Normal lens
Appearance
In photography, the phrase normal lens is used for camera lenses that have a focal length which is roughly the diagonal of the image projected inside the camera. Camera lenses with a shorter focal length are called wide-angle lenses, those with a longer one telephoto lenses.
This gives a natural perspective.
Film format | Image dimensions | Image diagonal | Normal lens focal length |
---|---|---|---|
9.5 mm Minox | 8 × 11 mm | 13.6 mm | 15 mm |
APS C | 16.7 × 25.1 mm | 30.15 mm | 28 mm, 35 mm |
135 | 24 × 36 mm | 43.27 mm | 50 mm, 45 mm |
120/220, 6 × 4.5 (645) | 56 × 45 mm | 71.84 mm | 75 mm |
120/220, 6 × 6 | 56 × 56 mm | 79.20 mm | 80 mm |
120/220, 6 × 7 | 56 × 68 mm | 88.09 mm | 90 mm |
120/220, 6 × 9 | 56 × 84 mm | 100.96 mm | 105 mm |
large format 4 × 5 sheet film | 96 × 120 mm (image area) | 153.67 mm | 150 mm |
large format 8 × 10 sheet film | 194 × 245 mm (image area) | 312.51 mm | 300 mm |
- In Digital photography the situation is more complex. The sensor type diameter is not the sensor diameter:
- (*) refers to tv-tube diameters that were standards in the 50's. The normal lens focal length is roughly 2/3 of the TV tube diameter.
- (**) this is a mathematical calculation because most of the cameras have zoom lenses.
Sensor type | TV-tube diameter * | Image dimensions | Image diagonal | Normal lens focal length ** |
---|---|---|---|---|
1/3.6" | 7.1 mm | 4.00 x 3.00 mm | 5.00 mm | 5 mm |
1/3.2" | 7.9 mm | 4.54 x 3.42 mm | 5.68 mm | 5.7 mm |
1/3" | 8.5 mm | 4.80 x 3.60 mm | 6.00 mm | 6 mm |
1/2.7" | 9.4 mm | 5.37 x 4.04 mm | 6.72 mm | 6.7 mm |
1/2.5" | 10.2 mm | 5.76 x 4.29 mm | 7.2 mm | 7 mm |
1/2" | 12.7 mm | 6.40 x 4.80 mm | 8.00 mm | 8 mm |
1/1.8" | 14.1 mm | 7.18 x 5.32 mm | 8.93 mm | 9 mm |
1/1.7" | 14.9 mm | 7.60 x 5.70 mm | 9.50 mm | 9.5 mm |
1/1.6" | 15.9 mm | 10.5 mm | ||
2/3" | 16.9 mm | 8.80 x 6.60 mm | 11.00 mm | 11 mm |
1" | 25.4 mm | 12.80 x 9.60 mm | 16.00 mm | 16 mm |
4/3" | 33.9 mm | 18.00 x 13.50 mm | 22.50 mm | 23 mm |
(APS-C) 1/8" | 45.7 mm | 22.70 x 15.10 mm | 27.3 mm | 27 mm |
DX | n/a | 23.7 x 15.8 | 28.40 mm | 28 mm |
FF (35 mm film) | n/a | 36 x 24 mm | 43.30 mm | 50 mm |
(4 x 5 cm) | n/a | 49.0 x 36.7 mm | 61.22 mm |
- In cinematography a focal length roughly equivalent to twice the diagonal of the image projected within the camera is considered normal.
Film format | Image dimensions | Image diagonal | Normal lens focal length |
---|---|---|---|
N-8 | 3.68 x 4.88 mm | 6.11 mm | 12 - 15 mm |
Single - 8 (FUJI) | 4.22 x 6.24 mm | 7.53 mm | 15 - 17 mm |
Super - 8 | 4.22 x 6.24 mm | 7.53 mm | 15 - 17 mm |
9.5 mm | 6.5 x 8.5 mm | 10.70 mm | 20 mm |
16 mm, magnetical sound | 7.49 x 10.26 mm | 12.70 mm | 25 mm |
16 mm, optical sound | |||
35 mm | 18.00 x 24.00 mm | 30.00 mm | 60 mm |
35 mm, sound | 16.03 x 22.05 mm | 40.53 mm | |
65 mm | |||
70 mm | 52.6 x 23.0 mm | 57.41 mm |
According to the ASC Selected Tables, Charts, and Formulas for the Student Cinematographer (4th Edition, page 16), a normal lens is one with a focal length equal to the diagonal of the image format, not twice the diagonal. This definition is widely accepted within the cinematography community and reflects the standard used by professionals in the field.[1]
References
[change | change source]- ↑ ASC Selected Tables, Charts, and Formulas for the Student Cinematographer (4th Edition, page 16),.