Graphics Programs Reference
In-Depth Information
FIGURe 1.15
Narrow the depth of field by using a small f-stop ratio.
selecting Light sensitivity
Photographic film stocks had different sensitivities affecting how much light
was required to drive the chemical reaction. Fast-reacting film that was used
for shooting in low-light situations or to capture fast action was grainy, whereas
slow film was fine grained. Film speeds were measured using various standards
in the past, including DIN, ASA, and ISO.
In digital photography, we still use the ISO system to calibrate the light sensi-
tivity of the sensor (see Figure 1.16). Digital light sensors are far more sensitive
to light than film with ISO equivalents up to 102,400.
Just to put modern
iSO capabilities in
perspective, the
original Kodachrome
film had an iSO of 6.
O
FIGURe 1.16
Exposure is
a combination of shutter speed,
f-stop, and ISO value.
