Specifications#
- Brand
- Pentax
- Model
- K100D
- Camera type
- DSLR
- Released
- 2006-01-01
- Lens mount
- Pentax K
- Sensor size
- 23.5 × 15.7 mm (APS-C)
- Crop factor
- 1.53×
- Resolution
- 6 MP (3,008 × 2,000 px)
- Weight
- 565 g (19.9 oz)
- Sensor
- APS-C (23.5 x 15.7 mm) Interline interlace CCD with a primary color filter
- Metering
- TTL open-aperture metering with choice of: 16-segment, Center-weighted & Spot meter
- Exposure modes
- Program, Shutter-Speed Priority, Aperture Priority, Manual, Bulb, Auto, Picture modes (Standard, Portrait, Landscape, Macro, Action, Night scene portrait, Standard flash-off)
- Battery
- AA (×4) or CR-V3 (×2), Optional AC adapter
- Lens
- Interchangeable Pentax KAF2 mount compatible with Pentax auto-aperture lenses; older lenses supported in stop-down metering mode (using the AE/L function).
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 1.53 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 |
|---|---|---|---|---|
| 8 mm | 12 mm | 111.5° | 88.9° | 121.0° |
| 10 mm | 15 mm | 99.2° | 76.3° | 109.4° |
| 12 mm | 18 mm | 88.8° | 66.4° | 99.3° |
| 14 mm | 21 mm | 80.0° | 58.6° | 90.5° |
| 16 mm | 24 mm | 72.6° | 52.3° | 82.9° |
| 18 mm | 28 mm | 66.3° | 47.1° | 76.3° |
| 20 mm | 31 mm | 60.9° | 42.9° | 70.5° |
| 24 mm | 37 mm | 52.2° | 36.2° | 61.0° |
| 28 mm | 43 mm | 45.5° | 31.3° | 53.6° |
| 35 mm | 54 mm | 37.1° | 25.3° | 44.0° |
| 40 mm | 61 mm | 32.7° | 22.2° | 38.9° |
| 50 mm | 77 mm | 26.4° | 17.8° | 31.6° |
| 56 mm | 86 mm | 23.7° | 16.0° | 28.3° |
| 70 mm | 107 mm | 19.1° | 12.8° | 22.8° |
| 85 mm | 130 mm | 15.7° | 10.6° | 18.9° |
| 100 mm | 153 mm | 13.4° | 9.0° | 16.1° |
| 135 mm | 207 mm | 9.9° | 6.7° | 12.0° |
| 200 mm | 306 mm | 6.7° | 4.5° | 8.1° |
| 300 mm | 459 mm | 4.5° | 3.0° | 5.4° |
| 400 mm | 612 mm | 3.4° | 2.2° | 4.0° |
| 600 mm | 919 mm | 2.2° | 1.5° | 2.7° |
| 800 mm | 1225 mm | 1.7° | 1.1° | 2.0° |
Depth of field table#
Total depth of field at each subject distance, using a circle of confusion of 19.6 µm (the 0.030 mm full-frame standard scaled by the crop factor). Detailed tables: 24 mm f/1.8, 24 mm f/2.8, 35 mm f/1.8, 35 mm f/2.8, 50 mm f/1.8, 50 mm f/2.8.
| Focal | Aperture | 50.0 cm | 1.00 m | 2.00 m | 3.00 m | 5.00 m | 10.0 m | Hyperfocal |
|---|---|---|---|---|---|---|---|---|
| 14 mm | f/1.8 | 8.8 cm | 36.6 cm | 1.64 m | 4.53 m | 46.1 m | ∞ | 5.57 m |
| 14 mm | f/2.8 | 13.9 cm | 59.8 cm | 3.22 m | 16.6 m | ∞ | ∞ | 3.59 m |
| 14 mm | f/4 | 20.2 cm | 93.4 cm | 8.61 m | ∞ | ∞ | ∞ | 2.51 m |
| 14 mm | f/8 | 45.8 cm | 4.17 m | ∞ | ∞ | ∞ | ∞ | 1.26 m |
| 28 mm | f/1.8 | 2.1 cm | 8.8 cm | 35.8 cm | 81.7 cm | 2.35 m | 11.2 m | 22.3 m |
| 28 mm | f/2.8 | 3.3 cm | 13.7 cm | 56.3 cm | 1.30 m | 3.96 m | 27.2 m | 14.3 m |
| 28 mm | f/4 | 4.7 cm | 19.6 cm | 82.1 cm | 1.96 m | 6.60 m | 3.3 km | 10.0 m |
| 28 mm | f/8 | 9.5 cm | 40.4 cm | 1.87 m | 5.51 m | 860 m | ∞ | 5.03 m |
| 48 mm | f/1.8 | 0.7 cm | 2.9 cm | 12.0 cm | 27.2 cm | 76.3 cm | 3.12 m | 65.4 m |
| 48 mm | f/2.8 | 1.1 cm | 4.5 cm | 18.6 cm | 42.4 cm | 1.20 m | 5.02 m | 42.0 m |
| 48 mm | f/4 | 1.5 cm | 6.5 cm | 26.7 cm | 60.9 cm | 1.73 m | 7.65 m | 29.4 m |
| 48 mm | f/8 | 3.1 cm | 13.0 cm | 54.1 cm | 1.26 m | 3.80 m | 25.0 m | 14.7 m |
| 78 mm | f/1.8 | 0.2 cm | 1.1 cm | 4.5 cm | 10.2 cm | 28.6 cm | 1.15 m | 173 m |
| 78 mm | f/2.8 | 0.4 cm | 1.7 cm | 6.9 cm | 15.8 cm | 44.5 cm | 1.80 m | 111 m |
| 78 mm | f/4 | 0.5 cm | 2.4 cm | 9.9 cm | 22.6 cm | 63.7 cm | 2.60 m | 77.7 m |
| 78 mm | f/8 | 1.1 cm | 4.8 cm | 19.9 cm | 45.4 cm | 1.29 m | 5.47 m | 38.9 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 7.81 µm pixels, diffraction starts to soften pixel-level detail around f/11.6. For maximum sharpness keep landscapes between f/6.4 and f/12; stopping down further trades detail for depth of field.
