( ( An ( RKE eyepiece ) ) ( ( has ( ( ( ( ( an ( achromatic ( field lens ) ) ) and ) ( double ( convex ( eye lens ) ) ) ) , ) ( ( a ( reversed adaptation ) ) ( of ( the ( Kellner eyepiece ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT An) (NNP RKE) (NN eyepiece)) (VP (VBZ has) (NP (NP (NP (DT an) (JJ achromatic) (NN field) (NN lens)) (CC and) (NP (JJ double) (NN convex) (NN eye) (NN lens))) (, ,) (NP (NP (DT a) (ADJP (JJ reversed)) (NN adaptation)) (PP (IN of) (NP (DT the) (NNP Kellner) (NN eyepiece)))))) (. .)))
An RKE eyepiece has an achromatic field lens and double convex eye lens, a reversed adaptation of the Kellner eyepiece.
(ROOT (S (NP (NP (DT The) (NN lens)) (PP (IN of) (NP (DT the) (NN eye)))) (VP (VBZ is) (S (NP (DT a) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NN convex)) (VP (VB shape)))) (. .)))