Shutter speed(exposure time)
Theeffectivetime thecamerashutter isopento allow
light to enter the camera and reach the sensor/focal
plane.ƒ-stop(focal ratio)
Theƒ-numberisthefocallengthdividedbythe‘effective’
aperture diameter.ISO (film sensitivity)
Before the introduction of digital photography, the
photographerwouldhavechosena particularfilmforits
sensitivitytolight.Thiswasreferredtoasthespeedofthe
film,orISOvalue.Thephotographerwouldhavehadto
physicallychangetherolloffilmshouldherequireafilm
with a different speed (ISO).
Withthedigitalsystemsnowinplace,andthesamevalues
applied to ISOs, thankfully this is no
longeranissue,astheimagemakercanchangetheISO
valuefrom shotto shot,making theprocessmuchmore
usable and flexible.
ThelowertheISOthefiner(smaller)thegrainofthefilm
and the less sensitivity to light. These were generally
referred to as slow films, as they would need slower
exposuretimestocaptureimages.ThehighertheISOthe
morecoarse(larger)thegrainofthefilmandthegreater
sensitivitytolight.Theseweregenerallyreferredtoasfast