“Here’s a sample of a 80F/6 doublet. The spherical correction looks a little bit better than refractor100_2 , but colorcorrection is a bit worse. The image shows significant astigmatism. Since this model did not allow changing the setup of the doublet customers cannot fix this astigmatism themself. My rating here is about 1/3 wavefront and maybe 1/15 RMS or less, not taken the astigmatism in account” Markus Ludes (APM-Telescopes) Note: the two sets below are from the same type of telescope but represent two other examples |
