It works because the maximum resolution of a telescope (the minimum angle apart that two points need to be for the telescope to see them as separate) depends on its diameter, not its collecting area.

ECONOMIST: Radio telescopes

When set at maximum aperture and widest angle of view the photographer can use fast shutter speeds in dimly lit locations and take advantage of a beautiful bokeh (out-of-focus) effect in the background.

ENGADGET: Pentax launches brass-bodied MX-1 point-and-shoot: 12MP with 4X zoom (update: now with hands-on photos)

Its newly designed, large-aperture, 4x optical zoom lens (with the maximum aperture of F2.0 at wide-angle end), high-sensitivity, back-illuminated 16 megapixel CMOS image sensor, and sensor-shift Shake Reduction system ensure sharp, high-quality, low-noise images.

ENGADGET: Pentax expands ruggedized series with Optio WG-3, Target-exclusive WG-10