The Schneider-Kreuznach Retina-Curtagon 28mm f/4 is a 28 mm prime lens with a maximum aperture of f/4 for the DKL mount. Here are its field of view on different sensors, hyperfocal distances, Milky Way exposure limits and the cameras it fits.
Focal length
28 mm
Max aperture
f/4
Mount
DKL
Designed for
Full frame
Field of view by sensor
| Sensor | Diagonal angle of view | 35 mm equivalent |
|---|---|---|
| Full frame | 75.4° | 28 mm |
| APS-C (1.5×) | 53.6° | 43 mm |
| Canon APS-C (1.6×) | 51.6° | 45 mm |
| Micro Four Thirds | 42.2° | 56 mm |
Hyperfocal distance
| Focal length | f/5.6 | f/8 | f/11 | f/16 |
|---|---|---|---|---|
| 28 mm | 4.7 m | 3.3 m | 2.4 m | 1.7 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) | 11.3 s @ f/4 | 17.9 s |
| Full frame (45 MP) | 9.7 s @ f/4 | 17.9 s |
| APS-C (24 MP) | 9.2 s @ f/4 | 11.7 s |
Where to buy
B&H PhotoAmazonKEH (used)MPB (used)FAQ
What is the Schneider-Kreuznach Retina-Curtagon 28mm f/4 equivalent to on APS-C?
About 42 mm (1.5×) or 45 mm on Canon APS-C (1.6×).