Specifications#
- Brand
- Pentax
- Model
- Optio S50
- Camera type
- Compact
- Sensor size
- 5.7 × 4.3 mm (1/2.5" sensor)
- Crop factor
- 6.03×
- Resolution
- 5 MP (2,560 × 1,920 px)
- Fastest shutter
- 1/2,000 s
- Weight
- 180 g (6.3 oz)
- Sensor type
- CCD
- Dimensions
- 89 x 59 x 26mm (3.5 x 2.32 x 1.02 inches)
- Lens
- 36-107mm equivalent
Specifications merged from Wikipedia, Wikidata and openMVG. Spot an error? Tell us.
Sensor size compared#
Focal length equivalents & field of view#
Multiply any focal length by 6.03 to get the full-frame field of view. For fixed-lens cameras use the real focal length printed on the lens (e.g. “6.1–18.3 mm”), not the 35 mm equivalent.
| Lens on this camera | Full-frame equivalent | Horizontal | Vertical | Diagonal |
|---|---|---|---|---|
| 4 mm | 24 mm | 71.3° | 56.6° | 83.8° |
| 4.5 mm | 27 mm | 65.1° | 51.2° | 77.1° |
| 5 mm | 30 mm | 59.7° | 46.6° | 71.3° |
| 6 mm | 36 mm | 51.1° | 39.5° | 61.8° |
| 8 mm | 48 mm | 39.5° | 30.2° | 48.3° |
| 10 mm | 60 mm | 32.0° | 24.3° | 39.5° |
| 12 mm | 72 mm | 26.9° | 20.4° | 33.3° |
| 15 mm | 90 mm | 21.7° | 16.4° | 26.9° |
| 20 mm | 121 mm | 16.3° | 12.3° | 20.3° |
| 25 mm | 151 mm | 13.1° | 9.9° | 16.3° |
| 30 mm | 181 mm | 10.9° | 8.2° | 13.6° |
| 40 mm | 241 mm | 8.2° | 6.2° | 10.3° |
| 50 mm | 301 mm | 6.6° | 4.9° | 8.2° |
| 70 mm | 422 mm | 4.7° | 3.5° | 5.9° |
| 100 mm | 603 mm | 3.3° | 2.5° | 4.1° |
| 150 mm | 904 mm | 2.2° | 1.6° | 2.7° |
Depth of field table#
Total depth of field at each subject distance, using a circle of confusion of 5.0 µm (the 0.030 mm full-frame standard scaled by the crop factor).
| Focal | Aperture | 50.0 cm | 1.00 m | 2.00 m | 3.00 m | 5.00 m | 10.0 m | Hyperfocal |
|---|---|---|---|---|---|---|---|---|
| 4 mm | f/2 | 34.1 cm | 2.01 m | ∞ | ∞ | ∞ | ∞ | 1.61 m |
| 4 mm | f/2.8 | 53.1 cm | 7.01 m | ∞ | ∞ | ∞ | ∞ | 1.15 m |
| 4 mm | f/4 | 99.7 cm | ∞ | ∞ | ∞ | ∞ | ∞ | 80.8 cm |
| 4 mm | f/8 | ∞ | ∞ | ∞ | ∞ | ∞ | ∞ | 40.6 cm |
| 7 mm | f/2 | 10.1 cm | 42.1 cm | 1.94 m | 5.79 m | ∞ | ∞ | 4.93 m |
| 7 mm | f/2.8 | 14.3 cm | 61.4 cm | 3.34 m | 18.5 m | ∞ | ∞ | 3.52 m |
| 7 mm | f/4 | 20.9 cm | 96.4 cm | 9.41 m | ∞ | ∞ | ∞ | 2.47 m |
| 7 mm | f/8 | 47.7 cm | 4.62 m | ∞ | ∞ | ∞ | ∞ | 1.24 m |
| 12 mm | f/2 | 3.4 cm | 13.7 cm | 56.0 cm | 1.29 m | 3.91 m | 26.4 m | 14.5 m |
| 12 mm | f/2.8 | 4.7 cm | 19.3 cm | 79.9 cm | 1.89 m | 6.29 m | 294 m | 10.3 m |
| 12 mm | f/4 | 6.8 cm | 27.8 cm | 1.19 m | 2.99 m | 13.1 m | ∞ | 7.25 m |
| 12 mm | f/8 | 13.7 cm | 59.0 cm | 3.15 m | 15.6 m | ∞ | ∞ | 3.63 m |
| 20 mm | f/2 | 1.2 cm | 4.9 cm | 19.8 cm | 44.7 cm | 1.26 m | 5.29 m | 40.2 m |
| 20 mm | f/2.8 | 1.7 cm | 6.8 cm | 27.7 cm | 63.0 cm | 1.79 m | 7.91 m | 28.7 m |
| 20 mm | f/4 | 2.4 cm | 9.8 cm | 39.8 cm | 91.0 cm | 2.64 m | 13.2 m | 20.1 m |
| 20 mm | f/8 | 4.8 cm | 19.7 cm | 82.0 cm | 1.95 m | 6.57 m | 1.5 km | 10.1 m |
Equivalent aperture#
Exposure is identical at the same f-number on any format; equivalence only describes depth of field and total light.
