How the astrophotography lens score works
For untracked astrophotography — no star tracker, just a camera on a tripod — the best lens is not simply the one with the widest aperture. Three things multiply together to decide how much starlight reaches your sensor in a single frame.
- Aperture area — the physical opening, focal length divided by f-number. A wider opening collects more light every second.
- Exposure time — how long you can expose before the earth’s rotation turns stars into trails, roughly 500 divided by crop factor divided by focal length.
- Field of view — how much sky the lens projects onto the sensor.
Multiply those three and you get the signal: the total starlight captured in one frame. The score is that figure on a decibel scale, expressed as a percentage of the highest-scoring lens, the Rokinon 24mm f/1.4.
This is why wide lenses dominate the ranking. A Rokinon 85mm f/1.4 has roughly twelve times the aperture area of the 24mm f/1.4, yet gathers only about a third as much total starlight — because it sees ten times less sky and must close the shutter three times sooner.
The score also uses each lens’s minimum usable f-number: the widest aperture actually worth shooting before coma and astigmatism smear the stars, rather than the headline maximum on the barrel. A fast lens that has to be stopped down scores like the slower lens it effectively becomes.
Highest-scoring full-frame lenses for nightscapes
| # | Lens | Focal length | Min usable | Max exposure | Score |
|---|---|---|---|---|---|
| 1 | Rokinon 24mm f/1.4 | 24 mm | f/1.4 | 21 s | 100% |
| 2 | Rokinon 35mm f/1.4 | 35 mm | f/1.4 | 14 s | 99% |
| 3 | Sigma 35mm f/1.4 Art | 35 mm | f/1.4 | 14 s | 99% |
| 4 | Zeiss Otus 55mm f/1.4 | 55 mm | f/1.4 | 9 s | 97% |
| 5 | Rokinon 85mm f/1.4 | 85 mm | f/1.4 | 6 s | 94% |
| 6 | Sony A Zeiss Planar T* 85mm f/1.4 ZA | 85 mm | f/1.4 | 6 s | 94% |
| 7 | Nikkor AF-S 20mm f/1.8G ED | 20 mm | f/1.8 | 25 s | 93% |
| 8 | Sony A Zeiss Distagon T* 24mm f/2 ZA SSM | 24 mm | f/2 | 21 s | 90% |
| 9 | Sony FE 28mm f/2 | 28 mm | f/2 | 18 s | 90% |
| 10 | Sony Zeiss FE 55mm f/1.8 ZA | 55 mm | f/1.8 | 9 s | 90% |
Use the tool above to filter all 380 lenses by brand and sensor format, compare lenses side by side, or calculate a score for any lens that is not listed.
Lens data and the “Lonely SpecMark” scoring system are the work of Ian Norman of Lonely Speck.