Comparison of Pentax 17-70mm ƒ/4 AL IF SDM SMC DA and Tamron 28-75mm f/2.8 Di III RXD (Model A036) [S]ave
| Attribute |  Tamron 28-75mm f/2.8 Di III RXD (Model A036) × |  Pentax 17-70mm ƒ/4 AL IF SDM SMC DA × |
|---|---|---|
| Filter Size (mm) | 67 | 67 |
| Notes | For Sony Full-frame E-mount; Dust and moisture resistant. | Included Accessories: Lens Hood |
| Closest Focus (m) | 0.19 | 0.28 |
| Magnification Ratio (x) | 0.34 | 0.31 |
| Type | Standard Zoom | Standard Zoom |
| Length (mm) | 117.8 | 93.5 |
| APS Equivalent | 42 - 112.5mm | 25.5 - 105mm |
| Zoom System | Rotary | Rotary |
| Image Circle | 35mm | APS-C |
| Focal Length (mm) | 28.00 - 75.00 | 17.00 - 70.00 |
| Brand | Tamron | Pentax |
| Name | Tamron 28-75mm f/2.8 Di III RXD (Model A036) | Pentax 17-70mm ƒ/4 AL IF SDM SMC DA |
| Weight (g) | 550 | 485 |
| Aperture (f) | 2.80 - 22.00 | 4.00 - 22.00 |
| Diaphragm Blades | 9 | 7 |
| Diagonal Angle of View (degree) | 32.20 - 75.40 | 23.00 - 79.00 |
| Lens Construction | 15 elements in 12 groups, including 1 special XLD (eXtra Low Dispersion) element, 1 LD (Low Dispersion) element, 1 GM (Glass Molded Aspherical) eleme | 17 elements in 12 groups |
| Diameter (mm) | 73 | 75 |
| Focus Details | Internal AF with RXD (Rapid eXtra-silent stepping Drive) stepper motor; DMF (Direct Manual Focus) compatible | Internal; SDM with Quick-shift Focus System |
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