Specifications#
- Brand
- Pentax
- Model
- 645Z
- Camera type
- DSLR
- Lens mount
- Pentax 645
- Sensor size
- 44.0 × 33.0 mm (Medium format 44 × 33 mm)
- Crop factor
- 0.79×
- Resolution
- 51 MP (8,256 × 6,192 px)
- Fastest shutter
- 1/4,000 s
- Continuous shooting
- 3 fps
- Weight
- 1,550 g (54.7 oz)
- Sensor type
- CMOS
- AF points / area
- 27 focus points
- Dimensions
- 156 x 117 x 123mm (6.14 x 4.61 x 4.84 inches)
- Drive
- 3 frames per second
Specifications merged from Wikipedia, Wikidata, Lensfun and openMVG. Spot an error? Tell us.
Sensor size compared#
Focal length equivalents & field of view#
Multiply any focal length by 0.79 to get the full-frame field of view. Angles are for a rectilinear lens focused at infinity.
| Lens on this camera | Full-frame equivalent | Horizontal | Vertical | Diagonal |
|---|---|---|---|---|
| 21 mm | 17 mm | 92.7° | 76.3° | 105.3° |
| 23 mm | 18 mm | 87.5° | 71.3° | 100.2° |
| 28 mm | 22 mm | 76.3° | 61.0° | 89.0° |
| 32 mm | 25 mm | 69.0° | 54.6° | 81.3° |
| 35 mm | 28 mm | 64.3° | 50.5° | 76.3° |
| 45 mm | 35 mm | 52.1° | 40.3° | 62.9° |
| 55 mm | 43 mm | 43.6° | 33.4° | 53.1° |
| 63 mm | 50 mm | 38.5° | 29.4° | 47.2° |
| 80 mm | 63 mm | 30.8° | 23.3° | 37.9° |
| 90 mm | 71 mm | 27.5° | 20.8° | 34.0° |
| 110 mm | 87 mm | 22.6° | 17.1° | 28.1° |
| 120 mm | 94 mm | 20.8° | 15.7° | 25.8° |
| 150 mm | 118 mm | 16.7° | 12.6° | 20.8° |
| 180 mm | 142 mm | 13.9° | 10.5° | 17.4° |
| 250 mm | 197 mm | 10.1° | 7.6° | 12.6° |
| 350 mm | 275 mm | 7.2° | 5.4° | 9.0° |
Depth of field table#
Total depth of field at each subject distance, using a circle of confusion of 38.1 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 |
|---|---|---|---|---|---|---|---|---|
| 28 mm | f/1.8 | 4.1 cm | 17.1 cm | 71.2 cm | 1.67 m | 5.37 m | 73.5 m | 11.4 m |
| 28 mm | f/2.8 | 6.5 cm | 26.9 cm | 1.16 m | 2.90 m | 12.5 m | ∞ | 7.37 m |
| 28 mm | f/4 | 9.3 cm | 39.2 cm | 1.80 m | 5.21 m | 151 m | ∞ | 5.17 m |
| 28 mm | f/8 | 19.0 cm | 88.3 cm | 7.47 m | ∞ | ∞ | ∞ | 2.60 m |
| 55 mm | f/1.8 | 1.0 cm | 4.3 cm | 17.7 cm | 40.3 cm | 1.14 m | 4.76 m | 44.1 m |
| 55 mm | f/2.8 | 1.6 cm | 6.7 cm | 27.6 cm | 63.1 cm | 1.80 m | 8.01 m | 28.4 m |
| 55 mm | f/4 | 2.2 cm | 9.6 cm | 39.6 cm | 91.1 cm | 2.66 m | 13.4 m | 19.9 m |
| 55 mm | f/8 | 4.5 cm | 19.2 cm | 81.6 cm | 1.95 m | 6.64 m | ∞ | 9.97 m |
| 94 mm | f/1.8 | 0.3 cm | 1.4 cm | 5.9 cm | 13.6 cm | 38.2 cm | 1.55 m | 129 m |
| 94 mm | f/2.8 | 0.5 cm | 2.2 cm | 9.2 cm | 21.1 cm | 59.5 cm | 2.43 m | 82.8 m |
| 94 mm | f/4 | 0.7 cm | 3.1 cm | 13.2 cm | 30.2 cm | 85.3 cm | 3.52 m | 58.0 m |
| 94 mm | f/8 | 1.4 cm | 6.3 cm | 26.4 cm | 60.8 cm | 1.74 m | 7.75 m | 29.1 m |
| 154 mm | f/1.8 | 0.1 cm | 0.5 cm | 2.1 cm | 4.9 cm | 14.0 cm | 57.0 cm | 346 m |
| 154 mm | f/2.8 | 0.2 cm | 0.8 cm | 3.3 cm | 7.7 cm | 21.8 cm | 88.8 cm | 222 m |
| 154 mm | f/4 | 0.2 cm | 1.1 cm | 4.8 cm | 11.0 cm | 31.2 cm | 1.27 m | 156 m |
| 154 mm | f/8 | 0.4 cm | 2.2 cm | 9.5 cm | 22.0 cm | 62.6 cm | 2.57 m | 77.9 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 5.33 µm pixels, diffraction starts to soften pixel-level detail around f/7.9. For maximum sharpness keep landscapes between f/4.4 and f/8; stopping down further trades detail for depth of field.
