Sigma 17-50mm f/2.8 EX DC OS HSM vs Tamron 18-270mm f/3.5-6.3 Di II PZD

Both are Pentax K lenses. Here is what actually differs.

Sigma

Pick the Sigma 17-50mm f/2.8 EX DC OS HSM if

You need ⅔ stop more light for low light or background blur (f/2.8 vs f/3.5)
You want a wider view: 17mm vs 18mm at the wide end

Pick the Tamron 18-270mm f/3.5-6.3 Di II PZD if

You need more reach: 270mm vs 50mm at the long end

Spec differences

15 differences

Specifications that differ between the Sigma 17-50mm f/2.8 EX DC OS HSM and the Tamron 18-270mm f/3.5-6.3 Di II PZD
	Sigma 17-50mm f/2.8 EX DC OS HSM	Tamron 18-270mm f/3.5-6.3 Di II PZD
Brand	Sigma	Tamron
Type	Zoom	Superzoom
Format	APS-C	not listed
Focal length	17-50mm	18-270mm
Max aperture	f/2.8 ⅔ stop faster	f/3.5
Weight	565 g	not listed
Length	91.8 mm	not listed
Diameter	83.5 mm	not listed
Filter thread	77 mm	not listed
Min focus distance	0.28 m	not listed
Max magnification	0.2×	not listed
Aperture blades	7	not listed
Optical design	17 elements / 13 groups	not listed
Autofocus motor	HSM	not listed
Image stabilization	Yes	not listed

1 identical spec hidden: mount. Show all

Mount: Pentax K both

Our notes

Sigma 17-50mm f/2.8 EX DC OS HSM

Sigma 17-50mm f/2.8 EX DC OS HSM: an APS-C fast standard zoom lens with a 17-50mm focal length and a maximum aperture of f/2.8, made for Pentax K mount cameras, with Optical Stabilizer and Hyper Sonic Motor autofocus. A bright standard zoom for APS-C cameras with a constant f/...

Our notes

Tamron 18-270mm f/3.5-6.3 Di II PZD

A 18-270mm f/3.5-6.3 APS-C superzoom lens, the Tamron 18-270mm f/3.5-6.3 Di II PZD is designed for Pentax K mount bodies, with quiet motor-driven autofocus. A high-ratio travel zoom covering wide-angle to telephoto in one lens.