Focus Stacking

I have a new article on focus stacking.  Focus stacking is needed when the object photographed is smaller than a certain size.  This size does not depend on the camera sensor size or the magnification.  This size (in units of the wavelength of light) is approximately equal to the number of pixels in the sensor.

Winding Demagnetizer Coil

I have added a link to a new article: Winding Demagnetizer Coil.  This describes the construction of a coil for use with my instant demagnetizer.  The secret to good performance is to use a lot of copper, which makes the unit heavy and a bit expensive.

Instant Demagnetizer

I have added a link to a new article  "Instant Demagnetizer." This describes a device I built that allows us to use a withdraw-object-slowly-from-the-coil type of demagnetizer to an instant one that generates a decaying oscillating magnetic field. Just put the object to be demagnetized in the coil and press the button. Done!