided that I wanted the setup to run on 12 volts DC so that I could run it off a car battery when out camping or fossil hunting. A variable voltage power supply is easy to make from a Texas Instrument LM338 variable voltage power chip and a couple of components. This will allow the gear-motor to be supplied with a variable DC voltage, changing the rotation speed and changing the time between pictures. Since the camera has to be on the whole time that a movie is made, the internal batteries won't last long enough. So I also made a secondary power supply using a second LM338 voltage regulator that supplies a fixed 5 volt supply to run the camera off the car battery. A link to Texas Instruments: Voltage Regulator link

So here's a picture of the components. A tripod to hold the camera, the mounting block/power supply, 12 volt battery, camera.

 Here it is in operation:

video

Once you take a series of pictures they have to be assembled into a movie. Lots of freeware is available to do that. I used A freeware version of Video Velocity from Candylabs. Here's their website: Candy Labs Software . The freeware is limited in what it can do, but it OK to assemble a simple video. I took about 1200 photos over a 3 hour period at the OMSI Paleo lab showing Bernie's rock as we worked on it. It's pretty boring but it shows what can be done. 
video


Tuesday, March 11, 2014

X-Rays of the Fossil Jaw

X-Rays of the fossil jaw

Dan O'Loughlin of the NARG group, who is a veterinarian, has been nice enough to try to X-ray a jaw fragment that has teeth in it. It turns out that 'how teeth are connected to the jaw bone' is an important criteria in the classification of animals. Here's a link to a web article: http://qilong.wordpress.com/2010/07/22/tooth-implantation-pit2/ and of course there is a lot more info available. 
First of all, here's a picture of the jaw fragment in question: 
It has nice teeth, well connected into the jaw. I picked it since the teeth in the skull look exactly like this, so we know this fragment and the skull go together. 

Next, Dan took X-rays using several different settings of time, intensity and wavelength. A few are attached:



Finally, I took one of the best photographs and tried to manipulate it so as to improve the contrast around the tooth root which is important for this classification: 
 Picture manipulated to improve root contrast:
Even after all this not much can be seen. This can be because the normal tissue space occupied by ligaments in living organisms is all filled with minerals from the matrix - in this case calcium carbonate (limestone). If we need more data another analysis is needed - perhaps at the synchrotron facility at the U of Texas in Austin!