Both lenses are compact, constant f/2.8 ultra-wide zooms for APS-C mirrorless cameras, so the choice comes down to focal range, mount availability and handling. The Sigma goes a little wider at the short end, while the Tamron covers a slightly different span, so choose based on how often you need the extra width. We have not used these lenses ourselves, and exact specs should be confirmed on each maker’s page.
What Each Lens Is For
The Tamron 11-20mm f/2.8 Di III-A RXD is made for APS-C mirrorless bodies and targets landscape, architecture, travel and vlogging. The Sigma 10-18mm f/2.8 DC DN Contemporary is aimed at the same crowd and belongs to Sigma’s compact Contemporary line. Both pair a bright constant aperture with a small body, which is unusual for ultra-wide zooms.
Key Differences
| Trait | Tamron 11-20mm | Sigma 10-18mm |
|---|---|---|
| Aperture | Constant f/2.8 | Constant f/2.8 |
| Wide end | 11mm | 10mm |
| Long end | 20mm | 18mm |
| Sensor format | APS-C | APS-C |
| Built-in stabilization | Check the maker’s page | Check the maker’s page |
Mount options differ between the two brands and change over time, so confirm that your camera system is supported before you compare further.
Things to Weigh
- Width: One millimeter at the wide end can matter for tight interiors and big landscapes. The Sigma has the edge on width.
- Longer end: The Tamron reaches a bit further at 20mm, which helps when you want a less stretched look for people or street scenes.
- Size and weight: Both are designed to be small. Compare the dimensions and filter thread on the maker’s pages if you carry a gimbal or small bag.
- Close focus: Wide lenses with close focusing let you create dramatic foreground effects. Check each lens for its minimum focus distance.
- Video use: Lens breathing, focus motor noise and stabilization in the camera body all matter for handheld clips.
How to Choose
- Confirm that the lens is made for your camera mount.
- Decide whether you favor the extra width of 10mm or the slightly longer 20mm end.
- Check filter size and whether you use filters for landscapes.
- Read sample images from users of your camera body to judge corner sharpness and distortion.
FAQ
Is f/2.8 important on an ultra-wide zoom?
It helps for night skies, indoor events and low light, and it gives a little more background blur up close. For daylight landscapes at f/8, the difference matters less.
Can I use either lens on a full frame camera?
Both are designed for APS-C. On a full frame body, the camera may crop the image automatically, which reduces resolution and the benefit of the wide view.
The Short Version
Choose the Sigma if the widest possible view is your priority, and choose the Tamron if you like a slightly longer top end. Both offer the same bright aperture in a small package, so mount support and handling should settle the decision.
