This is a doublet airspaced Fluorite Apo. It has a little bit of coma. In white light it looks to me something like 1/5 wavefront p.t.v and about 95% strehl, with green filter it looks more like 1/6 to 1/7 wavefront and 96% strehl. From 6 alike telescopes this one had the best spherical correction.The coma might still be removed with a better centering (collimation) of the element. Markus Ludes (APM-Telescopes) |
