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Mark Schubin's Format Fundamentals |
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Format Factor Fundamentals by Mark Schubin
Dimensions in mm; figures rounded; diagonal determines lens format; AR is aspect ratio;
divide comparable dimensions for format factor; lp/mm figures for dimension with highest resolution; 1920 represents lp/mm at full-HD resolution.
To generate the Format Factor, divide the horizontal or vertical dimension of one format by another's (e.g., 2/3-inch format horizontal dimension of 9.6 mm divided by 1/3-inch format horizontal dimension of 4.9 mm is approximately 2:1).
To use the Format Factor for shot size or acceptance angle, divide the focal length of the larger format by the Format Factor (e.g., a 20-mm lens in 2/3-inch format offers approximately the same shot as a 10-mm lens in 1/3-inch format).
To use the Format Factor for sensitivity (assuming all else is equal), divide the f-number of the larger format by the Format Factor (e.g., f/8 in a 2/3-inch camera would be roughly equivalent to f/4 in a same-technology/same-resolution 1/3-inch camera).
To use the Format Factor for depth of field (in the non-macro, non-hyperfocal region), divide both the f-number and focal length of the larger format by the Format Factor (e.g, the depth of field offered by a 2/3-inch-format camera at f/8 and 20 mm would be roughly the same as that of a 1/3-inch-format camera a f/4 and 10 mm).
To use the Format Factor for contrast-reduction due to diffraction loss, divide the f-number of the larger format by the Format Factor (e.g., diffraction loss at f/8 in a 2/3-inch camera would be roughly equivalent to f/4 in a 1/3-inch camera).
The "1920" column has the Format Factor built in in estimating lens-quality requirements. Thus, a lens intended to offer the full 1920 pixels per line of HDTV would need to deal with 100 line-pairs per millimeter in a 2/3-inch format but almost twice as many in a 1/3-inch format.
Camera |
Diagonal |
AR |
:1 |
Width |
Height |
lp/mm |
1920 |
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| Vision Research Phantom 65 |
59.6 |
5:3 |
1.67 |
51.2 |
30.5 |
40 |
19 |
| Dalsa Origin, Evolution |
38.1 |
~2:1 |
1.98 |
34.0 |
17.2 |
60 |
28 |
| NAC Memrecam fx K4 |
35.6 |
5:4 |
1.25 |
27.8 |
22.2 |
23 |
35 |
| Super Hi-Vision 2.5-inch |
34 |
16:9 |
1.78 |
29.8 |
16.4 |
129 |
32 |
| Super 35 film |
31.1 |
4:3 |
1.33 |
24.9 |
18.7 |
-- |
-- |
| Weisscam HS-2 |
31.1 |
4:3 |
1.33 |
24.9 |
18.7 |
55 |
39 |
| Colorspace True35 (reported) |
30.0 |
4:3 |
1.33 |
24 |
18 |
43 |
40 |
| ARRI D20/21 |
30.8 |
4:3 |
1.33 |
23.8 |
17.8 |
61 |
40 |
| Vision Research Phantom HD |
29.1 |
16:9 |
1.78 |
25.6 |
13.9 |
40 |
38 |
| Red One |
28.0 |
16:9 |
1.78 |
24.4 |
13.7 |
93 |
39 |
| Panavision Genesis |
27. |
16:9 |
1.78 |
24.0 |
13.5 |
120 |
40 |
| 35-mm Academy aperture film |
27.3 |
11:8 |
1.38 |
22.0 |
16.0 |
-- |
-- |
| Photron Ultima APX-RS |
24. |
1:1 |
1 |
17.4 |
17.4 |
29 |
55 |
| Weinberger Cine SpeedCam |
20 |
~3:2 |
1.55 |
17 |
11 |
47 |
56 |
| Super Hi-Vision 1.25-inch |
19 |
16:9 |
1.78 |
16.6 |
9.2 |
231 |
58 |
| Weisscam HS-1 |
19 |
5:4 |
1.25 |
15 |
12 |
43 |
64 |
| 1-inch 1035-line HDTV |
16.0 |
16:9 |
1.78 |
13.9 |
7.8 |
69 |
69 |
| 1-inch 720-line HDTV |
16.0 |
16:9 |
1.78 |
13.9 |
7.8 |
46 |
69 |
| Super 16 film |
14.5 |
5:3 |
1.67 |
12.5 |
7.4 |
-- |
-- |
| 16-mm film |
12.7 |
11:8 |
1.38 |
10.3 |
7.5 |
-- |
-- |
| Ikonoskop a-cam dII |
12.2 |
16:9 |
1.78 |
10.6 |
6.0 |
90 |
90 |
| Olympus Octavision |
11.0 |
16:9 |
1.78 |
9.6 |
5.4 |
200 |
100 |
| Silicon Imaging SI-2K |
11.0 |
16:9 |
1.78 |
9.6 |
5.4 |
107 |
100 |
| 2/3-inch 1080-line HDTV |
11.0 |
16:9 |
1.78 |
9.6 |
5.4 |
100 |
100 |
| 2/3-inch 720-line HDTV |
11.0 |
16:9 |
1.78 |
9.6 |
5.4 |
67 |
100 |
| 1/2-inch 1080-line HDTV |
8.0 |
16:9 |
1.78 |
7.0 |
3.9 |
138 |
138 |
| 1/3-inch 1080-line HDTV |
5.6 |
16:9 |
1.78 |
4.9 |
2.7 |
197 |
197 |
| 1/3-inch 720-line HDTV |
5.6 |
16:9 |
1.78 |
4.9 |
2.7 |
131 |
197 |
| 1/4-inch 1080-line HDTV |
4.5 |
16:9 |
1.78 |
3.9 |
2.2 |
245 |
245 |
| 1/5-inch 1080-line HDTV |
3.6 |
16:9 |
1.78 |
3.1 |
1.8 |
316 |
316 |
| 1/6-inch 1080-line HDTV |
3.0 |
16:9 |
1.78 |
2.6 |
1.5 |
379 |
379 |
Extended at arm's length
:
pinkie nail
pinkie
thumb width
thumb top to joint
three-finger salute
thumb length
clenched fist
thumbs touching (director)
Held to eye:
folded paper
paper corner
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Angle
~0.5°
~1°
~2°
~3°
~5°
~7.5°
~10°
~15°
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2/3-inch lens equivalent focal length
~1100 mm - Super Tele
~550 mm - tight end of 66x
~270 mm
~185 mm - tight end of ~20x handheld
~110 mm
~75 mm
~55 mm - tight end of wide-angle lens
~35 mm
~11 mm - 1/5 tighter than wide end of normal lens
~5 mm - near the wide end of a wide lens
| You can estimate shot sizes by extending your fingers at arm's length and using the following chart. You can estimate larger shot sizes by holding the corner of a piece of paper under your eye and sighting along the edges (90 degrees), folding it and doing the same (45 degrees), folding it again (22.5 degrees, like a paper-airplane dart), and unfolding just one side of the last fold (67.5 degrees, corner plus dart). The 2/3-inch focal lengths may be converted to other formats using the Format Factor chart above.
Table: Originally published, in somewhat different form, in Videography magazine in May 2007, updated by the author on June 15, 2009, used with permission.
Article riginally published in Videography magazine in May 2007, used with permission.
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