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nobody

07 Mar 2018 11:59



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Corectoarele de coma de tip Paracorr sau Wynne aplatizeaza curbura campului, cel putin intr-o anumita masura, daca nu chiar complet.

Paracorr-like coma corrector for paraboloid - which also flattens the field - ...

Wynne corrector in its original form consists of a three or four singlets (doubling the middle lens in the standard 4-lens arrangement does not significantly improve performance). In addition to correcting for coma, it also flattens the field.
Paracorr also acts as a field-flattener.
NOTE: Curves shown are typical for mirror focal lengths in the 1200mm or longer focal length range. For focal lengths shorter than 1200mm, you might find some field curvature. In general, we recommend APS size formats, which would typically yield 90% illumination over a 30mm diagonal chip.
http://televue.com/engine/TV3b_page.asp?id=61&Tab=_phot

Desigur, astea costa.
Ceva mai ieftin (nu stiu cat de bun): https://www.astronomics.com/astro-tech-photo-visual-coma-corrector-field-flattener_p18124.aspx

La refractoare e mai complicat si e bine sa se foloseasca corectoare dedicate, de genul:
https://www.teleskop-express.de/shop/product_info.php/language/en/info/p3627_skywatcher-0-85x-reducer-und-flattener-fuer-ed-80-600.html

In general nu exista ceva si ieftin, si bun, si pentru toate.