FILTERS, WINDOWS & RETICLES

For the budding diffraction detective in your life, this Spectroburst™ Viewer is a diffraction-viewing lens and light kit from Spectroclick, which, if you ask us, is a pretty good name for a company that makes Spectroburst™ Viewers. Comes with (2) different diffraction gratings: blue (500 line/mm single dispersion), and red (200 line/mm double-axis) and a magnetic flashlight with solid/flashing modes. You rotate the frames to see kaleidoscopic patterns. Warning: Never look at the sun or a laser directly.

Al Luebbers, our founder, collected glass. Not glass like you'd find on a knick-knack shelf, but optical glass. Lenses, prisms, reticles and filters, for example. Focus on the filters. Many of his filters came out of military surplus, and this is for-real stuff. We mean many are solid dyed optical glass, ground and polished to flatness standards that were probably excessive. Others are from the old days in photographic optics, and their standards were even tighter than your militaristic Uncle's. We've found that photographers, artists, and optical designers still have an occasional need for good glass filters, so we're making a list of some goodies. As always, don't be timid about calling for quotes on quantities. If we have 'em, we'll sell 'em. Just don't sell them back. Please!

One wiseacre assumed we meant any package leaving our shipping room that once had a glass object in it. That is a malicious rumor. . . Ground glass is thin plate glass, the surface of which has been physically ground or acid-etched to create a grainy, grayish, opaque surface. Use it to produce an image from a lens or lens system. Even a simple magnifier, held between the ground glass and, say, a window, will produce an image of the window scene on the ground glass. Ground glass has another magical property: it is opaque to any object viewed at a distance, but not if that object is in direct contact with the glass surface. A necessary element of your optical education. 3-1/2" x 4-3/8" x 1/16" thick.

Let’s say you’re the teacher’s pet, newly appointed to AV duty, and you want to provide maximum light transmission over the visible spectrum while minimizing infrared rays and heat transmission in the class slide projector (yup, there’s a reason you’re AV guy, not quarterback). Well, this heat-absorbing glass might be just the thing. It’s 47mm dia x 6mm thick and comes in a great little pouch, canvasy outside and soft as down inside (to prevent scratching), with a border of blue stitching.