Recording Results
Before I go any further I should point out that this test is only going
to produce a theoretical result. Since I am testing film, the dynamic
range that I will be calculating will be much higher than any figure
normally quoted for film because very small changes will be detected. At
some point these changes will become irrelevant to the appearance of the
image but since this is a subjective judgement I'm going to leave it at the
calculated value for now. I'll return to the subjective arguments
later.
To counter tonal compression in highlights and shadows, the contrast of
each image should be adjusted to cover the full range. This will accentuate
any change between the grey rectangle and the background. Once there is no
difference between the two, both will become a homogenous area of noise.
The scanned images converted to 8-bit greyscale without any optimisation.
Since film scanners are designed to scan transparency film, it had no
trouble scanning the entire density range of the negative film. I could have
normalised the results (minimum pixel value was 84) to exaggerate the
differences but this would not have made any difference to subjective
comparisons, so I have left the data in its original state.
Here are my test results:
Settings
| Film |
Fuji Reala |
| ISO |
100 |
| Processing |
PRISM Colour |
| |
|
| Scanner |
Nikon Coolscan |
| Colour Management |
Use Nikon Colour Management |
| Colour Model |
Scanner RGB |
| Autoexposure |
OFF |
| Digital ICE |
OFF |
| Bit Depth |
12 bits/pixel |
| Multi-sampling |
4 |
Scanned Images
| Exposure |
1/8000 @ f8 |
1/4000 @ f8 |
1/2000 @ f8 |
1/1000 @ f8 |
1/500 @ f8 |
Raw
image |
 |
 |
 |
 |
 |
Adjusted
image |
 |
 |
 |
 |
 |
|
| Exposure |
1/250 @ f8
(metered exposure) |
1/125 @ f8 |
1/60 @ f8 |
1/30 @ f8 |
1/15 @ f8 |
Raw
image |
 |
 |
 |
 |
 |
Adjusted
image |
 |
 |
 |
 |
 |
|
| Exposure |
1/8 @ f8 |
1/4 @ f8 |
1/2 @ f8 |
1" @ f8 |
2" @ f8 |
| Raw image |
 |
 |
 |
 |
 |
| Adjusted image |
 |
 |
 |
 |
 |
|
| Exposure |
4" @ f8 |
8" @ f8 |
15" @ f8 |
30" @ f8 |
30" @ f5.6 |
| Raw image |
 |
 |
 |
 |
 |
| Adjusted image |
 |
 |
 |
 |
 |
|
| Exposure |
30" @ f4 |
|
| Raw image |
 |
| Adjusted image |
 |
Measurements
Mean Pixel Values
| Relative EV |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
| Black |
84.87 |
85.11 |
85.56 |
87.28 |
93.16 |
108.25 |
135.32 |
162.49 |
185.92 |
205.99 |
221.41 |
| Grey |
85.28 |
86.51 |
89.92 |
100.62 |
123.66 |
151.91 |
176.72 |
198.00 |
214.60 |
229.28 |
238.31 |
| White |
89.44 |
98.09 |
113.68 |
139.17 |
166.48 |
190.66 |
208.88 |
224.29 |
235.44 |
242.20 |
245.96 |
|
|
| Relative EV |
12 |
13 |
14 |
15 |
16 |
17 |
18 |
19 |
20 |
21 |
| Black |
233.13 |
240.33 |
244.60 |
247.15 |
248.74 |
249.54 |
250.07 |
250.60 |
250.95 |
251.11 |
| Grey |
243.53 |
246.53 |
248.57 |
249.63 |
250.20 |
250.46 |
250.84 |
251.16 |
251.37 |
251.51 |
| White |
248.31 |
249.60 |
250.32 |
250.73 |
251.00 |
251.13 |
251.33 |
251.47 |
251.53 |
251.59 |
Differences in Mean Pixel Values
| Relative EV |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
| Grey - Black |
0.41 |
1.40 |
4.36 |
13.34 |
30.50 |
43.66 |
41.40 |
35.51 |
28.68 |
23.29 |
16.90 |
| White - Grey |
4.16 |
11.58 |
23.76 |
38.55 |
42.82 |
38.75 |
32.16 |
26.29 |
20.84 |
12.92 |
7.65 |
| White - Black |
4.57 |
12.98 |
28.12 |
51.89 |
73.32 |
82.41 |
73.56 |
61.80 |
49.52 |
36.21 |
24.55 |
|
|
| Relative EV |
12 |
13 |
14 |
15 |
16 |
17 |
18 |
19 |
20 |
21 |
| Grey - Black |
10.4 |
6.2 |
3.97 |
2.48 |
1.46 |
0.92 |
0.77 |
0.56 |
0.42 |
0.40 |
| White - Grey |
4.78 |
3.07 |
1.75 |
1.10 |
0.80 |
0.67 |
0.49 |
0.31 |
0.16 |
0.08 |
| White - Black |
15.18 |
9.27 |
5.72 |
3.58 |
2.26 |
1.59 |
1.26 |
0.87 |
0.58 |
0.48 |
Graphical
So what does it all mean, and what else can we tell about the image
tonality? Read on.... |