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Samsung GX-1S

Samsung · Pentax KAF2 · 1.53× crop

The Samsung GX-1S uses the Pentax KAF2 mount with a 1.53× crop factor (about 23.5 × 15.7 mm sensor). Below: equivalent focal lengths, maximum shutter speeds for sharp stars, a hyperfocal distance chart, compatible lenses and how to check the shutter count.

Mount
Pentax KAF2
Crop factor
1.53×
Sensor (approx.)
23.5 × 15.7 mm
Circle of confusion
0.0196 mm

Equivalent focal length & field of view

Lens focal lengthFull-frame equivalentDiagonal FOVHorizontal FOV
8 mm12 mm121.0°111.5°
10 mm15 mm109.4°99.2°
12 mm18 mm99.3°88.8°
14 mm21 mm90.5°80.0°
16 mm24 mm82.9°72.6°
18 mm28 mm76.3°66.3°
20 mm31 mm70.5°60.9°
24 mm37 mm61.0°52.2°
28 mm43 mm53.6°45.5°
35 mm54 mm44.0°37.1°
50 mm77 mm31.6°26.4°
85 mm130 mm18.9°15.7°
135 mm207 mm12.0°9.9°
200 mm306 mm8.1°6.7°
300 mm459 mm5.4°4.5°
400 mm612 mm4.0°3.4°

Multiply by the 1.53× crop factor for the full-frame equivalent field of view.

Milky Way exposure: NPF and 500 rule

Focal lengthNPF @ f/1.8NPF @ f/2.8Strict NPF @ f/2.8500 rule
8 mm22.5 s26.9 s14.5 s40.8 s
10 mm18.0 s21.5 s11.6 s32.7 s
12 mm15.0 s17.9 s9.7 s27.2 s
14 mm12.9 s15.4 s8.3 s23.3 s
16 mm11.2 s13.4 s7.3 s20.4 s
18 mm10.0 s11.9 s6.5 s18.1 s
20 mm9.0 s10.8 s5.9 s16.3 s
24 mm7.5 s9.0 s4.9 s13.6 s
28 mm6.4 s7.7 s4.2 s11.7 s
35 mm5.1 s6.1 s3.4 s9.3 s

NPF = (35 × f-number + 30 × pixel pitch) ÷ focal length, with a pixel pitch of 3.9 µm (typical for this format — exact resolution not in our database). 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 lengthf/2.8f/5.6f/8f/11f/16
10 mm1.8 m0.9 m0.6 m0.5 m0.3 m
14 mm3.6 m1.8 m1.3 m0.9 m0.6 m
16 mm4.7 m2.3 m1.6 m1.2 m0.8 m
18 mm5.9 m3.0 m2.1 m1.5 m1.1 m
20 mm7.3 m3.7 m2.6 m1.9 m1.3 m
24 mm11 m5.3 m3.7 m2.7 m1.9 m
28 mm14 m7.2 m5.0 m3.7 m2.5 m
35 mm22 m11 m7.8 m5.7 m3.9 m
50 mm46 m23 m16 m12 m8.0 m

Focus at the hyperfocal distance and everything from half that distance to infinity is acceptably sharp (circle of confusion 0.0196 mm). Use the hyperfocal calculator for other settings.

Compatible lenses (190 in our database)

