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nobody

01 Feb 2012 17:13



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Mai simplist spus, masca de apertura aflata la o anumita distanta de oglinda va avea o proiectie extraaxiala eliptica care influenteaza astigmatismul. Indirect se schimba si planul focal optim (median) in care aberatiile combinate sunt la minim.

"As mentioned, presence of astigmatism significantly alters image field curvature properties. The Petzval surface becomes fictitious, and the actual best image surface becomes the one containing best astigmatic foci. Due to the longitudinal extension of astigmatism, this image is split into sagittal, tangential and best, or median image surface sandwiched in between the first two."