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nobody

10 Mar 2014 02:48



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Pentru cei interesati:
Wynne-type corrector offers excellent correction level with either paraboloidal or hyperboloidal mirrors (it is also used in two-mirror systems), both in regard to monochromatic aberrations and chromatism. However, while one of the three lens elements is a simple near plano-convex or PCX, the other two are strongly curved, thin menisci, very demanding in both, fabrication and positioning/centering.
Image field curvature is not a serious detriment to visual observing, due to the natural ability of the eye to accommodate (refocus). In photographic use, however, field curvature induces defocus error, which can be significant. In order to flatten curved image field, an auxiliary lens, or group of lens is placed in front of the final focus, offsetting image curvature by generating one of similar magnitude but opposite in sign.
http://www.telescope-optics.net/field_flattener.htm

Pe urma mai vine vignetarea. De aceea se folosesc focusere si corectoare de 2.5", 3" sau chiar mai mari, in special la corectorul Wynne.

P.S. Corectorul proiectat de Pal Gyulai (GPU Optics) nu este Wynne.
http://www.teleskop-austria.at/shop/index.php?lng=de&m=2&kod=bar2-kom-kor-4
http://komakorrektor.blogspot.co.at/
Observ ca testele sunt facute in general la f/5 si f>1000mm. Oare de ce ?
Si asa are o curbura a campului destul de sanatoasa.
Pe de alta parte, la camp mai ingust si focala mai mare, nu-i rau deloc.