To: atm{at}shore.net
From: "Matthew L. Brown" 
Reply-To: "Matthew L. Brown" 


I've had several off-list questions about how I make my foucaultgrams.  I
think the quality is due to the nice camera, a 5 megapixel Nikon coolpix
5000.  The tester is a mostly wood affair, with a fixed slit made of two
singled edged razor blades carefully propped underneath a screw.  The slit
is fairly wide, about 0.5mm.

I put the tester on one end of a long table, with the mirror propped at the
other end.  I set the camera to normal mode, no flash (duh).  No special
modes or settings.  The camera is on a tripod, which I wiggle into place
behind the tester each time.  First I back the knife edge completely off
and sight for the beam with my eye, noting where along the knife edge it
will hit.  Then I carefully slide the tripod approximately into place. 
Final alignment is done using the LCD display to guide me.  I zoom in to
the maximum optical zoom, and center the image on the screen where the
camera does its lighting and focus measurements.  Then I adjust the slit.

The high pixel count lets me zoom in quite close when I crop the image.  I
generally don't do any postprocessing like sharpening.

At first this setup was frustrating to use, and I promised myself I'd make
a camera mount for the tester.  But in time I've gotten fairly quick about
setting up, maybe 3 minutes, so now I record each and every test.  I think
the series might make an interesting animated GIF.


I generally recommend this camera for all around use.  Just don't cover the
focus sensor with your finger.  It now runs $650-800 on the web:
http://beta2.epinions.com/Nikon_Coolpix_5000_Digital_Camera__Camera_25501/displ
ay_~latest_prices


=Matt

--- BBBS/NT v4.00 MP