The Zeiss Carl Zeiss Jena Flektogon 20mm f/4 is a 20 mm prime lens with a maximum aperture of f/4 for the M42 mount. Here are its field of view on different sensors, hyperfocal distances, Milky Way exposure limits and the cameras it fits.
Focal length
20 mm
Max aperture
f/4
Mount
M42
Designed for
Full frame
Field of view by sensor
| Sensor | Diagonal angle of view | 35 mm equivalent |
|---|---|---|
| Full frame | 94.5° | 20 mm |
| APS-C (1.5×) | 70.5° | 31 mm |
| Canon APS-C (1.6×) | 68.1° | 32 mm |
| Micro Four Thirds | 56.8° | 40 mm |
Hyperfocal distance
| Focal length | f/5.6 | f/8 | f/11 | f/16 |
|---|---|---|---|---|
| 20 mm | 2.4 m | 1.7 m | 1.2 m | 0.9 m |
Circle of confusion 0.030 mm (sensor size the lens is designed for).
Longest exposure for sharp stars
| Camera | NPF rule (wide open) | 500 rule |
|---|---|---|
| Full frame (24 MP) | 15.8 s @ f/4 | 25.0 s |
| Full frame (45 MP) | 13.6 s @ f/4 | 25.0 s |
| APS-C (24 MP) | 12.8 s @ f/4 | 16.3 s |
Cameras that fit (2)
Where to buy
B&H PhotoAmazonKEH (used)MPB (used)FAQ
What is the Zeiss Carl Zeiss Jena Flektogon 20mm f/4 equivalent to on APS-C?
About 30 mm (1.5×) or 32 mm on Canon APS-C (1.6×).
Which cameras is the Zeiss Carl Zeiss Jena Flektogon 20mm f/4 compatible with?
It fits KMZ Zenit 122, KMZ Zenit 412LS (see the full list above).