Assertion: lens's aperture | /r/ObjectUse | used in a one-third-stop system
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Source sentences:
text: Sometimes the same number is included on several scales; for example, an aperture of f/1.2 may be used in either a half-stop or a one-third-stop system; sometimes f/1.3 and f/3.2 and other differences are used for the one-third stop scale.