Posts Made By: Duane Jaecksdvise

I recently purchased a 6" reflector. On the back of the mirror was a sticker labeled "Keim Precision Mirrors", Glendale, CA. Also on the back is etched the following, "Refigured by Cave Optical Co., 48" fl, F/8, Sept. 1957". Also etched is the name "McLouglin". Can anyone shed any light on the name McLoughlin or the Keim Co?
Duane H. Jaecks

Does anyone have any information on the quality of the apo lenses sold by various people in China? The one I familiar with is the great eye who sells on ebay. I am sure there are others. The prices are relatively low and I was wondering if these were manufacturers rejects.
Duane

These early Tascos are a real steal and for 100 dollars is a steal. The optical quality and workmanship is top notch. I hope you bought it.
Duane H. Jaecks

If you have a very good parabolic mirror with a diameter somewhat twice the diameter of the achromat you wish to test you can make a beam of "parallel" light rather easily by putting a bright point light source at the focal point. The returning beam can be used to test your lens with a knife edge, ronchi grating etc. Just put your filters behind the knife edge. I have been using this method for many years and it works great on small lenses too, which don't easily lend themselves to autocollimation techniques.
Duane Jaecks