Diffraction & pixel pitch#
With 2.24 µm pixels, diffraction starts to soften pixel-level detail around f/3.3. For maximum sharpness keep landscapes between f/2.8 and f/3; stopping down further trades detail for depth of field.
| Aperture | Airy disk diameter | Spread over | At 100% view |
|---|---|---|---|
| f/2.8 | 3.8 µm | 1.7 px | sharp |
| f/4 | 5.4 µm | 2.4 px | slight softening |
| f/5.6 | 7.5 µm | 3.4 px | visibly soft |
| f/8 | 10.7 µm | 4.8 px | visibly soft |
| f/11 | 14.8 µm | 6.6 px | visibly soft |
| f/16 | 21.5 µm | 9.6 px | visibly soft |
| f/22 | 29.5 µm | 13.2 px | visibly soft |
Maximum print sizes#
At 5 MP the Pentax Optio S50 produces 2,560 × 1,920 pixel images. See the 5 megapixel guide or the print size calculator.
| Resolution | Typical use | Inches | Centimetres |
|---|---|---|---|
| 300 DPI | Photo-lab quality | 8.5 × 6.4 in | 22 × 16 cm |
| 240 DPI | Fine-art inkjet | 10.7 × 8.0 in | 27 × 20 cm |
| 200 DPI | Wall print | 12.8 × 9.6 in | 33 × 24 cm |
| 150 DPI | Poster, viewed from 1 m+ | 17.1 × 12.8 in | 43 × 33 cm |
Night-sky exposure limits#
Longest exposure before stars trail. The NPF rule accounts for pixel pitch and is stricter than the classic 500 rule — use it for pin-sharp stars on high-resolution sensors.
| Focal length | 500 rule | NPF f/1.8 | NPF f/2.8 | NPF f/4 |
|---|---|---|---|---|
| 4 mm (24 mm eq.) | 20.7 s | 32.6 s | 41.3 s | 51.8 s |
| 5 mm (30 mm eq.) | 16.6 s | 26.1 s | 33.1 s | 41.5 s |
| 6 mm (36 mm eq.) | 13.8 s | 21.7 s | 27.5 s | 34.5 s |
| 7 mm (42 mm eq.) | 11.9 s | 18.6 s | 23.6 s | 29.6 s |
| 8 mm (48 mm eq.) | 10.4 s | 16.3 s | 20.7 s | 25.9 s |
Handheld shutter speed guide#
The reciprocal rule uses the equivalent focal length. High-resolution sensors may need one stop faster than this for pixel-sharp results.
| Focal length | No stabilisation (1/equiv. focal) | With 3-stop IS | With 5-stop IBIS |
|---|---|---|---|
| 4 mm | 1/25 s | 0.3 s | 1.3 s |
| 8 mm | 1/50 s | 1/6 s | 0.6 s |
| 17 mm | 1/100 s | 1/13 s | 0.3 s |
| 33 mm | 1/200 s | 1/25 s | 1/6 s |
Lens#
The Pentax Optio S50 has a built-in, non-interchangeable lens. Use the real focal length of that lens with the tables above; its full-frame equivalent is that number × 6.03.
Similar cameras#
Other 1/2.5" cameras from around the same time.
Frequently asked questions#
What is the crop factor of the Pentax Optio S50?
The Pentax Optio S50 has a crop factor of 6.03× relative to 35 mm full frame (diagonal 7.2 mm vs 43.3 mm).
What size is the Pentax Optio S50 sensor?
5.7 × 4.3 mm (1/2.5"), an area of 25 mm² — 3% of full frame.
Is the Pentax Optio S50 full frame?
No — its sensor is 1/2.5", which is 34.9× smaller in area than full frame.
How many megapixels does the Pentax Optio S50 have?
5 megapixels (2,560 × 1,920 pixels), enough for a 9 × 6 inch print at 300 DPI.
How long can I expose the night sky with the Pentax Optio S50?
With a 5 mm lens (30 mm equivalent) the 500 rule gives 17 s and the stricter NPF rule at f/2.8 gives 33 s.
Sources & licences#
- Wikipedia: Pentax Optio S50 — CC BY-SA 4.0
- Wikidata Q2069381 — CC0
- openMVG sensor width database — MPL-2.0
Last updated October 03, 2026 · How we calculate · Sources