Which is better for travel?

The Sigma. At 290 g it is much lighter and smaller, and 18-50mm covers most travel shots. The Tamron's extra reach and stabilization help in low light but cost you weight and bag space.

Is the Tamron worth the extra $100?

If you shoot handheld video or often want more than 50mm, yes. The VC stabilization and 70mm long end are real gains. If you mostly shoot in good light and want a small kit, the Sigma saves money and weight.

Which has better image stabilization?

The Tamron, because it has built-in VC. The Sigma has no stabilization and depends on the camera body. On a body without IBIS, such as the a6100, the Tamron is the safer choice for handheld shots.

Which focuses closer?

The Sigma. It focuses down to 12.1 cm at 18mm with 1:2.8 magnification, good for close-up details. The Tamron's minimum focus distance is 0.19 m with 1:4.8 magnification.

Do both fit the same cameras?

Both come in Sony E mount for APS-C bodies. The Tamron is also sold in Fujifilm X mount; the Sigma 18-50mm f/2.8 DC DN is offered in Sony E, Fujifilm X and L mount versions.

Which is better for portraits?

The Tamron. Its 70mm long end gives a tighter framing and its 9 blades give rounder background blur. The Sigma's 50mm end is workable but shorter.

Sigma 18-50mm f/2.8 DC DN Contemporary vs Tamron 17-70mm F2.8 Di III-A VC RXD

Buy the Sigma 18-50mm f/2.8 if you want the smallest, lightest constant f/2.8 zoom for Sony APS-C and want to spend less. Buy the Tamron 17-70mm f/2.8 if you need more reach, image stabilization and a longer minimum focus distance, and can carry the extra weight. The Sigma's best new price is $499.00 at eBay as of November 6, 2026, and it dipped to $389.99 on November 4. The Tamron's best new price is $599.00 at Abt Electronics & Appliances as of November 6, 2026, about $100 more.

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