| Aperture | Airy disk diameter | Spread over | At 100% view |
|---|---|---|---|
| f/2.8 | 3.8 µm | 0.7 px | sharp |
| f/4 | 5.4 µm | 1.0 px | sharp |
| f/5.6 | 7.5 µm | 1.4 px | sharp |
| f/8 | 10.7 µm | 2.0 px | slight softening |
| f/11 | 14.8 µm | 2.8 px | slight softening |
| f/16 | 21.5 µm | 4.0 px | visibly soft |
| f/22 | 29.5 µm | 5.5 px | visibly soft |
Maximum print sizes#
At 51 MP the Pentax 645Z produces 8,256 × 6,192 pixel images. See the 50 megapixel guide or the print size calculator.
| Resolution | Typical use | Inches | Centimetres |
|---|---|---|---|
| 300 DPI | Photo-lab quality | 27.5 × 20.6 in | 70 × 52 cm |
| 240 DPI | Fine-art inkjet | 34.4 × 25.8 in | 87 × 66 cm |
| 200 DPI | Wall print | 41.3 × 31.0 in | 105 × 79 cm |
| 150 DPI | Poster, viewed from 1 m+ | 55.0 × 41.3 in | 140 × 105 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 |
|---|---|---|---|---|
| 18 mm (14 mm eq.) | 35.3 s | 12.4 s | 14.3 s | 16.7 s |
| 25 mm (20 mm eq.) | 25.4 s | 8.9 s | 10.3 s | 12.0 s |
| 31 mm (24 mm eq.) | 20.5 s | 7.2 s | 8.3 s | 9.7 s |
| 44 mm (35 mm eq.) | 14.4 s | 5.1 s | 5.9 s | 6.8 s |
| 64 mm (50 mm eq.) | 9.9 s | 3.5 s | 4.0 s | 4.7 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 |
|---|---|---|---|
| 31 mm | 1/25 s | 0.3 s | 1.3 s |
| 64 mm | 1/50 s | 1/6 s | 0.6 s |
| 127 mm | 1/100 s | 1/13 s | 0.3 s |
| 254 mm | 1/200 s | 1/25 s | 1/6 s |
Similar cameras#
Other Medium format 44 × 33 mm cameras from around the same time.
Frequently asked questions#
What is the crop factor of the Pentax 645Z?
The Pentax 645Z has a crop factor of 0.79× relative to 35 mm full frame (diagonal 55.0 mm vs 43.3 mm).
What size is the Pentax 645Z sensor?
44.0 × 33.0 mm (Medium format 44 × 33 mm), an area of 1452 mm² — 168% of full frame.
Is the Pentax 645Z full frame?
No — its sensor is larger than full frame (medium format).
How many megapixels does the Pentax 645Z have?
51 megapixels (8,256 × 6,192 pixels), enough for a 28 × 21 inch print at 300 DPI.
What lens mount does the Pentax 645Z use?
The Pentax 645Z uses the Pentax 645 (flange distance 70.87 mm).
How long can I expose the night sky with the Pentax 645Z?
With a 25 mm lens (20 mm equivalent) the 500 rule gives 25 s and the stricter NPF rule at f/2.8 gives 10 s.
Sources & licences#
- Wikipedia: Pentax 645Z — CC BY-SA 4.0
- Wikidata Q17636519 — CC0
- Lensfun camera database — CC BY-SA 3.0
- openMVG sensor width database — MPL-2.0
Last updated October 03, 2026 · How we calculate · Sources