LensFocal lengthMax apertureMount
Sigma 4.5mm f/2.8 EX DC HSM circular fisheye4 mmf/2.8Canon EF, Nikon F AF
Samyang 8mm f/3.5 Fish-Eye CS8 mmf/3.5Pentax KAF, Canon EF
Sigma 8-16mm f/4.5-5.6 DC HSM8–16 mmf/4.5Sigma SA, Canon EF
Samyang 10mm f/2.8 ED AS NCS CS10 mmf/2.8Canon EF, Canon EF-M
Sigma 10-20mm f/3.5 EX DC HSM10–20 mmf/3.5Nikon F AF, Sigma SA
Tamron SP AF 10-24mm f/3.5-4.5 Di II LD Aspherical (IF)10–24 mmf/10Canon EF, Nikon F AF
Pentax smc Pentax-DA Fish-Eye 10-17mm f/3.5-4.5 ED IF10–17 mmf/3.5Pentax KAF2
Sigma 10-20mm f/4-5.6 EX DC10–20 mmf/4Nikon F AF, Sigma SA
Sigma 10mm f/2.8 EX DC Fisheye HSM10 mmf/2.8Sigma SA, Nikon F AF
Irix 11mm f/4 G11 mmf/4Nikon F AF, Canon EF
Pentax HD Pentax-DA* 11-18mm f/2.8 ED DC AW11–18 mmf/2.8Pentax KAF2
Tamron SP AF 11-18mm f/4.5-5.6 Di-II LD Aspherical (IF)11–18 mmf/11Canon EF, Nikon F AF
Venus Laowa 12mm f/2.8 Zero-D12 mmf/2.8Canon EF, Nikon F
Sigma 12-24mm f/4.5-5.6 EX DG Aspherical HSM12–24 mmf/4.5Sigma SA, Canon EF
Sigma 12-24mm F4.5-5.6 II DG HSM12–24 mmf/4.5Nikon F AF, Canon EF
Pentax smc Pentax-DA 12-24mm f/4 ED AL IF12–24 mmf/4Pentax KAF2
Samyang 14mm f/2.8 AE ED AS IF UMC14 mmf/2.8Pentax KAF, Canon EF
Sigma 14mm f/2.8 EX14 mmf/2.8Sigma SA, Canon EF
Sigma 14mm f/3.5 EX14 mmf/3.5Sigma SA, Canon EF
Sigma 14mm f/2.8 EX Aspherical HSM14 mmf/2.8Canon EF, Nikon F
Pentax smc PENTAX-DA 14mm F2.8 ED[IF]14 mmf/2.8Pentax KAF2
Irix 15mm f/2.415 mmf/2.4Canon EF, Nikon F
Sigma 15-30mm f/3.5-4.5 EX DG Aspherical15–30 mmf/3.5Sigma SA, Canon EF
Sigma 15mm f/2.8 EX DG Diagonal Fisheye15 mmf/2.8Canon EF, Sigma SA
Pentax HD Pentax-D FA 15-30mm f/2.8 ED SDM WR15–30 mmf/2.8Pentax K
Pentax smc Pentax-DA 15mm f/4 ED AL Limited15 mmf/4Pentax KAF2
Venus Laowa 15mm F/4 Wide Angle Macro15 mmf/4Nikon F AF, Canon EF
Samyang 16mm f/2.0 ED AS UMC CS16 mmf/2Nikon F AF, Canon EF
Zenitar MC 16mm f/2.816 mmf/2.8M42, Nikon F
Pentax smc Pentax-DA 16-45mm f/4 ED AL16–45 mmf/4Pentax KAF2
Pentax HD Pentax-DA 16-85mm f/3.5-5.6 ED DC WR16–85 mmf/3.5Pentax KAF2
Pentax smc Pentax-DA* 16-50mm f/2.8 ED AL IF SDM16–50 mmf/2.8Pentax KAF2
Pentax HD Pentax DA* 16-50mm f/2.8 ED PLM AW16–50 mmf/2.8Pentax KAF2
Sigma 17-50mm f/2.8 EX DC HSM17–50 mmf/2.8Pentax KAF3
Sigma 17-35mm f/2.8-4 EX DG17–35 mmf/2.8Sigma SA, Canon EF
Sigma 17-35mm F2.8-4 EX DG Aspherical HSM17–35 mmf/2.8Nikon F AF, Sigma SA
Sigma 17-70mm f/2.8-4.5 DC Macro17–70 mmf/2.8Sigma SA, Canon EF
Sigma 17-70mm f/2.8-4 DC Macro OS HSM | Contemporary 01317–70 mmf/2.8Nikon F AF, Sigma SA
Tamron SP AF 17-35mm f/2.8-4 Di LD Aspherical (IF)17–35 mmf/17Canon EF, Nikon F AF
Tamron AF 17-50mm f/2.8 XR Di-II LD (Model A16)17–50 mmf/17Canon EF, Nikon F AF

Native and adapter-free compatible lenses from the Lensfun database. Third-party and adapted lenses may also work.

How to check the Samsung GX-1S shutter count

Not every maker writes a shutter count into image files. Try `exiftool -a -G1 -s image` on an unedited original and look for a tag containing "Shutter" or "Count".

ExifTool tag: (varies). 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 Pentax KAF2 cameras

FAQ

What is the crop factor of the Samsung GX-1S?
1.53×. A 24 mm lens frames like a 37 mm lens on full frame.
What shutter speed should I use for the Milky Way with the Samsung GX-1S?
With a 8 mm lens at f/2.8, about 27 seconds keeps stars sharp (NPF rule).
How do I check the shutter count on the Samsung GX-1S?
Not every maker writes a shutter count into image files. Try `exiftool -a -G1 -s image` on an unedited original and look for a tag containing "Shutter" or "Count".
Which lenses fit the Samsung GX-1S?
Lenses for the Pentax KAF2 mount and compatible mounts (Pentax K, Pentax KA, Pentax KAF) — 190 are listed above.