15lb sandbag 20 c stand 216 diffusion 250 diffusion 251 diffusion 25lb sandbag 35lb sandbag 40 c stand
Adjustable lens opening controlling light transmission and depth of field measured in f-stops or t-stops.
Definition
The aperture (German Blende) is the adjustable opening in the lens that regulates the amount of light hitting the sensor or film. It is specified in f-stops or T-stops.
Aperture Scale
The aperture scale follows a mathematical progression:
f/1.4 – f/2 – f/2.8 – f/4 – f/5.6 – f/8 – f/11 – f/16 – f/22
Each stop halves or doubles the amount of light:
- Smaller number (f/1.4): Wide opening, more light, shallow depth of field
- Larger number (f/16): Narrow opening, less light, deep depth of field
f-Stop vs. T-Stop
- f-Stop: Geometric ratio (focal length / diameter)
- T-Stop: Actual light transmission (including glass loss)
Cinema lenses are calibrated in T-stops for precise exposure control.
Effect on the Image
- Exposure: Regulates the amount of light
- Depth of Field: Determines the focus range
- Image Quality: Diffraction blur at very small apertures
- Bokeh: Character of the out-of-focus areas
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