The Sony Alpha 7R III uses the Sony E mount with a 1.00× crop factor (about 36.0 × 24.0 mm sensor), 42.4 megapixels, announced in 2017. Below: equivalent focal lengths, maximum shutter speeds for sharp stars, a hyperfocal distance chart, compatible lenses and how to check the shutter count.
Equivalent focal length & field of view
| Lens focal length | Full-frame equivalent | Diagonal FOV | Horizontal FOV |
|---|---|---|---|
| 10 mm | 10 mm | 130.4° | 121.9° |
| 12 mm | 12 mm | 122.0° | 112.6° |
| 14 mm | 14 mm | 114.2° | 104.3° |
| 16 mm | 16 mm | 107.0° | 96.7° |
| 18 mm | 18 mm | 100.5° | 90.0° |
| 20 mm | 20 mm | 94.5° | 84.0° |
| 24 mm | 24 mm | 84.1° | 73.7° |
| 28 mm | 28 mm | 75.4° | 65.5° |
| 35 mm | 35 mm | 63.4° | 54.4° |
| 50 mm | 50 mm | 46.8° | 39.6° |
| 85 mm | 85 mm | 28.6° | 23.9° |
| 135 mm | 135 mm | 18.2° | 15.2° |
| 200 mm | 200 mm | 12.3° | 10.3° |
| 300 mm | 300 mm | 8.2° | 6.9° |
| 400 mm | 400 mm | 6.2° | 5.2° |
| 600 mm | 600 mm | 4.1° | 3.4° |
Multiply by the 1.00× 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 |
|---|---|---|---|---|
| 10 mm | 19.8 s | 23.3 s | 12.6 s | 50.0 s |
| 12 mm | 16.5 s | 19.4 s | 10.5 s | 41.7 s |
| 14 mm | 14.2 s | 16.7 s | 9.0 s | 35.7 s |
| 16 mm | 12.4 s | 14.6 s | 7.9 s | 31.2 s |
| 18 mm | 11.0 s | 13.0 s | 7.0 s | 27.8 s |
| 20 mm | 9.9 s | 11.7 s | 6.3 s | 25.0 s |
| 24 mm | 8.3 s | 9.7 s | 5.3 s | 20.8 s |
| 28 mm | 7.1 s | 8.3 s | 4.6 s | 17.9 s |
| 35 mm | 5.7 s | 6.7 s | 3.7 s | 14.3 s |
| 50 mm | 4.0 s | 4.7 s | 2.6 s | 10.0 s |
NPF = (35 × f-number + 30 × pixel pitch) ÷ focal length, with a pixel pitch of 4.51 µm (from 42.4 MP). 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.
Hyperfocal distance chart
| Focal length | f/2.8 | f/5.6 | f/8 | f/11 | f/16 |
|---|---|---|---|---|---|
| 14 mm | 2.3 m | 1.2 m | 0.8 m | 0.6 m | 0.4 m |
| 16 mm | 3.1 m | 1.5 m | 1.1 m | 0.8 m | 0.5 m |
| 18 mm | 3.9 m | 1.9 m | 1.4 m | 1.0 m | 0.7 m |
| 20 mm | 4.8 m | 2.4 m | 1.7 m | 1.2 m | 0.9 m |
| 24 mm | 6.9 m | 3.5 m | 2.4 m | 1.8 m | 1.2 m |
| 28 mm | 9.4 m | 4.7 m | 3.3 m | 2.4 m | 1.7 m |
| 35 mm | 15 m | 7.3 m | 5.1 m | 3.7 m | 2.6 m |
| 50 mm | 30 m | 15 m | 10 m | 7.6 m | 5.3 m |
Focus at the hyperfocal distance and everything from half that distance to infinity is acceptably sharp (circle of confusion 0.03 mm). Use the hyperfocal calculator for other settings.
Maximum print size
| Print resolution | Inches | Centimeters |
|---|---|---|
| 150 ppi | 53.2 × 35.4 in | 135 × 90 cm |
| 200 ppi | 39.9 × 26.6 in | 101 × 68 cm |
| 240 ppi | 33.2 × 22.1 in | 84 × 56 cm |
| 300 ppi | 26.6 × 17.7 in | 68 × 45 cm |
300 ppi suits close viewing; 150–200 ppi is plenty for large prints viewed from a distance.
Compatible lenses (207 in our database)
Native and adapter-free compatible lenses from the Lensfun database. Third-party and adapted lenses may also work.
How to check the Sony Alpha 7R III shutter count
Most Sony Alpha bodies record the count in MakerNotes. Use `exiftool -ShutterCount -ShutterCount2 image.arw` on an unedited file.
ExifTool tag: ShutterCount / ShutterCount2. Always test an original, unedited file straight from the card.
Where to buy
Compare new and used prices at these retailers:
B&H PhotoAmazonKEH (used)MPB (used)Other Sony E cameras
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