Cameras¶
Camera Fundamentals¶
Pinhole camera: Light passes through a small aperture to form an inverted image. No lens required, but requires long exposure due to limited light.
Camera obscura: The principle behind all cameras — a dark room/box with a small hole projects an inverted image of the outside scene.
Lenses¶
Lenses gather more light than a pinhole and focus it onto the sensor:
Focal length: Distance from lens to image plane when focused at infinity. Determines field of view and magnification.
Depth of field (DOF): Range of distances that appear acceptably sharp. Controlled by aperture, focal length, and subject distance.
Lens equation: \(\frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i}\) where \(f\) = focal length, \(d_o\) = object distance, \(d_i\) = image distance.
Exposure¶
Exposure is the total amount of light reaching the sensor, controlled by three factors (the exposure triangle):
Aperture (f-stop): Size of the lens opening. Lower f-number = larger opening = more light, shallower DOF.
Shutter speed: Duration the sensor is exposed to light. Faster = less light, freezes motion.
ISO: Sensor sensitivity. Higher ISO = brighter image but more noise.
Sensors¶
Digital camera sensors convert photons to electrical signals:
CCD (Charge-Coupled Device): Sequential readout, lower noise, higher power
CMOS (Complementary Metal-Oxide-Semiconductor): Per-pixel readout, lower power, dominant in modern cameras
Bayer filter: Color filter array (RGGB pattern) over monochrome sensor; demosaicing interpolates full-color image
Sensor size: Larger sensors capture more light and produce less noise at the same ISO