Generally, when people choose a lens, they seldom consider the amount of blades in the lens’ aperture. But in fact, the amount of blades is very very important if your photography interests include photographing elements of light or the sun and love achieving that star effect.
The difference in aperture settings doesn’t only affect the Depth of Field (DOF) alone. In both of the photos below I used the Aperture Priority settings with 200 ISO.
By using a narrow aperture (f/10), the photograph requires more time to absorb light. This results in star-shaped light images in stationary light sources and the light tracks of the rotating Ferris wheel appear long (long exposure).
The use of a wide aperture setting (f/3.5) allows short exposure time, which produces spherical glow in the stationary light sources and short light tracks on the rotating Ferris wheel (freezing).
To achieve a crisp star-effect on your stationary light source when in low lighting conditions (like at night, for example), you’ll most likely need a tripod because the star effect relies on the narrow aperture settings. This means slower shutter speeds in low light conditions, which means a tripod is needed to keep the camera steady for longer periods of time.
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