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
|
|
| 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
|
|