As we saw earlier (Page 18), the lens system contains an adjustable diaphragm or iris formed from a series of flat interleaving metal blades. Turning an iris control ring at the near end of the lens barrel adjusts the size of this hole – the lens working aperture or f-stop.
The ring has a graduated scale with a series of standard f-stop settings. These relate to the proportion of the light passing through the lens system, and falling onto the pickup sensor (the CCD). You select a particular f-stop setting, by aligning it with an indicator mark.
The larger the maximum size of the lens aperture, the more light it will pass. When shooting under lower light levels, a camera using a fast lens (with a maximum aperture of ...
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