Sigma 17‑40mm F1.8 vs Tamron 17‑70mm F2.8 — Low Light vs Versatility?
Both of these lenses target serious APS-C users, but they’re built for different goals. The Sigma 17-40mm is a low-light monster with a unique constant f/1.8 aperture and internal zoom, while the Tamron 17-70mm offers more reach and stabilization for general use.
Let’s get into the key differences between these lenses.
📊 Spec Comparison Table
| Feature | Sigma 17‑40mm F1.8 | Tamron 17–70mm F2.8 VC RXD |
|---|---|---|
| Focal Length | 17–40mm | 17–70mm |
| Aperture | Constant f/1.8 | Constant f/2.8 |
| Image Stabilization | ❌ No | ✅ Yes (VC = Vibration Compensation) |
| Autofocus | HLA Linear Motor (fast/quiet) | RXD Stepping Motor (quiet, good) |
| Minimum Focus Distance | ~28 cm | 19 cm (wide) / 39 cm (tele) |
| Zoom Type | Internal (non-extending) | Extending |
| Weight | ~535g | ~525g |
| Filter Thread | 72mm | 67mm |
| Aperture Ring | ✅ Yes, clickless option | ❌ None |
| Weather Sealing | ✅ Yes | ✅ Yes |
| Price (August 2025) | $919 | $699 |
🔍 Key Differences Explained
🌙 Aperture: F1.8 vs F2.8
- Sigma’s f/1.8 is over 1 stop brighter, meaning:
- Better for night photography
- Smoother background blur
- Lower ISO in video/interviews
- Tamron’s f/2.8 is solid- but doesn’t offer the same subject separation.
📦 Range: 40mm vs 70mm
- Tamron wins on reach. At 70mm, you can shoot tighter portraits or compress backgrounds.
- Sigma stops at 40mm—it’s more of a wide-to-normal lens.
📹 Video Use
- Sigma:
- Internal zoom = better for gimbals
- De-clickable aperture ring for smooth exposure changes
- Very shallow depth of field
- Tamron:
- Built-in image stabilization (huge for handheld work)
- Lighter, smaller filter thread
- Slight focus breathing, but decent control
🏞️ Use Case Split
- Sigma: Best for creative projects, stylized portraiture, low-light shooting, narrative filmmaking.
- Tamron: Better for travel, handheld video, documentary, family shooting, or as a one-lens solution.
🏁 Verdict — Which Lens Should You Choose?
Buy the Sigma 17‑40mm F1.8 if:
✅ You shoot in low light frequently
✅ You want cinematic bokeh and subject isolation
✅ You prioritize video features like internal zoom & aperture ring
✅ You already have a telephoto lens in your kit
Buy the Tamron 17‑70mm F2.8 VC if:
✅ You want a true all-in-one walkaround lens
✅ You shoot handheld video and need stabilization
✅ You prefer longer reach for portraits or events
✅ You value travel-friendly zoom versatility
🔎 TL;DR:
- Sigma 17-40mm F1.8 = low-light beast, video-friendly, more creative control
- Tamron 17-70mm F2.8 VC = jack-of-all-trades lens with reach and stabilization
If you’re a creator who likes to shoot in controlled setups or chase cinematic looks, go Sigma. If you need one lens to do it all with minimal fuss, Tamron is the safer bet.
