Specifications#
- Brand
- Pentax
- Model
- 645
- Camera type
- Film SLR
- Lens mount
- Sony / Minolta A-mount
- Film format
- 6 × 6 cm film
- Image area
- 56.0 × 56.0 mm (6 × 6 cm film)
- Crop factor
- 0.55×
- Fastest shutter
- 1/1,000 s
- Viewfinder
- fixed eye-level pentaprism
- Focus
- manual (auto on 645N)
- Metering
- TTL center-weighted
- Exposure modes
- automatic, manual
- Shutter
- vertical cloth focal plane
- Flash
- hot shoe, socket, X-sync
- Battery
- 6 AA
- Made in
- Japan
Specifications merged from Wikipedia and Wikidata. Spot an error? Tell us.
Sensor size compared#
Focal length equivalents & field of view#
Multiply any focal length by 0.55 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 | 11 mm | 106.3° | 106.3° | 124.1° |
| 23 mm | 13 mm | 101.2° | 101.2° | 119.7° |
| 28 mm | 15 mm | 90.0° | 90.0° | 109.5° |
| 32 mm | 17 mm | 82.4° | 82.4° | 102.1° |
| 35 mm | 19 mm | 77.3° | 77.3° | 97.1° |
| 45 mm | 25 mm | 63.8° | 63.8° | 82.7° |
| 55 mm | 30 mm | 54.0° | 54.0° | 71.5° |
| 63 mm | 34 mm | 47.9° | 47.9° | 64.3° |
| 80 mm | 44 mm | 38.6° | 38.6° | 52.7° |
| 90 mm | 49 mm | 34.6° | 34.6° | 47.5° |
| 110 mm | 60 mm | 28.6° | 28.6° | 39.6° |
| 120 mm | 66 mm | 26.3° | 26.3° | 36.5° |
| 150 mm | 82 mm | 21.1° | 21.1° | 29.6° |
| 180 mm | 98 mm | 17.7° | 17.7° | 24.8° |
| 250 mm | 137 mm | 12.8° | 12.8° | 18.0° |
| 350 mm | 191 mm | 9.1° | 9.1° | 12.9° |
Depth of field table#
Total depth of field at each subject distance, using a circle of confusion of 54.9 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 |
|---|---|---|---|---|---|---|---|---|
| 40 mm | f/1.8 | 2.8 cm | 11.9 cm | 49.2 cm | 1.14 m | 3.38 m | 19.8 m | 16.2 m |
| 40 mm | f/2.8 | 4.4 cm | 18.6 cm | 78.1 cm | 1.86 m | 6.17 m | 228 m | 10.4 m |
| 40 mm | f/4 | 6.3 cm | 26.8 cm | 1.16 m | 2.92 m | 12.7 m | ∞ | 7.32 m |
| 40 mm | f/8 | 12.8 cm | 56.7 cm | 3.03 m | 14.4 m | ∞ | ∞ | 3.68 m |
| 79 mm | f/1.8 | 0.7 cm | 2.9 cm | 12.2 cm | 27.8 cm | 78.4 cm | 3.22 m | 63.2 m |
| 79 mm | f/2.8 | 1.0 cm | 4.5 cm | 19.0 cm | 43.4 cm | 1.23 m | 5.20 m | 40.7 m |
| 79 mm | f/4 | 1.5 cm | 6.5 cm | 27.2 cm | 62.3 cm | 1.79 m | 7.95 m | 28.5 m |
| 79 mm | f/8 | 3.0 cm | 13.0 cm | 55.1 cm | 1.29 m | 3.94 m | 27.3 m | 14.3 m |
| 134 mm | f/1.8 | 0.2 cm | 1.0 cm | 4.1 cm | 9.5 cm | 26.8 cm | 1.09 m | 182 m |
| 134 mm | f/2.8 | 0.3 cm | 1.5 cm | 6.4 cm | 14.7 cm | 41.7 cm | 1.70 m | 117 m |
| 134 mm | f/4 | 0.4 cm | 2.1 cm | 9.1 cm | 21.1 cm | 59.7 cm | 2.45 m | 81.9 m |
| 134 mm | f/8 | 0.9 cm | 4.2 cm | 18.3 cm | 42.3 cm | 1.21 m | 5.13 m | 41.0 m |
| 221 mm | f/1.8 | 0.1 cm | 0.3 cm | 1.4 cm | 3.4 cm | 9.7 cm | 39.6 cm | 494 m |
| 221 mm | f/2.8 | 0.1 cm | 0.5 cm | 2.2 cm | 5.2 cm | 15.0 cm | 61.6 cm | 318 m |
| 221 mm | f/4 | 0.1 cm | 0.7 cm | 3.2 cm | 7.5 cm | 21.5 cm | 88.1 cm | 223 m |
| 221 mm | f/8 | 0.3 cm | 1.4 cm | 6.4 cm | 15.0 cm | 43.1 cm | 1.77 m | 111 m |
Equivalent aperture#
Exposure is identical at the same f-number on any format; equivalence only describes depth of field and total light.