| Aperture | Airy disk diameter | Spread over | At 100% view |
|---|---|---|---|
| f/2.8 | 3.8 µm | 0.5 px | sharp |
| f/4 | 5.4 µm | 0.7 px | sharp |
| f/5.6 | 7.5 µm | 1.0 px | sharp |
| f/8 | 10.7 µm | 1.4 px | sharp |
| f/11 | 14.8 µm | 1.9 px | sharp |
| f/16 | 21.5 µm | 2.7 px | slight softening |
| f/22 | 29.5 µm | 3.8 px | visibly soft |
Maximum print sizes#
At 6 MP the Pentax K100D produces 3,008 × 2,000 pixel images. See the 6 megapixel guide or the print size calculator.
| Resolution | Typical use | Inches | Centimetres |
|---|---|---|---|
| 300 DPI | Photo-lab quality | 10.0 × 6.7 in | 25 × 17 cm |
| 240 DPI | Fine-art inkjet | 12.5 × 8.3 in | 32 × 21 cm |
| 200 DPI | Wall print | 15.0 × 10.0 in | 38 × 25 cm |
| 150 DPI | Poster, viewed from 1 m+ | 20.1 × 13.3 in | 51 × 34 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 |
|---|---|---|---|---|
| 9 mm (14 mm eq.) | 36.3 s | 33.0 s | 36.9 s | 41.6 s |
| 13 mm (20 mm eq.) | 25.1 s | 22.9 s | 25.6 s | 28.8 s |
| 16 mm (24 mm eq.) | 20.4 s | 18.6 s | 20.8 s | 23.4 s |
| 23 mm (35 mm eq.) | 14.2 s | 12.9 s | 14.5 s | 16.3 s |
| 33 mm (51 mm eq.) | 9.9 s | 9.0 s | 10.1 s | 11.3 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 |
|---|---|---|---|
| 16 mm | 1/25 s | 0.3 s | 1.3 s |
| 33 mm | 1/50 s | 1/6 s | 0.6 s |
| 65 mm | 1/100 s | 1/13 s | 0.3 s |
| 131 mm | 1/200 s | 1/25 s | 1/6 s |
Lenses for the Pentax K100D#
Native Pentax K lenses in our database (170 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
- Pentax smc Pentax-DA Fish-Eye 10-17mm f/3.5-4.5 ED IF 10–17 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
- Pentax HD Pentax-DA* 11-18mm f/2.8 ED DC AW 11–18 mm
- Tamron SP AF 11-18mm f/4.5-5.6 Di-II LD Aspherical (IF) 11–18 mm
- Pentax smc Pentax-DA 12-24mm f/4 ED AL IF 12–24 mm
- Sigma 12-24mm F4.5-5.6 II DG HSM 12–24 mm
- Sigma 12-24mm f/4.5-5.6 EX DG Aspherical HSM 12–24 mm
- Pentax smc PENTAX-DA 14mm F2.8 ED[IF] 14 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
- Pentax HD Pentax-D FA 15-30mm f/2.8 ED SDM WR 15–30 mm
- Pentax smc Pentax-DA 15mm f/4 ED AL Limited 15 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
- Pentax HD Pentax DA* 16-50mm f/2.8 ED PLM AW 16–50 mm
- Pentax HD Pentax-DA 16-85mm f/3.5-5.6 ED DC WR 16–85 mm
- Pentax smc Pentax-DA 16-45mm f/4 ED AL 16–45 mm
- Pentax smc Pentax-DA* 16-50mm f/2.8 ED AL IF SDM 16–50 mm
Similar cameras#
Other APS-C cameras from around the same time.
- Nikon D40 2006
- Nikon D60 2008
- Nikon D80 2006
- Sony Alpha 100 2006
- Nikon D300 2007
- Sony Alpha 700 2007
- Konica Minolta Maxxum 5D 2005
- Nikon D200 2005
- Nikon D50 2005
- Nikon D90 2008
- Sony Alpha 200 2008
- Sony Alpha 350 2008
Frequently asked questions#
What is the crop factor of the Pentax K100D?
The Pentax K100D has a crop factor of 1.53× relative to 35 mm full frame (diagonal 28.3 mm vs 43.3 mm).
What size is the Pentax K100D sensor?
23.5 × 15.7 mm (APS-C), an area of 369 mm² — 43% of full frame.
Is the Pentax K100D full frame?
No — its sensor is APS-C, which is 2.3× smaller in area than full frame.
How many megapixels does the Pentax K100D have?
6 megapixels (3,008 × 2,000 pixels), enough for a 10 × 7 inch print at 300 DPI.
What lens mount does the Pentax K100D use?
The Pentax K100D uses the Pentax K (flange distance 45.46 mm).
How long can I expose the night sky with the Pentax K100D?
With a 13 mm lens (20 mm equivalent) the 500 rule gives 25 s and the stricter NPF rule at f/2.8 gives 26 s.
Sources & licences#
- Wikipedia: Pentax K100D — CC BY-SA 4.0
- Wikidata Q906317 — 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