Pentax smc Pentax-M Macro 1:4 100mm Specs & DoF

100 mm

Focal length

f/4

Maximum aperture

24°

Diagonal angle of view (Full frame)

Full frame

Designed for

Specifications#

Brand: Pentax
Model: smc Pentax-M Macro 1:4 100mm
Lens type: Macro
Focal length: 100 mm
Maximum aperture: f/4
Image circle: Full frame (36×24 mm)
Mount(s): Pentax K
Projection: Rectilinear
Lensfun correction profile: Yes — distortion/vignetting/TCA

Equivalent focal length on different cameras#

Field of view and depth-of-field equivalence when this lens is used on bodies with different sensor sizes (natively or via an adapter).

Camera format	At 100 mm	Equiv. aperture (DoF)
Full frame	100 mm · 24°	f/4.0
APS-C	150 mm · 16°	f/6.0
APS-C (Canon)	160 mm · 15°	f/6.4
Micro Four Thirds	200 mm · 12°	f/8.0

Depth of field & background blur#

Computed on its native Full frame format (CoC 30 µm). “Blur @2 m” is the size of an out-of-focus point at infinity, as a percentage of frame width, with the subject at 2 m — a simple bokeh index. Full table: 105 mm f/4 on full frame.

Focal	Aperture	at 1 m	at 2 m	at 5 m	at 10 m	Hyperfocal	Blur @2 m
100 mm	f/4	2.2 cm	9.1 cm	59.0 cm	2.41 m	83.4 m	3.7%
100 mm	f/8	4.3 cm	18.3 cm	1.19 m	5.04 m	41.8 m	1.8%

Handheld & night-sky limits#

NPF assumes typical 20–24 MP sensors (≈6 µm pixels on full frame, ≈3.9 µm on APS-C, ≈3.3 µm on Micro Four Thirds).

Body	Min. handheld shutter (longest focal)	500 rule at 100 mm	NPF at 100 mm, f/4
Full frame	1/100 s	5 s	3 s
APS-C	1/160 s	3 s	3 s
APS-C (Canon)	1/160 s	3 s	3 s
Micro Four Thirds	1/200 s	2 s	2 s

Compatible cameras#

Bodies in our database with a native Pentax K mount.

Adapt it to other systems#

Sony E-mount Canon RF Nikon Z Fujifilm X-mount Micro Four Thirds L-Mount Canon EF-M Fujifilm G-mount Hasselblad XCD Nikon 1 (CX)Pentax Q Samsung NX Canon EF Nikon F

Similar lenses#

Pentax smc Pentax-D FA Macro 100mm f/2.8 WR f/2.8
Sigma 90mm f/2.8 Macro AF f/2.8
Tamron SP AF 90mm f/2.8 Di Macro 172E f/2.8
Tamron SP AF 90mm f/2.8 Di Macro 1:1 f/2.8
Sigma 70-200mm f/2.8 EX DG Macro HSM II f/2.8
Sigma 70-300mm f/4-5.6 APO Macro Super II f/4–5.6
Sigma 70-300mm f/4-5.6 DG Macro f/4–5.6
Sigma 70-300mm f/4-5.6 DL Macro f/4–5.6
Sigma 70mm f/2.8 EX DG Macro f/2.8
Tamron AF 70-300mm f/4-5.6 Di LD Tele-Macro (1:2) f/4–5.6
Tamron AF 70-300mm f/4-5.6 LD Macro 1:2 f/4–5.6
Tamron SP AF 70-200mm f/2.8 Di LD (IF) Macro f/2.8

Frequently asked questions#

Is the Pentax smc Pentax-M Macro 1:4 100mm full frame?

Yes — it covers the full 36 × 24 mm frame.

What is the Pentax smc Pentax-M Macro 1:4 100mm equivalent to on APS-C?

On a 1.5× APS-C body it frames like 150 mm, and like 160 mm on Canon APS-C.

What is the Pentax smc Pentax-M Macro 1:4 100mm good for?

As a macro it suits close-ups of insects, flowers, products and details at up to life size.

Sources & licences#

Lensfun lens database — CC BY-SA 3.0