The Apple iPhone XS (tele) uses the built-in lens (fixed-lens camera) with a 8.67× crop factor (about 4.2 × 2.8 mm sensor). Below: equivalent focal lengths, maximum shutter speeds for sharp stars, a hyperfocal distance chart and how to check the shutter count.
Equivalent focal length & field of view
| Lens focal length | Full-frame equivalent | Diagonal FOV | Horizontal FOV |
|---|---|---|---|
| 8 mm | 69 mm | 35.0° | 29.4° |
| 10 mm | 87 mm | 28.3° | 23.7° |
| 12 mm | 104 mm | 23.8° | 19.9° |
| 14 mm | 121 mm | 20.4° | 17.1° |
| 16 mm | 139 mm | 17.9° | 15.0° |
| 18 mm | 156 mm | 16.0° | 13.3° |
| 20 mm | 173 mm | 14.4° | 12.0° |
| 24 mm | 208 mm | 12.0° | 10.0° |
| 28 mm | 243 mm | 10.3° | 8.6° |
| 35 mm | 303 mm | 8.2° | 6.9° |
| 50 mm | 433 mm | 5.8° | 4.8° |
| 85 mm | 737 mm | 3.4° | 2.8° |
Multiply by the 8.67× crop factor for the full-frame equivalent field of view.
Milky Way exposure: NPF and 500 rule
| Focal length | NPF @ f/1.8 | NPF @ f/2.8 | Strict NPF @ f/2.8 | 500 rule |
|---|---|---|---|---|
| 8 mm | 16.9 s | 21.2 s | 11.6 s | 7.2 s |
NPF = (35 × f-number + 30 × pixel pitch) ÷ focal length, with a pixel pitch of 2.4 µm (typical for this format — exact resolution not in our database). The strict version (Michaud's detailed NPF for the galactic core) gives pin-point stars at 100% view; the 500 rule is a loose rule of thumb that shows trailing on modern sensors.
How to check the Apple iPhone XS (tele) shutter count
Not every maker writes a shutter count into image files. Try `exiftool -a -G1 -s image` on an unedited original and look for a tag containing "Shutter" or "Count".
ExifTool tag: (varies). Always test an original, unedited file straight from the card.
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