Assertion: eyepiece's element | /r/CapableOf | act like a barlow lens
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text: this eyepiece, with its wide (82 degree) field of view and high optical quality, even on telescopes with fast focal ratios (partly explained by the fact that the first two elements of the eyepiece, shown here on the right, act like a Barlow lens) is generally felt to have sparked a revolution in deep-sky observing.