Pentax smc Pentax-DA* 55mm f/1.4 SDM Specs & DoF

55 mm

Focal length

f/1.4

Maximum aperture

29°

Diagonal angle of view (APS-C)

APS-C

Designed for

Specifications#

Brand: Pentax
Model: smc Pentax-DA* 55mm f/1.4 SDM
Lens type: Portrait / short tele prime
Focal length: 55 mm
Maximum aperture: f/1.4
Image circle: APS-C (23.5×15.6 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 55 mm	Equiv. aperture (DoF)
APS-C	82 mm · 29°	f/2.1
APS-C (Canon)	88 mm · 27°	f/2.2
Micro Four Thirds	110 mm · 22°	f/2.8

Depth of field & background blur#

Computed on its native APS-C format (CoC 20 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: 50 mm f/1.4 on aps-c.

Focal	Aperture	at 1 m	at 2 m	at 5 m	at 10 m	Hyperfocal	Blur @2 m
55 mm	f/1.4	1.7 cm	7.0 cm	44.8 cm	1.82 m	111 m	4.7%
55 mm	f/4	4.9 cm	20.2 cm	1.30 m	5.51 m	38.7 m	1.7%
55 mm	f/8	9.8 cm	40.7 cm	2.74 m	14.0 m	19.4 m	0.8%

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 55 mm	NPF at 55 mm, f/1.4
APS-C	1/80 s	6 s	3 s
APS-C (Canon)	1/80 s	6 s	3 s
Micro Four Thirds	1/100 s	5 s	3 s

Compatible cameras#

Bodies in our database with a native Pentax K mount. Full-frame bodies switch to an APS-C crop with this lens.

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-DA 50mm f/1.8 f/1.8
Pentax HD Pentax-DA 70mm f/2.4 Limited f/2.4
Pentax smc Pentax-DA 70mm f/2.4 Limited f/2.4
Pentax smc Pentax-FA 77mm f/1.8 Limited f/1.8
Samyang 85mm f/1.4 IF UMC Aspherical f/1.4
Sigma 85mm f/1.4 EX DG HSM f/1.4
Samyang 135mm f/2 ED UMC f/2
Pentax Takumar 135mm f/2.5 Bayonet f/2.5
Pentax smc Pentax-M 135mm f/3.5 f/3.5

Frequently asked questions#

Is the Pentax smc Pentax-DA* 55mm f/1.4 SDM full frame?

No — it is designed for APS-C sensors. On a full-frame body it vignettes or triggers crop mode.

What is the Pentax smc Pentax-DA* 55mm f/1.4 SDM equivalent to on APS-C?

Its focal length is already the real value for APS-C: 55 mm frames like 84 mm on full frame.

What is the Pentax smc Pentax-DA* 55mm f/1.4 SDM good for?

As a portrait / short tele prime it suits head-and-shoulders portraits with flattering perspective and creamy backgrounds.

Sources & licences#

Lensfun lens database — CC BY-SA 3.0