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  1. J

    Orion 8-24mm Pro Lanthanum Zoom

    Hi, for 60 deg of afov your eypiece field lens diameter is 2 * 20mm * tan(30 deg) or 23mm. The width of the whole EP is given as 2 inch and they offer a nice zoom function for the image... so zoom until the EP is 2" wide on screen and measure eyelens diameter (I get 18mm or so). So we either...