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  1. H

    Test of six small refractors

    The Cloudy Nights review of the William Optics Schmidt diagonal is odd in that it initially describes such poor optical quality that a star can't be brought to good focus and then claims that doesn't matter for terrestrial use. In terrestrial tests, diagonals of this design I've tried...
  2. H

    Test of six small refractors

    Thanks for posting the test results, John. I see the same change in color correction when my Tak SKY90 (f/5.6 Fluorite doublet) is combined with a prism diagonal. The CA fringes appear red without the prism and change to blue/purple with the prism. The prism also adds spherical correction which...
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