I recently picked up a Sigma 10-20mm f/4-5.6 ultra-wide-angle lens for my Pentax K-5 II DSLR. On the first day that I took it out, I tried using a 1000x neutral density filter to blur water in a stream. The results were disappointing:
Even though the light was pretty dull, I attributed the bright horizontal streaks to lens flare from the cheap, uncoated filter, and I didn’t think much more about it.
Via PC Gaming Tips, “An apodizing phase plate coronagraph for VLT/NACO”:
Abstract: We describe a coronagraphic optic for use with CONICA at the VLT that provides suppression of diffraction from 1.8 to 7 lambda/D at 4.05 microns, an optimal wavelength for direct imaging of cool extrasolar planets. The optic is designed to provide 10 magnitudes of contrast at 0.2 arcseconds, over a D-shaped region in the image plane, without the need for any focal plane occulting mask.
Apodizing, of course, means “if you take cool extrasolar planet pictures with our coronagraph, they’re sure to end up on APOD.”
