Full Article
A short brief
Quite often we find that as we abruptly switch to another photographic shooting format, it takes some time to adapt to the focal lengths and angle of views in picking the choice of lenses, especially with lesser common focal lengths such as the Leica Summilux 75/1.4 , Summilux 80/1.4 , Summicron 90/2.0.
It's always handy to simply do a quick table look-up to match the scenes. However, for years, I still haven't come into one with data comprehensive enough to do the job. I chose to do a quick calculation on my own.
Corresponding Focal Lengths of Different Film and Sensor Formats
A Handy Conversion Table:
| Lens Types | Angle of View (Horizontal) | Small Formats (3:2) 135 Films | Cropped Medium Formats (4:3) | Full-Frame Medium Formats (1:1 / 4:3 / 1:1.2) 120 Films | ||
| APS-C | 35mm (135) | 44x33 mm | 48 x 36 mm | 6x6 / 645 / 6x7 | ||
| Ultra-Wide | 100° | 10 / 11 | 15 / 16 | |||
| 88° / 87° | 12 / 13 | 18 / 19 | 24 | |||
| 80° | 14 / 15 | 21 | 30 | 38 | ||
| 74° / 72° | 18 | 24 / 25 | 30 | 30 | 40 | |
| Wide-Angle | 65° | 20 | 28 | 35 | 40 | 50 |
| 54° | 23 | 35 | 45 | 50 | 60 | |
| Standards | 39° | 35 | 50 | 65 | 70 | 80 |
| 37° | 55 | 70 | 80 | 100 | ||
| Telephotos | 27° | 75 | 90 | 100 | 135 | |
| 25° / 24° / 23° | 60 | 80 / 85 / 90 | 110 | 120 | 150 | |
| 21° | 100 | 130 | 150 | 180 | ||
| 15° | 135 | 180 | 180 | 250 | ||
| Lens Focal Lengths in millimeters (mm) | ||||||
The table was compiled through calculated diagonal ratios, and then matched with available offerings from major camera manufacturers.
Camera Model Examples
with APS-C sensors: Leica CL / TL Systems ; Nikon DXX00 Series (DX format), Nikon Z50 ; Sony A7RS series ; Canon XXXD
with 35mm full-frame 135 sensors: Leica M, SL Cameras; Nikon D600, 700, D800 Series (FX format), Nikon Z series ; Sony A7R Series ; Canon EOS 5D, 6D
with medium format, 44x33 sensors: Hasselblad X1D, 907X, CFV 50C ; PhaseOne P30+, P40+,
with medium format, 48x36 sensors: Hasselblad CF-39, CFV-39, H5D-50 ; PhaseOne P45+
with medium format, full-frame sensors (from 54x40mm on): Hasselblad H5D-60, H6D-100C ; PhaseOne P65+, IQ160, IQ180 ; Leaf Aptus-II 10, 12 (56x36mm).
The Leica S system has a specific medium format sensor size, with an aspect ratio 3:2 (1.5) matching the 35mm 135 format, instead of the de-facto ratio of 1.33 (645). However, the sensor diagonal size is measured to match the format of 44x33 sensors. Therefore, focal lengths would also match with a slightly wider view-angle.
Leica S Systems: medium format, sensor dimension: 45x30 mm