V1.02
Thom Hogan’s Complete Guide to the Nikon D300
Page 65
8 Bits
14 Bits
First Stop
Values of 0 to 36
Values of 0 to 2340
Second Stop
37 to 73
2341 to 4680
Third Stop
74 to 110
4681 to 7020
Fourth Stop
111 to 146
7021 to 9361
Fifth Stop
147 to 183
9362 to 11701
Sixth Stop
184 to 219
11702 to 14042
Seventh Stop
220 to 255
14042 to 16384
It should be obvious that the data in each stop of exposure
has more potential subtlety in 14-bit data than in 8-bit data.
Thus, you’ll want to keep your data in the higher bit realm as
long as possible.
Fortunately, the D300 does just that. The EXPEED image
processing system does the image demosaic and applies
camera settings on 12-bits of data
24
. Only at the final stage of
creating the JPEG or TIFF does the D300 reduce data to 8 bits.
Better still, the D300 captures dark to bright in a somewhat
more predictable fashion
25
; 35mm film tends to have a widely
varying response (density of image) to exposure, producing a
distinct S-curve when you plot exposure against density.
Worse still, most film has a property called reciprocity
failure—the tendency to require a different exposure at
extremely short or extremely long shutter speeds. The bottom
line on digital tonality is that the shadow areas are less likely
24
Actually, the internal processing is done using 16 bits (the 12-bit value is pushed
into the top of those 16-bits; again, JPEG and TIFF only collect 12-bit data, NEF
collects 14-bit values).
25
“Predictable” isn’t quite the right word to use, as no imaging device I know of has a
perfectly predictable response to light. My point is that a D300’s tonality curve is
more regular than film’s, which tends to vary more with brightness and exposure
length.