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. (NPF needs a known resolution and is omitted here.)
| Focal length | 500 rule |
|---|---|
| 26 mm (14 mm eq.) | 35.2 s |
| 37 mm (20 mm eq.) | 24.7 s |
| 44 mm (24 mm eq.) | 20.8 s |
| 64 mm (35 mm eq.) | 14.3 s |
| 92 mm (50 mm eq.) | 9.9 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 |
|---|---|---|---|
| 44 mm | 1/25 s | 0.3 s | 1.3 s |
| 92 mm | 1/50 s | 1/6 s | 0.6 s |
| 183 mm | 1/100 s | 1/13 s | 0.3 s |
| 366 mm | 1/200 s | 1/25 s | 1/6 s |
Lenses for the Pentax 645#
Native Sony / Minolta A-mount lenses in our database (129 total). Also adaptable: T-mount (T2), M42 screw mount, Deckel (DKL), Tamron Adaptall, M39 / LTM (Leica thread).
- Samyang 8mm f/3.5 Fish-Eye CS 8 mm
- Samyang 10mm f/2.8 ED AS NCS CS 10 mm
- Laowa 12mm f/2.8 Zero-D 12 mm
- Samyang 14mm f/2.8 AE ED AS IF UMC 14 mm
- Laowa 15mm F/4 Wide Angle Macro 15 mm
- Samyang 16mm f/2.0 ED AS UMC CS 16 mm
- Samyang 20mm f/1.8 ED AS UMC 20 mm
- Samyang 24mm f/1.4 ED AS IF UMC 24 mm
- Samyang T-S 24mm f/3.5 ED AS UMC 24 mm
- Laowa 60mm f/2.8 2X Ultra-Macro 60 mm
- Samyang 85mm f/1.4 IF UMC Aspherical 85 mm
- Samyang 135mm f/2 ED UMC 135 mm
- Sigma 4.5mm f/2.8 EX DC HSM circular fisheye 4.5 mm
- Sigma 8-16mm f/4.5-5.6 DC HSM 8–16 mm
- Sigma 10-20mm f/3.5 EX DC HSM 10–20 mm
- Sigma 10-20mm f/4-5.6 EX DC 10–20 mm
- Sigma 10mm f/2.8 EX DC Fisheye HSM 10 mm
- Tamron SP AF 10-24mm f/3.5-4.5 Di II LD Aspherical (IF) 10–24 mm
- Tamron SP AF 11-18mm f/4.5-5.6 Di-II LD Aspherical (IF) 11–18 mm
- Tokina AF 11-16mm f/2.8 AT-X Pro DX 11–16 mm
- Tokina AT-X 116 PRO DX II (11-16mm f/2.8) 11–16 mm
- Sigma 12-24mm F4.5-5.6 II DG HSM 12–24 mm
- Sigma 14mm f/2.8 EX 14 mm
- Sigma 14mm f/2.8 EX Aspherical HSM 14 mm
- Sigma 14mm f/3.5 EX 14 mm
- Sigma 15-30mm f/3.5-4.5 EX DG Aspherical 15–30 mm
- Sigma 15mm f/2.8 EX DG Diagonal Fisheye 15 mm
- Tamron SP 15-30mm f/2.8 Di VC USD 15–30 mm
- Sony AF DT 16-105mm f/3.5-5.6 16–105 mm
- Sony DT 16-50mm f/2.8 SSM 16–50 mm
- Sony Zeiss Vario-Sonnar T* 16-35mm f/2.8 ZA SSM II 16–35 mm
- Tamron 16-300mm f/3.5-6.3 Di II VC PZD Macro B016 16–300 mm
- Sigma 17-35mm F2.8-4 EX DG Aspherical HSM 17–35 mm
- Sigma 17-35mm f/2.8-4 EX DG 17–35 mm
- Sigma 17-50mm f/2.8 EX DC OS HSM 17–50 mm
- Sigma 17-70mm f/2.8-4 DC Macro OS HSM | Contemporary 013 17–70 mm
Film stocks for the Pentax 645#
Films currently made in 120 format.
- ADOX CHS 100 II ISO 100
- ADOX CMS 20 II PRO ISO 20
- ADOX HR-50 ISO 50
- Agfa Copex Rapid ISO 50
- Bergger Pancro 400 ISO 400
- CatLABS X FILM 100 Color ISO 100
- CatLABS X FILM 320 Pro ISO 320
- CatLABS X FILM 80 ISO 80
- CineStill 400D ISO 400
- CineStill 50D ISO 50
- CineStill 800T ISO 800
- CineStill Red Rum ISO 200
- CineStill bwXX ISO 250
- FILM Ferrania Orto ISO 50
- FILM Ferrania P30 ISO 80
- Film Photography Project Dracula ISO 64
- Film Photography Project Frankenstein ISO 200
- Film Photography Project THE MUMMY 400 ISO 400
Similar cameras#
Other 6 × 6 cm film film cameras from around the same time.
- Mamiya RB67 1970
- Mamiya C 1956
- Fujifilm GX680
- Pentacon Six 1966
- Voigtländer Brillant 1932
Frequently asked questions#
What is the crop factor of the Pentax 645?
The Pentax 645 has a crop factor of 0.55× relative to 35 mm full frame (diagonal 79.2 mm vs 43.3 mm).
What size is the Pentax 645 frame?
56.0 × 56.0 mm (6 × 6 cm film), an area of 3136 mm² — 363% of full frame.
What lens mount does the Pentax 645 use?
The Pentax 645 uses the Sony / Minolta A-mount (flange distance 44.50 mm).
How long can I expose the night sky with the Pentax 645?
With a 37 mm lens (20 mm equivalent) the 500 rule gives 25 s.
Sources & licences#
- Wikipedia: Pentax 645 — CC BY-SA 4.0
- Wikidata Q4046598 — CC0
Last updated October 03, 2026 · How we calculate · Sources