V1.02
Thom Hogan’s Complete Guide to the Nikon D300
Page 281
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Alternatively: Hold down the
ISO
button and use the Rear
Command dial to select an ISO value.
Top LCD:
While it may seem that you should simply set the camera to
the highest ISO value and leave it there (or use the
Auto
function available in the Custom Settings), don’t. As you
increase the D300’s ISO value, your images lose dynamic
range capability and potentially gain considerable digital
noise. Much as using a higher ISO film in a 35mm film body
results in increased visible grain. Added digital noise makes
an image look rougher (most noticeable in large areas of a
single color). Worse still, digital noise added by the D300 is
not truly random, unlike film grain.
The D300 has a variety of noise reduction schemes, some of
which work automatically and some of which are user
controlled.
Long exp. NR
(on the SHOOTING menu) has
nothing to do with ISO: it controls a type of noise that builds
up when a sensor sits collecting light photons for long periods
of time (8 seconds or longer on the D300).
High ISO NR
(also on the SHOOTING menu) is a setting that
does
apply to noise caused by ISO settings. Because higher
ISO values are typically caused by amplifying data, small
inconsistencies in data are amplified as you increase the ISO
setting.
High ISO NR
is a setting used to combat that; it
begins working at ISO
800
or higher if specifically turned on
by you, but it is always active in some form at above ISO
HI
0.3
.
But noise reduction routines aren’t perfect, and they also have
a tendency to reduce edge definition.