Dioptrix

Al and David Nagler were at TSP and demonstrated the soon to be released Dioptrix attachment that corrects for astigmatism. I was thrilled by the improvement it made in my view at the eyepiece. One needs to know the number of diopters of "cylinder" in the prescription for the eye you observe with. The attachment fits the TeleVue eyepieces that produce large exit pupils. Interestingly, I could notice a subtle improvement in my vision even with eyepieces that produced a 2mm exit pupil. I did not have the opportunity to try the Dioptrix attachment out under clear skies, it was demonstrated at the vendor building using an eye chart. I think that the more astigmatism one has the more one will appreciate this accessory. It will be extremely useful for observers with astigmatism when they use the 31 and 26 Naglers, for instance.