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that is correct roger
if you can imagine a positive lens (convex) converging the light rays "prematurely" before they would without the lens, then you have "shortened" the path of light, thus reducing the (focal) length (a reducer)
the exact opposite for a "negative" (concave) system (a barlow) which "splays" the light further on from its normal path making the convergence point longer
thus it seems strange terminology to use "negative" and "amplifier" in the same sentence...... but there you go ha ha! it is correct!
pat
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